bc05_23c4

Three-Point Test Cross Problem

A test cross is a way to explore the relationship between genes and their respective alleles. It is a useful tool for genetic mapping and deciphering the inheritance of traits. Specifically, a three-point test cross examines three (3) genes at the same time to learn about their assortment in gamete formation.

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is affiliated with the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene J is connected with the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.
Gene R is related to the 'rusty' phenotype. A fruit fly that is homozygous recessive for Gene R has a reddish-brown color, much like rusted iron metal.

Phenotype	Genotypes			Progeny Count
artsy, jerky, rusty	a	j	r	456
artsy, jerky	a	j	+	87
artsy, rusty	a	+	r	1,835
artsy	a	+	+	15
jerky, rusty	+	j	r	9
jerky	+	j	+	1,837
rusty	+	+	r	81
wildtype	+	+	+	480
TOTAL =				4,800

The resulting phenotypes are summarized in the table above.

The distance between genes A and R is 4 cM
The distance between genes A and J is 23 cM
The distance between genes R and J is 20 cM
The correct gene order determined from these distances is ARJ

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

In genetic studies, interference refers to the phenomenon where the occurrence of a crossover in one region of a chromosome reduces the likelihood of another crossover occurring nearby, thereby affecting the expected genetic ratios.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes A and J.

A. no interference, 0% Incorrect B. ¹/₈ = 0.1250 = 12% Incorrect C. ³/₈ = 0.3750 = 38% Correct D. ¹/₂ = 0.5000 = 50% Incorrect E. ⁵/₈ = 0.6250 = 62% Incorrect F. ⁷/₈ = 0.8750 = 88% Incorrect G. complete interference, 100% Incorrect MC

73d7_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene H is linked with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene W is analogous to the 'waxy' phenotype. A fruit fly that is homozygous recessive for Gene W has a thick protective layer that is water resistant and opague.
Gene Y is correlated with the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
horsey, waxy, yucky	h	w	y	402
horsey, waxy	h	w	+	1
horsey, yucky	h	+	y	92
horsey	h	+	+	116
waxy, yucky	+	w	y	118
waxy	+	w	+	82
yucky	+	+	y	5
wildtype	+	+	+	384
TOTAL =				1,200

The resulting phenotypes are summarized in the table above.

The distance between genes H and Y is 20 cM
The distance between genes H and W is 34 cM
The distance between genes Y and W is 15 cM
The correct gene order determined from these distances is HYW

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes H and W.

A. no interference, 0% Incorrect B. ¹/₆ = 0.1667 = 17% Incorrect C. ¹/₃ = 0.3333 = 33% Incorrect D. ¹/₂ = 0.5000 = 50% Incorrect E. ²/₃ = 0.6667 = 67% Incorrect F. ⁵/₆ = 0.8333 = 83% Correct G. complete interference, 100% Incorrect MC

af57_23c4

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is connected with the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene P is affiliated with the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.
Gene Y is correlated with the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
artsy, prickly, yucky	a	p	y	165
artsy, prickly	a	p	+	844
artsy, yucky	a	+	y	9
artsy	a	+	+	97
prickly, yucky	+	p	y	101
prickly	+	p	+	13
yucky	+	+	y	806
wildtype	+	+	+	165
TOTAL =				2,200

The resulting phenotypes are summarized in the table above.

The distance between genes P and A is 10 cM
The distance between genes P and Y is 24 cM
The distance between genes A and Y is 16 cM
The correct gene order determined from these distances is PAY

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes P and Y.

1756_38cc

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene D is correlated with the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene P is analogous to the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.
Gene Y is related to the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
dewy, prickly, yucky	d	p	y	932
dewy, prickly	d	p	+	40
dewy, yucky	d	+	y	151
dewy	d	+	+	2,740
prickly, yucky	+	p	y	2,798
prickly	+	p	+	161
yucky	+	+	y	38
wildtype	+	+	+	940
TOTAL =				7,800

The resulting phenotypes are summarized in the table above.

The distance between genes D and P is 25 cM
The distance between genes D and Y is 28 cM
The distance between genes P and Y is 5 cM
The correct gene order determined from these distances is DPY

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes D and Y.

A. no interference, 0% Incorrect B. ¹/₅ = 0.2000 = 20% Correct C. ²/₅ = 0.4000 = 40% Incorrect D. ¹/₂ = 0.5000 = 50% Incorrect E. ³/₅ = 0.6000 = 60% Incorrect F. ⁴/₅ = 0.8000 = 80% Incorrect G. complete interference, 100% Incorrect MC

6f2d_38cc

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene D is linked with the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene F is linked with the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.
Gene X is connected with the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.

Phenotype	Genotypes			Progeny Count
dewy, fuzzy, xanthic	d	f	x	365
dewy, fuzzy	d	f	+	2,560
dewy, xanthic	d	+	x	41
dewy	d	+	+	915
fuzzy, xanthic	+	f	x	933
fuzzy	+	f	+	36
xanthic	+	+	x	2,522
wildtype	+	+	+	328
TOTAL =				7,700

The resulting phenotypes are summarized in the table above.

The distance between genes F and D is 25 cM
The distance between genes F and X is 33 cM
The distance between genes D and X is 10 cM
The correct gene order determined from these distances is FDX

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes F and X.

A. no interference, 0% Incorrect B. ¹/₅ = 0.2000 = 20% Incorrect C. ²/₅ = 0.4000 = 40% Incorrect D. ¹/₂ = 0.5000 = 50% Incorrect E. ³/₅ = 0.6000 = 60% Correct F. ⁴/₅ = 0.8000 = 80% Incorrect G. complete interference, 100% Incorrect MC

2809_2477

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is affiliated with the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene J is connected with the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.
Gene X is correlated with the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.

Phenotype	Genotypes			Progeny Count
artsy, jerky, xanthic	a	j	x	2,251
artsy, jerky	a	j	+	1,029
artsy, xanthic	a	+	x	48
artsy	a	+	+	342
jerky, xanthic	+	j	x	361
jerky	+	j	+	63
xanthic	+	+	x	1,080
wildtype	+	+	+	2,226
TOTAL =				7,400

The resulting phenotypes are summarized in the table above.

The distance between genes A and J is 11 cM
The distance between genes A and X is 38 cM
The distance between genes J and X is 30 cM
The correct gene order determined from these distances is AJX

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes A and X.

A. no interference, 0% Incorrect B. ¹/₁₁ = 0.0909 = 9% Incorrect C. ³/₁₁ = 0.2727 = 27% Incorrect D. ⁵/₁₁ = 0.4545 = 45% Incorrect E. ¹/₂ = 0.5000 = 50% Incorrect F. ⁶/₁₁ = 0.5455 = 55% Correct G. ⁷/₁₁ = 0.6364 = 64% Incorrect H. ⁹/₁₁ = 0.8182 = 82% Incorrect I. complete interference, 100% Incorrect MC

e856_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene C is affiliated with the 'chummy' phenotype. A fruit fly that is homozygous recessive for Gene C shows behavior where it always maintains a close distance to other flies.
Gene P is correlated with the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.
Gene X is linked with the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.

Phenotype	Genotypes			Progeny Count
chummy, prickly, xanthic	c	p	x	167
chummy, prickly	c	p	+	627
chummy, xanthic	c	+	x	2,410
chummy	c	+	+	785
prickly, xanthic	+	p	x	790
prickly	+	p	+	2,315
xanthic	+	+	x	633
wildtype	+	+	+	148
TOTAL =				7,875

The resulting phenotypes are summarized in the table above.

The distance between genes C and P is 20 cM
The distance between genes C and X is 36 cM
The distance between genes P and X is 24 cM
The correct gene order determined from these distances is CPX

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes C and X.

A. no interference, 0% Incorrect B. ¹/₆ = 0.1667 = 17% Correct C. ¹/₃ = 0.3333 = 33% Incorrect D. ¹/₂ = 0.5000 = 50% Incorrect E. ²/₃ = 0.6667 = 67% Incorrect F. ⁵/₆ = 0.8333 = 83% Incorrect G. complete interference, 100% Incorrect MC

e31d_10af

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is connected with the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene E is linked with the 'eery' phenotype. A fruit fly that is homozygous recessive for Gene E appears to have something off, crooked limbs and other twisted appendages.
Gene H is affiliated with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.

Phenotype	Genotypes			Progeny Count
artsy, eery, horsey	a	e	h	83
artsy, eery	a	e	+	776
artsy, horsey	a	+	h	13
artsy	a	+	+	138
eery, horsey	+	e	h	122
eery	+	e	+	7
horsey	+	+	h	764
wildtype	+	+	+	97
TOTAL =				2,000

The resulting phenotypes are summarized in the table above.

The distance between genes E and A is 14 cM
The distance between genes E and H is 22 cM
The distance between genes A and H is 10 cM
The correct gene order determined from these distances is EAH

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes E and H.

A. no interference, 0% Incorrect B. ¹/₇ = 0.1429 = 14% Incorrect C. ²/₇ = 0.2857 = 29% Correct D. ³/₇ = 0.4286 = 43% Incorrect E. ¹/₂ = 0.5000 = 50% Incorrect F. ⁴/₇ = 0.5714 = 57% Incorrect G. ⁵/₇ = 0.7143 = 71% Incorrect H. ⁶/₇ = 0.8571 = 86% Incorrect I. complete interference, 100% Incorrect MC

f33e_f4f2

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene D is analogous to the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene H is connected with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene X is correlated with the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.

Phenotype	Genotypes			Progeny Count
dewy, horsey, xanthic	d	h	x	134
dewy, horsey	d	h	+	1,948
dewy, xanthic	d	+	x	630
dewy	d	+	+	731
horsey, xanthic	+	h	x	739
horsey	+	h	+	630
xanthic	+	+	x	2,042
wildtype	+	+	+	146
TOTAL =				7,000

The resulting phenotypes are summarized in the table above.

The distance between genes D and X is 22 cM
The distance between genes D and H is 39 cM
The distance between genes X and H is 25 cM
The correct gene order determined from these distances is DXH

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes D and H.

A. no interference, 0% Incorrect B. ¹/₁₁ = 0.0909 = 9% Incorrect C. ³/₁₁ = 0.2727 = 27% Correct D. ⁵/₁₁ = 0.4545 = 45% Incorrect E. ¹/₂ = 0.5000 = 50% Incorrect F. ⁷/₁₁ = 0.6364 = 64% Incorrect G. ⁸/₁₁ = 0.7273 = 73% Incorrect H. ⁹/₁₁ = 0.8182 = 82% Incorrect I. complete interference, 100% Incorrect MC

fdaa_596f

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene F is related to the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.
Gene M is associated with the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.
Gene Y is related to the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
fuzzy, mushy, yucky	f	m	y	477
fuzzy, mushy	f	m	+	3
fuzzy, yucky	f	+	y	93
fuzzy	f	+	+	28
mushy, yucky	+	m	y	26
mushy	+	m	+	81
yucky	+	+	y	3
wildtype	+	+	+	489
TOTAL =				1,200

The resulting phenotypes are summarized in the table above.

The distance between genes F and Y is 5 cM
The distance between genes F and M is 19 cM
The distance between genes Y and M is 15 cM
The correct gene order determined from these distances is FYM

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes F and M.

A. no interference, 0% Incorrect B. ¹/₃ = 0.3333 = 33% Correct C. ¹/₂ = 0.5000 = 50% Incorrect D. ²/₃ = 0.6667 = 67% Incorrect E. complete interference, 100% Incorrect MC

d2da_9c3b

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene F is related to the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.
Gene H is correlated with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene J is correlated with the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.

Phenotype	Genotypes			Progeny Count
fuzzy, horsey, jerky	f	h	j	165
fuzzy, horsey	f	h	+	1,072
fuzzy, jerky	f	+	j	2,446
fuzzy	f	+	+	469
horsey, jerky	+	h	j	444
horsey	+	h	+	2,451
jerky	+	+	j	1,086
wildtype	+	+	+	167
TOTAL =				8,300

The resulting phenotypes are summarized in the table above.

The distance between genes F and H is 30 cM
The distance between genes F and J is 37 cM
The distance between genes H and J is 15 cM
The correct gene order determined from these distances is FHJ

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes F and J.

A. no interference, 0% Incorrect B. ¹/₉ = 0.1111 = 11% Correct C. ¹/₃ = 0.3333 = 33% Incorrect D. ¹/₂ = 0.5000 = 50% Incorrect E. ⁵/₉ = 0.5556 = 56% Incorrect F. ⁷/₉ = 0.7778 = 78% Incorrect G. ⁸/₉ = 0.8889 = 89% Incorrect H. complete interference, 100% Incorrect MC

17b1_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene N is affiliated with the 'nerdy' phenotype. A fruit fly that is homozygous recessive for Gene N has large, prominent eyes that stand out, much like thick-rimmed glasses.
Gene P is correlated with the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.
Gene Y is affiliated with the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
nerdy, prickly, yucky	n	p	y	11
nerdy, prickly	n	p	+	89
nerdy, yucky	n	+	y	259
nerdy	n	+	+	1,877
prickly, yucky	+	p	y	1,964
prickly	+	p	+	270
yucky	+	+	y	118
wildtype	+	+	+	12
TOTAL =				4,600

The resulting phenotypes are summarized in the table above.

The distance between genes P and N is 5 cM
The distance between genes P and Y is 16 cM
The distance between genes N and Y is 12 cM
The correct gene order determined from these distances is PNY

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes P and Y.

2af5_596f

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene B is connected with the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene R is related to the 'rusty' phenotype. A fruit fly that is homozygous recessive for Gene R has a reddish-brown color, much like rusted iron metal.
Gene Y is correlated with the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
bumpy, rusty, yucky	b	r	y	36
bumpy, rusty	b	r	+	3,105
bumpy, yucky	b	+	y	575
bumpy	b	+	+	387
rusty, yucky	+	r	y	351
rusty	+	r	+	573
yucky	+	+	y	3,127
wildtype	+	+	+	46
TOTAL =				8,200

The resulting phenotypes are summarized in the table above.

The distance between genes B and Y is 15 cM
The distance between genes B and R is 23 cM
The distance between genes Y and R is 10 cM
The correct gene order determined from these distances is BYR

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes B and R.

A. no interference, 0% Incorrect B. ¹/₃ = 0.3333 = 33% Correct C. ¹/₂ = 0.5000 = 50% Incorrect D. ²/₃ = 0.6667 = 67% Incorrect E. complete interference, 100% Incorrect MC

ee9f_40f0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene B is associated with the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene D is related to the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene N is associated with the 'nerdy' phenotype. A fruit fly that is homozygous recessive for Gene N has large, prominent eyes that stand out, much like thick-rimmed glasses.

Phenotype	Genotypes			Progeny Count
bumpy, dewy, nerdy	b	d	n	756
bumpy, dewy	b	d	+	86
bumpy, nerdy	b	+	n	358
bumpy	b	+	+	210
dewy, nerdy	+	d	n	196
dewy	+	d	+	328
nerdy	+	+	n	68
wildtype	+	+	+	798
TOTAL =				2,800

The resulting phenotypes are summarized in the table above.

The distance between genes B and N is 20 cM
The distance between genes B and D is 39 cM
The distance between genes N and D is 30 cM
The correct gene order determined from these distances is BND

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes B and D.

A. no interference, 0% Incorrect B. ¹/₁₂ = 0.0833 = 8% Correct C. ¹/₄ = 0.2500 = 25% Incorrect D. ⁵/₁₂ = 0.4167 = 42% Incorrect E. ¹/₂ = 0.5000 = 50% Incorrect F. ⁷/₁₂ = 0.5833 = 58% Incorrect G. ³/₄ = 0.7500 = 75% Incorrect H. ¹¹/₁₂ = 0.9167 = 92% Incorrect I. complete interference, 100% Incorrect MC

763d_596f

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene B is analogous to the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene F is correlated with the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.
Gene H is connected with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.

Phenotype	Genotypes			Progeny Count
bumpy, fuzzy, horsey	b	f	h	1,131
bumpy, fuzzy	b	f	+	158
bumpy, horsey	b	+	h	15
bumpy	b	+	+	557
fuzzy, horsey	+	f	h	516
fuzzy	+	f	+	22
horsey	+	+	h	175
wildtype	+	+	+	1,126
TOTAL =				3,700

The resulting phenotypes are summarized in the table above.

The distance between genes B and F is 30 cM
The distance between genes B and H is 38 cM
The distance between genes F and H is 10 cM
The correct gene order determined from these distances is BFH

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes B and H.

A. no interference, 0% Incorrect B. ¹/₃ = 0.3333 = 33% Incorrect C. ¹/₂ = 0.5000 = 50% Incorrect D. ²/₃ = 0.6667 = 67% Correct E. complete interference, 100% Incorrect MC

f598_38cc

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene D is related to the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene M is connected with the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.
Gene W is affiliated with the 'waxy' phenotype. A fruit fly that is homozygous recessive for Gene W has a thick protective layer that is water resistant and opague.

Phenotype	Genotypes			Progeny Count
dewy, mushy, waxy	d	m	w	1,726
dewy, mushy	d	m	+	555
dewy, waxy	d	+	w	29
dewy	d	+	+	94
mushy, waxy	+	m	w	98
mushy	+	m	+	19
waxy	+	+	w	597
wildtype	+	+	+	1,682
TOTAL =				4,800

The resulting phenotypes are summarized in the table above.

The distance between genes D and M is 5 cM
The distance between genes D and W is 28 cM
The distance between genes M and W is 25 cM
The correct gene order determined from these distances is DMW

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes D and W.

f996_596f

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene D is affiliated with the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene J is correlated with the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.
Gene P is affiliated with the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.

Phenotype	Genotypes			Progeny Count
dewy, jerky, prickly	d	j	p	169
dewy, jerky	d	j	+	2,593
dewy, prickly	d	+	p	892
dewy	d	+	+	40
jerky, prickly	+	j	p	34
jerky	+	j	+	884
prickly	+	+	p	2,587
wildtype	+	+	+	201
TOTAL =				7,400

The resulting phenotypes are summarized in the table above.

The distance between genes D and J is 25 cM
The distance between genes D and P is 29 cM
The distance between genes J and P is 6 cM
The correct gene order determined from these distances is DJP

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes D and P.

A. no interference, 0% Incorrect B. ¹/₃ = 0.3333 = 33% Correct C. ¹/₂ = 0.5000 = 50% Incorrect D. ²/₃ = 0.6667 = 67% Incorrect E. complete interference, 100% Incorrect MC

8e0d_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is correlated with the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene B is analogous to the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene J is analogous to the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.

Phenotype	Genotypes			Progeny Count
artsy, bumpy, jerky	a	b	j	396
artsy, bumpy	a	b	+	2,757
artsy, jerky	a	+	j	489
artsy	a	+	+	51
bumpy, jerky	+	b	j	60
bumpy	+	b	+	510
jerky	+	+	j	2,756
wildtype	+	+	+	381
TOTAL =				7,400

The resulting phenotypes are summarized in the table above.

The distance between genes A and B is 15 cM
The distance between genes A and J is 24 cM
The distance between genes B and J is 12 cM
The correct gene order determined from these distances is ABJ

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes A and J.

9be1_10af

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene D is associated with the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene T is related to the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.
Gene W is connected with the 'waxy' phenotype. A fruit fly that is homozygous recessive for Gene W has a thick protective layer that is water resistant and opague.

Phenotype	Genotypes			Progeny Count
dewy, tipsy, waxy	d	t	w	82
dewy, tipsy	d	t	+	2,375
dewy, waxy	d	+	w	1,314
dewy	d	+	+	251
tipsy, waxy	+	t	w	235
tipsy	+	t	+	1,359
waxy	+	+	w	2,404
wildtype	+	+	+	80
TOTAL =				8,100

The resulting phenotypes are summarized in the table above.

The distance between genes D and W is 35 cM
The distance between genes D and T is 39 cM
The distance between genes W and T is 8 cM
The correct gene order determined from these distances is DWT

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes D and T.

f832_23c4

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene C is analogous to the 'chummy' phenotype. A fruit fly that is homozygous recessive for Gene C shows behavior where it always maintains a close distance to other flies.
Gene D is linked with the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene M is affiliated with the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.

Phenotype	Genotypes			Progeny Count
chummy, dewy, mushy	c	d	m	2,584
chummy, dewy	c	d	+	886
chummy, mushy	c	+	m	520
chummy	c	+	+	160
dewy, mushy	+	d	m	127
dewy	+	d	+	505
mushy	+	+	m	877
wildtype	+	+	+	2,541
TOTAL =				8,200

The resulting phenotypes are summarized in the table above.

The distance between genes D and C is 16 cM
The distance between genes D and M is 34 cM
The distance between genes C and M is 25 cM
The correct gene order determined from these distances is DCM

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes D and M.

A. no interference, 0% Incorrect B. ¹/₈ = 0.1250 = 12% Correct C. ³/₈ = 0.3750 = 38% Incorrect D. ¹/₂ = 0.5000 = 50% Incorrect E. ⁵/₈ = 0.6250 = 62% Incorrect F. ⁷/₈ = 0.8750 = 88% Incorrect G. complete interference, 100% Incorrect MC

90cc_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is linked with the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene B is analogous to the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene F is related to the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.

Phenotype	Genotypes			Progeny Count
artsy, bumpy, fuzzy	a	b	f	598
artsy, bumpy	a	b	+	207
artsy, fuzzy	a	+	f	10
artsy	a	+	+	1,231
bumpy, fuzzy	+	b	f	1,189
bumpy	+	b	+	10
fuzzy	+	+	f	173
wildtype	+	+	+	582
TOTAL =				4,000

The resulting phenotypes are summarized in the table above.

The distance between genes A and F is 30 cM
The distance between genes A and B is 39 cM
The distance between genes F and B is 10 cM
The correct gene order determined from these distances is AFB

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes A and B.

b3e5_23c4

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene F is affiliated with the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.
Gene J is connected with the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.
Gene N is linked with the 'nerdy' phenotype. A fruit fly that is homozygous recessive for Gene N has large, prominent eyes that stand out, much like thick-rimmed glasses.

Phenotype	Genotypes			Progeny Count
fuzzy, jerky, nerdy	f	j	n	925
fuzzy, jerky	f	j	+	2,546
fuzzy, nerdy	f	+	n	109
fuzzy	f	+	+	577
jerky, nerdy	+	j	n	557
jerky	+	j	+	101
nerdy	+	+	n	2,620
wildtype	+	+	+	965
TOTAL =				8,400

The resulting phenotypes are summarized in the table above.

The distance between genes J and F is 16 cM
The distance between genes J and N is 36 cM
The distance between genes F and N is 25 cM
The correct gene order determined from these distances is JFN

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes J and N.

6069_596f

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene K is related to the 'kidney' phenotype. A fruit fly that is homozygous recessive for Gene K has a body shape that is curved, similar to a kidney bean.
Gene P is associated with the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.
Gene W is associated with the 'waxy' phenotype. A fruit fly that is homozygous recessive for Gene W has a thick protective layer that is water resistant and opague.

Phenotype	Genotypes			Progeny Count
kidney, prickly, waxy	k	p	w	1,971
kidney, prickly	k	p	+	874
kidney, waxy	k	+	w	398
kidney	k	+	+	106
prickly, waxy	+	p	w	98
prickly	+	p	+	418
waxy	+	+	w	962
wildtype	+	+	+	1,973
TOTAL =				6,800

The resulting phenotypes are summarized in the table above.

The distance between genes P and K is 15 cM
The distance between genes P and W is 39 cM
The distance between genes K and W is 30 cM
The correct gene order determined from these distances is PKW

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes P and W.

A. no interference, 0% Incorrect B. ¹/₃ = 0.3333 = 33% Correct C. ¹/₂ = 0.5000 = 50% Incorrect D. ²/₃ = 0.6667 = 67% Incorrect E. complete interference, 100% Incorrect MC

c933_38cc

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene E is related to the 'eery' phenotype. A fruit fly that is homozygous recessive for Gene E appears to have something off, crooked limbs and other twisted appendages.
Gene H is associated with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene T is linked with the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.

Phenotype	Genotypes			Progeny Count
eery, horsey, tipsy	e	h	t	82
eery, horsey	e	h	+	371
eery, tipsy	e	+	t	1,989
eery	e	+	+	659
horsey, tipsy	+	h	t	705
horsey	+	h	+	1,917
tipsy	+	+	t	373
wildtype	+	+	+	104
TOTAL =				6,200

The resulting phenotypes are summarized in the table above.

The distance between genes E and H is 15 cM
The distance between genes E and T is 34 cM
The distance between genes H and T is 25 cM
The correct gene order determined from these distances is EHT

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes E and T.

c519_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene J is connected with the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.
Gene K is connected with the 'kidney' phenotype. A fruit fly that is homozygous recessive for Gene K has a body shape that is curved, similar to a kidney bean.
Gene R is affiliated with the 'rusty' phenotype. A fruit fly that is homozygous recessive for Gene R has a reddish-brown color, much like rusted iron metal.

Phenotype	Genotypes			Progeny Count
jerky, kidney, rusty	j	k	r	22
jerky, kidney	j	k	+	103
jerky, rusty	j	+	r	150
jerky	j	+	+	585
kidney, rusty	+	k	r	576
kidney	+	k	+	151
rusty	+	+	r	112
wildtype	+	+	+	21
TOTAL =				1,720

The resulting phenotypes are summarized in the table above.

The distance between genes K and J is 15 cM
The distance between genes K and R is 30 cM
The distance between genes J and R is 20 cM
The correct gene order determined from these distances is KJR

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes K and R.

63e0_c58a

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene C is related to the 'chummy' phenotype. A fruit fly that is homozygous recessive for Gene C shows behavior where it always maintains a close distance to other flies.
Gene P is associated with the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.
Gene W is connected with the 'waxy' phenotype. A fruit fly that is homozygous recessive for Gene W has a thick protective layer that is water resistant and opague.

Phenotype	Genotypes			Progeny Count
chummy, prickly, waxy	c	p	w	810
chummy, prickly	c	p	+	2,925
chummy, waxy	c	+	w	86
chummy	c	+	+	734
prickly, waxy	+	p	w	738
prickly	+	p	+	98
waxy	+	+	w	2,963
wildtype	+	+	+	846
TOTAL =				9,200

The resulting phenotypes are summarized in the table above.

The distance between genes P and C is 18 cM
The distance between genes P and W is 34 cM
The distance between genes C and W is 20 cM
The correct gene order determined from these distances is PCW

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes P and W.

A. no interference, 0% Incorrect B. ¹/₉ = 0.1111 = 11% Incorrect C. ¹/₃ = 0.3333 = 33% Incorrect D. ⁴/₉ = 0.4444 = 44% Correct E. ¹/₂ = 0.5000 = 50% Incorrect F. ⁵/₉ = 0.5556 = 56% Incorrect G. ⁷/₉ = 0.7778 = 78% Incorrect H. complete interference, 100% Incorrect MC

7e49_10af

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene B is affiliated with the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene M is related to the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.
Gene T is related to the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.

Phenotype	Genotypes			Progeny Count
bumpy, mushy, tipsy	b	m	t	655
bumpy, mushy	b	m	+	791
bumpy, tipsy	b	+	t	169
bumpy	b	+	+	2,304
mushy, tipsy	+	m	t	2,376
mushy	+	m	+	191
tipsy	+	+	t	849
wildtype	+	+	+	665
TOTAL =				8,000

The resulting phenotypes are summarized in the table above.

The distance between genes B and T is 21 cM
The distance between genes B and M is 37 cM
The distance between genes T and M is 25 cM
The correct gene order determined from these distances is BTM

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes B and M.

A. no interference, 0% Incorrect B. ¹/₇ = 0.1429 = 14% Correct C. ²/₇ = 0.2857 = 29% Incorrect D. ³/₇ = 0.4286 = 43% Incorrect E. ¹/₂ = 0.5000 = 50% Incorrect F. ⁴/₇ = 0.5714 = 57% Incorrect G. ⁵/₇ = 0.7143 = 71% Incorrect H. ⁶/₇ = 0.8571 = 86% Incorrect I. complete interference, 100% Incorrect MC

9ae6_38cc

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene E is associated with the 'eery' phenotype. A fruit fly that is homozygous recessive for Gene E appears to have something off, crooked limbs and other twisted appendages.
Gene M is correlated with the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.
Gene P is correlated with the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.

Phenotype	Genotypes			Progeny Count
eery, mushy, prickly	e	m	p	750
eery, mushy	e	m	+	232
eery, prickly	e	+	p	2,206
eery	e	+	+	65
mushy, prickly	+	m	p	65
mushy	+	m	+	2,149
prickly	+	+	p	288
wildtype	+	+	+	745
TOTAL =				6,500

The resulting phenotypes are summarized in the table above.

The distance between genes E and P is 10 cM
The distance between genes E and M is 31 cM
The distance between genes P and M is 25 cM
The correct gene order determined from these distances is EPM

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes E and M.

a0aa_10af

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene F is connected with the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.
Gene H is connected with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene J is analogous to the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.

Phenotype	Genotypes			Progeny Count
fuzzy, horsey, jerky	f	h	j	1,967
fuzzy, horsey	f	h	+	32
fuzzy, jerky	f	+	j	1,124
fuzzy	f	+	+	97
horsey, jerky	+	h	j	92
horsey	+	h	+	1,018
jerky	+	+	j	31
wildtype	+	+	+	1,939
TOTAL =				6,300

The resulting phenotypes are summarized in the table above.

The distance between genes F and J is 4 cM
The distance between genes F and H is 37 cM
The distance between genes J and H is 35 cM
The correct gene order determined from these distances is FJH

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes F and H.

92f5_40f0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene C is analogous to the 'chummy' phenotype. A fruit fly that is homozygous recessive for Gene C shows behavior where it always maintains a close distance to other flies.
Gene W is analogous to the 'waxy' phenotype. A fruit fly that is homozygous recessive for Gene W has a thick protective layer that is water resistant and opague.
Gene X is correlated with the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.

Phenotype	Genotypes			Progeny Count
chummy, waxy, xanthic	c	w	x	1,004
chummy, waxy	c	w	+	309
chummy, xanthic	c	+	x	249
chummy	c	+	+	21
waxy, xanthic	+	w	x	27
waxy	+	w	+	279
xanthic	+	+	x	283
wildtype	+	+	+	1,028
TOTAL =				3,200

The resulting phenotypes are summarized in the table above.

The distance between genes W and C is 18 cM
The distance between genes W and X is 35 cM
The distance between genes C and X is 20 cM
The correct gene order determined from these distances is WCX

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes W and X.

A. no interference, 0% Incorrect B. ¹/₁₂ = 0.0833 = 8% Incorrect C. ¹/₄ = 0.2500 = 25% Incorrect D. ⁵/₁₂ = 0.4167 = 42% Incorrect E. ¹/₂ = 0.5000 = 50% Incorrect F. ⁷/₁₂ = 0.5833 = 58% Correct G. ³/₄ = 0.7500 = 75% Incorrect H. ¹¹/₁₂ = 0.9167 = 92% Incorrect I. complete interference, 100% Incorrect MC

e8a1_9c3b

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is related to the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene M is correlated with the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.
Gene N is associated with the 'nerdy' phenotype. A fruit fly that is homozygous recessive for Gene N has large, prominent eyes that stand out, much like thick-rimmed glasses.

Phenotype	Genotypes			Progeny Count
artsy, mushy, nerdy	a	m	n	504
artsy, mushy	a	m	+	219
artsy, nerdy	a	+	n	63
artsy	a	+	+	1,040
mushy, nerdy	+	m	n	1,143
mushy	+	m	+	85
nerdy	+	+	n	188
wildtype	+	+	+	458
TOTAL =				3,700

The resulting phenotypes are summarized in the table above.

The distance between genes A and N is 30 cM
The distance between genes A and M is 37 cM
The distance between genes N and M is 15 cM
The correct gene order determined from these distances is ANM

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes A and M.

c794_c58a

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene H is connected with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene P is connected with the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.
Gene R is affiliated with the 'rusty' phenotype. A fruit fly that is homozygous recessive for Gene R has a reddish-brown color, much like rusted iron metal.

Phenotype	Genotypes			Progeny Count
horsey, prickly, rusty	h	p	r	11
horsey, prickly	h	p	+	647
horsey, rusty	h	+	r	53
horsey	h	+	+	1,479
prickly, rusty	+	p	r	1,491
prickly	+	p	+	57
rusty	+	+	r	651
wildtype	+	+	+	11
TOTAL =				4,400

The resulting phenotypes are summarized in the table above.

The distance between genes P and H is 30 cM
The distance between genes P and R is 32 cM
The distance between genes H and R is 3 cM
The correct gene order determined from these distances is PHR

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes P and R.

f907_e662

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene B is related to the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene H is correlated with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene K is correlated with the 'kidney' phenotype. A fruit fly that is homozygous recessive for Gene K has a body shape that is curved, similar to a kidney bean.

Phenotype	Genotypes			Progeny Count
bumpy, horsey, kidney	b	h	k	66
bumpy, horsey	b	h	+	1,335
bumpy, kidney	b	+	k	698
bumpy	b	+	+	32
horsey, kidney	+	h	k	31
horsey	+	h	+	625
kidney	+	+	k	1,332
wildtype	+	+	+	81
TOTAL =				4,200

The resulting phenotypes are summarized in the table above.

The distance between genes B and H is 33 cM
The distance between genes B and K is 35 cM
The distance between genes H and K is 5 cM
The correct gene order determined from these distances is BHK

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes B and K.

A. no interference, 0% Incorrect B. ¹/₁₁ = 0.0909 = 9% Correct C. ³/₁₁ = 0.2727 = 27% Incorrect D. ⁵/₁₁ = 0.4545 = 45% Incorrect E. ¹/₂ = 0.5000 = 50% Incorrect F. ⁷/₁₁ = 0.6364 = 64% Incorrect G. ⁹/₁₁ = 0.8182 = 82% Incorrect H. ¹⁰/₁₁ = 0.9091 = 91% Incorrect I. complete interference, 100% Incorrect MC

5cc9_c58a

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene P is analogous to the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.
Gene T is linked with the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.
Gene W is analogous to the 'waxy' phenotype. A fruit fly that is homozygous recessive for Gene W has a thick protective layer that is water resistant and opague.

Phenotype	Genotypes			Progeny Count
prickly, tipsy, waxy	p	t	w	42
prickly, tipsy	p	t	+	1,148
prickly, waxy	p	+	w	3,186
prickly	p	+	+	392
tipsy, waxy	+	t	w	368
tipsy	+	t	+	3,179
waxy	+	+	w	1,132
wildtype	+	+	+	53
TOTAL =				9,500

The resulting phenotypes are summarized in the table above.

The distance between genes P and T is 25 cM
The distance between genes P and W is 32 cM
The distance between genes T and W is 9 cM
The correct gene order determined from these distances is PTW

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes P and W.

A. no interference, 0% Incorrect B. ¹/₉ = 0.1111 = 11% Incorrect C. ¹/₃ = 0.3333 = 33% Incorrect D. ⁴/₉ = 0.4444 = 44% Incorrect E. ¹/₂ = 0.5000 = 50% Incorrect F. ⁵/₉ = 0.5556 = 56% Correct G. ⁷/₉ = 0.7778 = 78% Incorrect H. complete interference, 100% Incorrect MC

6e52_38cc

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene B is associated with the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene D is analogous to the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene K is connected with the 'kidney' phenotype. A fruit fly that is homozygous recessive for Gene K has a body shape that is curved, similar to a kidney bean.

Phenotype	Genotypes			Progeny Count
bumpy, dewy, kidney	b	d	k	749
bumpy, dewy	b	d	+	2,073
bumpy, kidney	b	+	k	267
bumpy	b	+	+	47
dewy, kidney	+	d	k	49
dewy	+	d	+	277
kidney	+	+	k	2,183
wildtype	+	+	+	755
TOTAL =				6,400

The resulting phenotypes are summarized in the table above.

The distance between genes B and D is 10 cM
The distance between genes B and K is 32 cM
The distance between genes D and K is 25 cM
The correct gene order determined from these distances is BDK

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes B and K.

A. no interference, 0% Incorrect B. ¹/₅ = 0.2000 = 20% Incorrect C. ²/₅ = 0.4000 = 40% Correct D. ¹/₂ = 0.5000 = 50% Incorrect E. ³/₅ = 0.6000 = 60% Incorrect F. ⁴/₅ = 0.8000 = 80% Incorrect G. complete interference, 100% Incorrect MC

b6c3_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene H is linked with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene K is connected with the 'kidney' phenotype. A fruit fly that is homozygous recessive for Gene K has a body shape that is curved, similar to a kidney bean.
Gene T is correlated with the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.

Phenotype	Genotypes			Progeny Count
horsey, kidney, tipsy	h	k	t	66
horsey, kidney	h	k	+	383
horsey, tipsy	h	+	t	2,591
horsey	h	+	+	637
kidney, tipsy	+	k	t	677
kidney	+	k	+	2,519
tipsy	+	+	t	347
wildtype	+	+	+	80
TOTAL =				7,300

The resulting phenotypes are summarized in the table above.

The distance between genes H and K is 12 cM
The distance between genes H and T is 28 cM
The distance between genes K and T is 20 cM
The correct gene order determined from these distances is HKT

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes H and T.

a19f_9bcc

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is connected with the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene F is correlated with the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.
Gene Y is correlated with the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
artsy, fuzzy, yucky	a	f	y	335
artsy, fuzzy	a	f	+	20
artsy, yucky	a	+	y	720
artsy	a	+	+	2,514
fuzzy, yucky	+	f	y	2,562
fuzzy	+	f	+	684
yucky	+	+	y	16
wildtype	+	+	+	349
TOTAL =				7,200

The resulting phenotypes are summarized in the table above.

The distance between genes A and F is 10 cM
The distance between genes A and Y is 29 cM
The distance between genes F and Y is 20 cM
The correct gene order determined from these distances is AFY

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes A and Y.

A. no interference, 0% Incorrect B. ¹/₄ = 0.2500 = 25% Incorrect C. ¹/₂ = 0.5000 = 50% Incorrect D. ³/₄ = 0.7500 = 75% Correct E. complete interference, 100% Incorrect MC

8875_c58a

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene H is connected with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene P is linked with the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.
Gene T is associated with the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.

Phenotype	Genotypes			Progeny Count
horsey, prickly, tipsy	h	p	t	2,138
horsey, prickly	h	p	+	568
horsey, tipsy	h	+	t	30
horsey	h	+	+	240
prickly, tipsy	+	p	t	248
prickly	+	p	+	31
tipsy	+	+	t	591
wildtype	+	+	+	2,254
TOTAL =				6,100

The resulting phenotypes are summarized in the table above.

The distance between genes H and P is 9 cM
The distance between genes H and T is 27 cM
The distance between genes P and T is 20 cM
The correct gene order determined from these distances is HPT

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes H and T.

e1ba_2477

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene M is affiliated with the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.
Gene P is linked with the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.
Gene Y is affiliated with the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
mushy, prickly, yucky	m	p	y	53
mushy, prickly	m	p	+	2,050
mushy, yucky	m	+	y	970
mushy	m	+	+	309
prickly, yucky	+	p	y	337
prickly	+	p	+	968
yucky	+	+	y	2,064
wildtype	+	+	+	49
TOTAL =				6,800

The resulting phenotypes are summarized in the table above.

The distance between genes M and Y is 30 cM
The distance between genes M and P is 38 cM
The distance between genes Y and P is 11 cM
The correct gene order determined from these distances is MYP

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes M and P.

b143_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene J is correlated with the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.
Gene M is linked with the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.
Gene Y is associated with the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
jerky, mushy, yucky	j	m	y	819
jerky, mushy	j	m	+	37
jerky, yucky	j	+	y	323
jerky	j	+	+	12
mushy, yucky	+	m	y	12
mushy	+	m	+	373
yucky	+	+	y	35
wildtype	+	+	+	789
TOTAL =				2,400

The resulting phenotypes are summarized in the table above.

The distance between genes M and J is 30 cM
The distance between genes M and Y is 32 cM
The distance between genes J and Y is 4 cM
The correct gene order determined from these distances is MJY

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes M and Y.

34b2_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene N is related to the 'nerdy' phenotype. A fruit fly that is homozygous recessive for Gene N has large, prominent eyes that stand out, much like thick-rimmed glasses.
Gene X is analogous to the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.
Gene Y is correlated with the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
nerdy, xanthic, yucky	n	x	y	745
nerdy, xanthic	n	x	+	135
nerdy, yucky	n	+	y	32
nerdy	n	+	+	2,202
xanthic, yucky	+	x	y	2,406
xanthic	+	x	+	32
yucky	+	+	y	121
wildtype	+	+	+	727
TOTAL =				6,400

The resulting phenotypes are summarized in the table above.

The distance between genes N and Y is 24 cM
The distance between genes N and X is 27 cM
The distance between genes Y and X is 5 cM
The correct gene order determined from these distances is NYX

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes N and X.

b1fc_9bcc

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is analogous to the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene R is analogous to the 'rusty' phenotype. A fruit fly that is homozygous recessive for Gene R has a reddish-brown color, much like rusted iron metal.
Gene Y is correlated with the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
artsy, rusty, yucky	a	r	y	8
artsy, rusty	a	r	+	508
artsy, yucky	a	+	y	159
artsy	a	+	+	1,460
rusty, yucky	+	r	y	1,375
rusty	+	r	+	156
yucky	+	+	y	521
wildtype	+	+	+	13
TOTAL =				4,200

The resulting phenotypes are summarized in the table above.

The distance between genes R and A is 25 cM
The distance between genes R and Y is 32 cM
The distance between genes A and Y is 8 cM
The correct gene order determined from these distances is RAY

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes R and Y.

A. no interference, 0% Incorrect B. ¹/₄ = 0.2500 = 25% Incorrect C. ¹/₂ = 0.5000 = 50% Incorrect D. ³/₄ = 0.7500 = 75% Correct E. complete interference, 100% Incorrect MC

906e_9bcc

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene K is analogous to the 'kidney' phenotype. A fruit fly that is homozygous recessive for Gene K has a body shape that is curved, similar to a kidney bean.
Gene N is correlated with the 'nerdy' phenotype. A fruit fly that is homozygous recessive for Gene N has large, prominent eyes that stand out, much like thick-rimmed glasses.
Gene Y is connected with the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
kidney, nerdy, yucky	k	n	y	2,440
kidney, nerdy	k	n	+	286
kidney, yucky	k	+	y	625
kidney	k	+	+	47
nerdy, yucky	+	n	y	55
nerdy	+	n	+	633
yucky	+	+	y	292
wildtype	+	+	+	2,422
TOTAL =				6,800

The resulting phenotypes are summarized in the table above.

The distance between genes N and K is 20 cM
The distance between genes N and Y is 27 cM
The distance between genes K and Y is 10 cM
The correct gene order determined from these distances is NKY

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes N and Y.

A. no interference, 0% Incorrect B. ¹/₄ = 0.2500 = 25% Correct C. ¹/₂ = 0.5000 = 50% Incorrect D. ³/₄ = 0.7500 = 75% Incorrect E. complete interference, 100% Incorrect MC

ae54_9bcc

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene B is connected with the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene E is linked with the 'eery' phenotype. A fruit fly that is homozygous recessive for Gene E appears to have something off, crooked limbs and other twisted appendages.
Gene P is analogous to the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.

Phenotype	Genotypes			Progeny Count
bumpy, eery, prickly	b	e	p	888
bumpy, eery	b	e	+	517
bumpy, prickly	b	+	p	115
bumpy	b	+	+	2,506
eery, prickly	+	e	p	2,578
eery	+	e	+	131
prickly	+	+	p	549
wildtype	+	+	+	916
TOTAL =				8,200

The resulting phenotypes are summarized in the table above.

The distance between genes B and P is 25 cM
The distance between genes B and E is 35 cM
The distance between genes P and E is 16 cM
The correct gene order determined from these distances is BPE

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes B and E.

A. no interference, 0% Incorrect B. ¹/₄ = 0.2500 = 25% Correct C. ¹/₂ = 0.5000 = 50% Incorrect D. ³/₄ = 0.7500 = 75% Incorrect E. complete interference, 100% Incorrect MC

f200_596f

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene C is connected with the 'chummy' phenotype. A fruit fly that is homozygous recessive for Gene C shows behavior where it always maintains a close distance to other flies.
Gene J is analogous to the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.
Gene N is affiliated with the 'nerdy' phenotype. A fruit fly that is homozygous recessive for Gene N has large, prominent eyes that stand out, much like thick-rimmed glasses.

Phenotype	Genotypes			Progeny Count
chummy, jerky, nerdy	c	j	n	13
chummy, jerky	c	j	+	388
chummy, nerdy	c	+	n	787
chummy	c	+	+	117
jerky, nerdy	+	j	n	108
jerky	+	j	+	738
nerdy	+	+	n	337
wildtype	+	+	+	12
TOTAL =				2,500

The resulting phenotypes are summarized in the table above.

The distance between genes C and J is 30 cM
The distance between genes C and N is 38 cM
The distance between genes J and N is 10 cM
The correct gene order determined from these distances is CJN

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes C and N.

A. no interference, 0% Incorrect B. ¹/₃ = 0.3333 = 33% Incorrect C. ¹/₂ = 0.5000 = 50% Incorrect D. ²/₃ = 0.6667 = 67% Correct E. complete interference, 100% Incorrect MC

aa99_40f0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is affiliated with the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene D is analogous to the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene K is analogous to the 'kidney' phenotype. A fruit fly that is homozygous recessive for Gene K has a body shape that is curved, similar to a kidney bean.

Phenotype	Genotypes			Progeny Count
artsy, dewy, kidney	a	d	k	1,695
artsy, dewy	a	d	+	741
artsy, kidney	a	+	k	171
artsy	a	+	+	468
dewy, kidney	+	d	k	431
dewy	+	d	+	170
kidney	+	+	k	778
wildtype	+	+	+	1,746
TOTAL =				6,200

The resulting phenotypes are summarized in the table above.

The distance between genes A and D is 20 cM
The distance between genes A and K is 39 cM
The distance between genes D and K is 30 cM
The correct gene order determined from these distances is ADK

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes A and K.

f2ae_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is related to the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene X is linked with the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.
Gene Y is associated with the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
artsy, xanthic, yucky	a	x	y	49
artsy, xanthic	a	x	+	310
artsy, yucky	a	+	y	2,168
artsy	a	+	+	390
xanthic, yucky	+	x	y	393
xanthic	+	x	+	2,153
yucky	+	+	y	299
wildtype	+	+	+	38
TOTAL =				5,800

The resulting phenotypes are summarized in the table above.

The distance between genes A and X is 12 cM
The distance between genes A and Y is 24 cM
The distance between genes X and Y is 15 cM
The correct gene order determined from these distances is AXY

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes A and Y.

be3e_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene H is linked with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene M is associated with the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.
Gene N is correlated with the 'nerdy' phenotype. A fruit fly that is homozygous recessive for Gene N has large, prominent eyes that stand out, much like thick-rimmed glasses.

Phenotype	Genotypes			Progeny Count
horsey, mushy, nerdy	h	m	n	215
horsey, mushy	h	m	+	708
horsey, nerdy	h	+	n	14
horsey	h	+	+	1,456
mushy, nerdy	+	m	n	1,448
mushy	+	m	+	10
nerdy	+	+	n	708
wildtype	+	+	+	241
TOTAL =				4,800

The resulting phenotypes are summarized in the table above.

The distance between genes H and N is 10 cM
The distance between genes H and M is 39 cM
The distance between genes N and M is 30 cM
The correct gene order determined from these distances is HNM

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes H and M.

4e00_40f0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene E is analogous to the 'eery' phenotype. A fruit fly that is homozygous recessive for Gene E appears to have something off, crooked limbs and other twisted appendages.
Gene F is affiliated with the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.
Gene K is correlated with the 'kidney' phenotype. A fruit fly that is homozygous recessive for Gene K has a body shape that is curved, similar to a kidney bean.

Phenotype	Genotypes			Progeny Count
eery, fuzzy, kidney	e	f	k	384
eery, fuzzy	e	f	+	1,517
eery, kidney	e	+	k	122
eery	e	+	+	9
fuzzy, kidney	+	f	k	11
fuzzy	+	f	+	98
kidney	+	+	k	1,463
wildtype	+	+	+	396
TOTAL =				4,000

The resulting phenotypes are summarized in the table above.

The distance between genes E and F is 6 cM
The distance between genes E and K is 25 cM
The distance between genes F and K is 20 cM
The correct gene order determined from these distances is EFK

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes E and K.

c3bf_9bcc

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is associated with the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene P is connected with the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.
Gene T is correlated with the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.

Phenotype	Genotypes			Progeny Count
artsy, prickly, tipsy	a	p	t	621
artsy, prickly	a	p	+	2,411
artsy, tipsy	a	+	t	46
artsy	a	+	+	893
prickly, tipsy	+	p	t	1,003
prickly	+	p	+	33
tipsy	+	+	t	2,329
wildtype	+	+	+	564
TOTAL =				7,900

The resulting phenotypes are summarized in the table above.

The distance between genes P and A is 25 cM
The distance between genes P and T is 39 cM
The distance between genes A and T is 16 cM
The correct gene order determined from these distances is PAT

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes P and T.

A. no interference, 0% Incorrect B. ¹/₄ = 0.2500 = 25% Incorrect C. ¹/₂ = 0.5000 = 50% Incorrect D. ³/₄ = 0.7500 = 75% Correct E. complete interference, 100% Incorrect MC

5ea6_10af

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene H is connected with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene W is affiliated with the 'waxy' phenotype. A fruit fly that is homozygous recessive for Gene W has a thick protective layer that is water resistant and opague.
Gene X is linked with the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.

Phenotype	Genotypes			Progeny Count
horsey, waxy, xanthic	h	w	x	668
horsey, waxy	h	w	+	56
horsey, xanthic	h	+	x	345
horsey	h	+	+	1,822
waxy, xanthic	+	w	x	1,832
waxy	+	w	+	351
xanthic	+	+	x	60
wildtype	+	+	+	666
TOTAL =				5,800

The resulting phenotypes are summarized in the table above.

The distance between genes H and W is 25 cM
The distance between genes H and X is 35 cM
The distance between genes W and X is 14 cM
The correct gene order determined from these distances is HWX

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes H and X.

A. no interference, 0% Incorrect B. ¹/₇ = 0.1429 = 14% Incorrect C. ²/₇ = 0.2857 = 29% Incorrect D. ³/₇ = 0.4286 = 43% Correct E. ¹/₂ = 0.5000 = 50% Incorrect F. ⁴/₇ = 0.5714 = 57% Incorrect G. ⁵/₇ = 0.7143 = 71% Incorrect H. ⁶/₇ = 0.8571 = 86% Incorrect I. complete interference, 100% Incorrect MC

ab5c_10af

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene J is affiliated with the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.
Gene P is linked with the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.
Gene W is linked with the 'waxy' phenotype. A fruit fly that is homozygous recessive for Gene W has a thick protective layer that is water resistant and opague.

Phenotype	Genotypes			Progeny Count
jerky, prickly, waxy	j	p	w	67
jerky, prickly	j	p	+	18
jerky, waxy	j	+	w	458
jerky	j	+	+	846
prickly, waxy	+	p	w	848
prickly	+	p	+	480
waxy	+	+	w	24
wildtype	+	+	+	59
TOTAL =				2,800

The resulting phenotypes are summarized in the table above.

The distance between genes J and P is 6 cM
The distance between genes J and W is 38 cM
The distance between genes P and W is 35 cM
The correct gene order determined from these distances is JPW

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes J and W.

eb5a_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene N is correlated with the 'nerdy' phenotype. A fruit fly that is homozygous recessive for Gene N has large, prominent eyes that stand out, much like thick-rimmed glasses.
Gene T is related to the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.
Gene W is associated with the 'waxy' phenotype. A fruit fly that is homozygous recessive for Gene W has a thick protective layer that is water resistant and opague.

Phenotype	Genotypes			Progeny Count
nerdy, tipsy, waxy	n	t	w	926
nerdy, tipsy	n	t	+	138
nerdy, waxy	n	+	w	2,350
nerdy	n	+	+	436
tipsy, waxy	+	t	w	461
tipsy	+	t	+	2,369
waxy	+	+	w	135
wildtype	+	+	+	985
TOTAL =				7,800

The resulting phenotypes are summarized in the table above.

The distance between genes T and N is 28 cM
The distance between genes T and W is 36 cM
The distance between genes N and W is 15 cM
The correct gene order determined from these distances is TNW

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes T and W.

5621_84bd

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is connected with the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene R is linked with the 'rusty' phenotype. A fruit fly that is homozygous recessive for Gene R has a reddish-brown color, much like rusted iron metal.
Gene W is analogous to the 'waxy' phenotype. A fruit fly that is homozygous recessive for Gene W has a thick protective layer that is water resistant and opague.

Phenotype	Genotypes			Progeny Count
artsy, rusty, waxy	a	r	w	2,175
artsy, rusty	a	r	+	321
artsy, waxy	a	+	w	814
artsy	a	+	+	33
rusty, waxy	+	r	w	34
rusty	+	r	+	794
waxy	+	+	w	349
wildtype	+	+	+	2,180
TOTAL =				6,700

The resulting phenotypes are summarized in the table above.

The distance between genes R and A is 25 cM
The distance between genes R and W is 34 cM
The distance between genes A and W is 11 cM
The correct gene order determined from these distances is RAW

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes R and W.

A. no interference, 0% Incorrect B. ¹/₁₁ = 0.0909 = 9% Incorrect C. ³/₁₁ = 0.2727 = 27% Incorrect D. ⁴/₁₁ = 0.3636 = 36% Incorrect E. ⁵/₁₁ = 0.4545 = 45% Incorrect F. ¹/₂ = 0.5000 = 50% Incorrect G. ⁷/₁₁ = 0.6364 = 64% Correct H. ⁹/₁₁ = 0.8182 = 82% Incorrect I. complete interference, 100% Incorrect MC

8031_2477

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene B is linked with the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene D is associated with the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene F is related to the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.

Phenotype	Genotypes			Progeny Count
bumpy, dewy, fuzzy	b	d	f	2,731
bumpy, dewy	b	d	+	1,262
bumpy, fuzzy	b	+	f	55
bumpy	b	+	+	428
dewy, fuzzy	+	d	f	408
dewy	+	d	+	77
fuzzy	+	+	f	1,246
wildtype	+	+	+	2,593
TOTAL =				8,800

The resulting phenotypes are summarized in the table above.

The distance between genes B and D is 11 cM
The distance between genes B and F is 38 cM
The distance between genes D and F is 30 cM
The correct gene order determined from these distances is BDF

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes B and F.

d2db_10af

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene B is connected with the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene F is linked with the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.
Gene Y is related to the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
bumpy, fuzzy, yucky	b	f	y	302
bumpy, fuzzy	b	f	+	12
bumpy, yucky	b	+	y	38
bumpy	b	+	+	534
fuzzy, yucky	+	f	y	564
fuzzy	+	f	+	34
yucky	+	+	y	6
wildtype	+	+	+	310
TOTAL =				1,800

The resulting phenotypes are summarized in the table above.

The distance between genes B and F is 35 cM
The distance between genes B and Y is 38 cM
The distance between genes F and Y is 5 cM
The correct gene order determined from these distances is BFY

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes B and Y.

8083_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene C is affiliated with the 'chummy' phenotype. A fruit fly that is homozygous recessive for Gene C shows behavior where it always maintains a close distance to other flies.
Gene J is analogous to the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.
Gene W is associated with the 'waxy' phenotype. A fruit fly that is homozygous recessive for Gene W has a thick protective layer that is water resistant and opague.

Phenotype	Genotypes			Progeny Count
chummy, jerky, waxy	c	j	w	137
chummy, jerky	c	j	+	2,834
chummy, waxy	c	+	w	762
chummy	c	+	+	668
jerky, waxy	+	j	w	637
jerky	+	j	+	717
waxy	+	+	w	2,821
wildtype	+	+	+	124
TOTAL =				8,700

The resulting phenotypes are summarized in the table above.

The distance between genes C and W is 20 cM
The distance between genes C and J is 32 cM
The distance between genes W and J is 18 cM
The correct gene order determined from these distances is CWJ

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes C and J.

a936_10af

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene J is correlated with the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.
Gene M is analogous to the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.
Gene R is related to the 'rusty' phenotype. A fruit fly that is homozygous recessive for Gene R has a reddish-brown color, much like rusted iron metal.

Phenotype	Genotypes			Progeny Count
jerky, mushy, rusty	j	m	r	46
jerky, mushy	j	m	+	267
jerky, rusty	j	+	r	3,427
jerky	j	+	+	901
mushy, rusty	+	m	r	847
mushy	+	m	+	3,381
rusty	+	+	r	285
wildtype	+	+	+	46
TOTAL =				9,200

The resulting phenotypes are summarized in the table above.

The distance between genes J and M is 7 cM
The distance between genes J and R is 25 cM
The distance between genes M and R is 20 cM
The correct gene order determined from these distances is JMR

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes J and R.

ff6c_e662

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene D is correlated with the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene J is analogous to the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.
Gene X is analogous to the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.

Phenotype	Genotypes			Progeny Count
dewy, jerky, xanthic	d	j	x	124
dewy, jerky	d	j	+	1,609
dewy, xanthic	d	+	x	308
dewy	d	+	+	840
jerky, xanthic	+	j	x	813
jerky	+	j	+	301
xanthic	+	+	x	1,668
wildtype	+	+	+	137
TOTAL =				5,800

The resulting phenotypes are summarized in the table above.

The distance between genes D and X is 15 cM
The distance between genes D and J is 39 cM
The distance between genes X and J is 33 cM
The correct gene order determined from these distances is DXJ

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes D and J.

3ae5_9bcc

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene D is connected with the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene W is affiliated with the 'waxy' phenotype. A fruit fly that is homozygous recessive for Gene W has a thick protective layer that is water resistant and opague.
Gene X is related to the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.

Phenotype	Genotypes			Progeny Count
dewy, waxy, xanthic	d	w	x	57
dewy, waxy	d	w	+	2,437
dewy, xanthic	d	+	x	847
dewy	d	+	+	236
waxy, xanthic	+	w	x	232
waxy	+	w	+	845
xanthic	+	+	x	2,495
wildtype	+	+	+	51
TOTAL =				7,200

The resulting phenotypes are summarized in the table above.

The distance between genes D and X is 25 cM
The distance between genes D and W is 30 cM
The distance between genes X and W is 8 cM
The correct gene order determined from these distances is DXW

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes D and W.

A. no interference, 0% Incorrect B. ¹/₄ = 0.2500 = 25% Correct C. ¹/₂ = 0.5000 = 50% Incorrect D. ³/₄ = 0.7500 = 75% Incorrect E. complete interference, 100% Incorrect MC

80a5_10af

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is linked with the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene H is analogous to the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene N is associated with the 'nerdy' phenotype. A fruit fly that is homozygous recessive for Gene N has large, prominent eyes that stand out, much like thick-rimmed glasses.

Phenotype	Genotypes			Progeny Count
artsy, horsey, nerdy	a	h	n	1,347
artsy, horsey	a	h	+	120
artsy, nerdy	a	+	n	285
artsy	a	+	+	2,380
horsey, nerdy	+	h	n	2,492
horsey	+	h	+	303
nerdy	+	+	n	132
wildtype	+	+	+	1,341
TOTAL =				8,400

The resulting phenotypes are summarized in the table above.

The distance between genes A and H is 35 cM
The distance between genes A and N is 39 cM
The distance between genes H and N is 10 cM
The correct gene order determined from these distances is AHN

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes A and N.

faa7_c58a

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene D is correlated with the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene F is correlated with the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.
Gene J is affiliated with the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.

Phenotype	Genotypes			Progeny Count
dewy, fuzzy, jerky	d	f	j	56
dewy, fuzzy	d	f	+	8
dewy, jerky	d	+	j	595
dewy	d	+	+	1,377
fuzzy, jerky	+	f	j	1,323
fuzzy	+	f	+	585
jerky	+	+	j	12
wildtype	+	+	+	44
TOTAL =				4,000

The resulting phenotypes are summarized in the table above.

The distance between genes D and F is 3 cM
The distance between genes D and J is 32 cM
The distance between genes F and J is 30 cM
The correct gene order determined from these distances is DFJ

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes D and J.

2437_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene C is related to the 'chummy' phenotype. A fruit fly that is homozygous recessive for Gene C shows behavior where it always maintains a close distance to other flies.
Gene D is linked with the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene K is affiliated with the 'kidney' phenotype. A fruit fly that is homozygous recessive for Gene K has a body shape that is curved, similar to a kidney bean.

Phenotype	Genotypes			Progeny Count
chummy, dewy, kidney	c	d	k	1,841
chummy, dewy	c	d	+	43
chummy, kidney	c	+	k	231
chummy	c	+	+	446
dewy, kidney	+	d	k	412
dewy	+	d	+	211
kidney	+	+	k	35
wildtype	+	+	+	1,981
TOTAL =				5,200

The resulting phenotypes are summarized in the table above.

The distance between genes C and K is 18 cM
The distance between genes C and D is 25 cM
The distance between genes K and D is 10 cM
The correct gene order determined from these distances is CKD

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes C and D.

c89d_e662

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene C is analogous to the 'chummy' phenotype. A fruit fly that is homozygous recessive for Gene C shows behavior where it always maintains a close distance to other flies.
Gene H is related to the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene M is related to the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.

Phenotype	Genotypes			Progeny Count
chummy, horsey, mushy	c	h	m	704
chummy, horsey	c	h	+	284
chummy, mushy	c	+	m	63
chummy	c	+	+	2,427
horsey, mushy	+	h	m	2,403
horsey	+	h	+	75
mushy	+	+	m	268
wildtype	+	+	+	676
TOTAL =				6,900

The resulting phenotypes are summarized in the table above.

The distance between genes C and M is 22 cM
The distance between genes C and H is 28 cM
The distance between genes M and H is 10 cM
The correct gene order determined from these distances is CMH

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes C and H.

6a2f_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene H is connected with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene N is related to the 'nerdy' phenotype. A fruit fly that is homozygous recessive for Gene N has large, prominent eyes that stand out, much like thick-rimmed glasses.
Gene Y is affiliated with the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
horsey, nerdy, yucky	h	n	y	175
horsey, nerdy	h	n	+	359
horsey, yucky	h	+	y	18
horsey	h	+	+	53
nerdy, yucky	+	n	y	79
nerdy	+	n	+	30
yucky	+	+	y	325
wildtype	+	+	+	161
TOTAL =				1,200

The resulting phenotypes are summarized in the table above.

The distance between genes N and H is 15 cM
The distance between genes N and Y is 39 cM
The distance between genes H and Y is 32 cM
The correct gene order determined from these distances is NHY

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes N and Y.

e253_e662

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene M is correlated with the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.
Gene P is associated with the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.
Gene T is related to the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.

Phenotype	Genotypes			Progeny Count
mushy, prickly, tipsy	m	p	t	358
mushy, prickly	m	p	+	96
mushy, tipsy	m	+	t	1,089
mushy	m	+	+	343
prickly, tipsy	+	p	t	286
prickly	+	p	+	1,057
tipsy	+	+	t	89
wildtype	+	+	+	382
TOTAL =				3,700

The resulting phenotypes are summarized in the table above.

The distance between genes P and M is 25 cM
The distance between genes P and T is 37 cM
The distance between genes M and T is 22 cM
The correct gene order determined from these distances is PMT

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes P and T.

4586_2477

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is related to the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene B is linked with the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene D is related to the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.

Phenotype	Genotypes			Progeny Count
artsy, bumpy, dewy	a	b	d	58
artsy, bumpy	a	b	+	122
artsy, dewy	a	+	d	6
artsy	a	+	+	400
bumpy, dewy	+	b	d	428
bumpy	+	b	+	6
dewy	+	+	d	130
wildtype	+	+	+	50
TOTAL =				1,200

The resulting phenotypes are summarized in the table above.

The distance between genes A and D is 10 cM
The distance between genes A and B is 30 cM
The distance between genes D and B is 22 cM
The correct gene order determined from these distances is ADB

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes A and B.

27ec_23c4

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene C is related to the 'chummy' phenotype. A fruit fly that is homozygous recessive for Gene C shows behavior where it always maintains a close distance to other flies.
Gene E is linked with the 'eery' phenotype. A fruit fly that is homozygous recessive for Gene E appears to have something off, crooked limbs and other twisted appendages.
Gene J is related to the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.

Phenotype	Genotypes			Progeny Count
chummy, eery, jerky	c	e	j	284
chummy, eery	c	e	+	2,240
chummy, jerky	c	+	j	51
chummy	c	+	+	745
eery, jerky	+	e	j	740
eery	+	e	+	48
jerky	+	+	j	2,215
wildtype	+	+	+	277
TOTAL =				6,600

The resulting phenotypes are summarized in the table above.

The distance between genes E and C is 24 cM
The distance between genes E and J is 31 cM
The distance between genes C and J is 10 cM
The correct gene order determined from these distances is ECJ

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes E and J.

3080_596f

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is analogous to the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene B is connected with the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene X is affiliated with the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.

Phenotype	Genotypes			Progeny Count
artsy, bumpy, xanthic	a	b	x	198
artsy, bumpy	a	b	+	1,604
artsy, xanthic	a	+	x	14
artsy	a	+	+	305
bumpy, xanthic	+	b	x	304
bumpy	+	b	+	7
xanthic	+	+	x	1,567
wildtype	+	+	+	201
TOTAL =				4,200

The resulting phenotypes are summarized in the table above.

The distance between genes B and A is 15 cM
The distance between genes B and X is 24 cM
The distance between genes A and X is 10 cM
The correct gene order determined from these distances is BAX

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes B and X.

A. no interference, 0% Incorrect B. ¹/₃ = 0.3333 = 33% Incorrect C. ¹/₂ = 0.5000 = 50% Incorrect D. ²/₃ = 0.6667 = 67% Correct E. complete interference, 100% Incorrect MC

7792_c58a

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene D is associated with the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene P is correlated with the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.
Gene T is related to the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.

Phenotype	Genotypes			Progeny Count
dewy, prickly, tipsy	d	p	t	54
dewy, prickly	d	p	+	855
dewy, tipsy	d	+	t	240
dewy	d	+	+	1,980
prickly, tipsy	+	p	t	1,895
prickly	+	p	+	225
tipsy	+	+	t	912
wildtype	+	+	+	39
TOTAL =				6,200

The resulting phenotypes are summarized in the table above.

The distance between genes P and D is 30 cM
The distance between genes P and T is 36 cM
The distance between genes D and T is 9 cM
The correct gene order determined from these distances is PDT

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes P and T.

9d08_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene D is related to the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene H is correlated with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene W is linked with the 'waxy' phenotype. A fruit fly that is homozygous recessive for Gene W has a thick protective layer that is water resistant and opague.

Phenotype	Genotypes			Progeny Count
dewy, horsey, waxy	d	h	w	127
dewy, horsey	d	h	+	892
dewy, waxy	d	+	w	2,732
dewy	d	+	+	511
horsey, waxy	+	h	w	521
horsey	+	h	+	2,772
waxy	+	+	w	914
wildtype	+	+	+	131
TOTAL =				8,600

The resulting phenotypes are summarized in the table above.

The distance between genes D and H is 24 cM
The distance between genes D and W is 33 cM
The distance between genes H and W is 15 cM
The correct gene order determined from these distances is DHW

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes D and W.

ca5c_9c3b

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene J is associated with the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.
Gene M is affiliated with the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.
Gene N is associated with the 'nerdy' phenotype. A fruit fly that is homozygous recessive for Gene N has large, prominent eyes that stand out, much like thick-rimmed glasses.

Phenotype	Genotypes			Progeny Count
jerky, mushy, nerdy	j	m	n	1,238
jerky, mushy	j	m	+	85
jerky, nerdy	j	+	n	427
jerky	j	+	+	288
mushy, nerdy	+	m	n	300
mushy	+	m	+	455
nerdy	+	+	n	83
wildtype	+	+	+	1,324
TOTAL =				4,200

The resulting phenotypes are summarized in the table above.

The distance between genes J and N is 18 cM
The distance between genes J and M is 35 cM
The distance between genes N and M is 25 cM
The correct gene order determined from these distances is JNM

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes J and M.

6168_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene C is connected with the 'chummy' phenotype. A fruit fly that is homozygous recessive for Gene C shows behavior where it always maintains a close distance to other flies.
Gene D is related to the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene W is linked with the 'waxy' phenotype. A fruit fly that is homozygous recessive for Gene W has a thick protective layer that is water resistant and opague.

Phenotype	Genotypes			Progeny Count
chummy, dewy, waxy	c	d	w	156
chummy, dewy	c	d	+	451
chummy, waxy	c	+	w	1,929
chummy	c	+	+	866
dewy, waxy	+	d	w	868
dewy	+	d	+	1,913
waxy	+	+	w	467
wildtype	+	+	+	150
TOTAL =				6,800

The resulting phenotypes are summarized in the table above.

The distance between genes C and D is 18 cM
The distance between genes C and W is 39 cM
The distance between genes D and W is 30 cM
The correct gene order determined from these distances is CDW

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes C and W.

d469_23c4

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene F is analogous to the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.
Gene X is affiliated with the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.
Gene Y is analogous to the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
fuzzy, xanthic, yucky	f	x	y	121
fuzzy, xanthic	f	x	+	915
fuzzy, yucky	f	+	y	28
fuzzy	f	+	+	1,952
xanthic, yucky	+	x	y	1,824
xanthic	+	x	+	31
yucky	+	+	y	914
wildtype	+	+	+	115
TOTAL =				5,900

The resulting phenotypes are summarized in the table above.

The distance between genes F and Y is 5 cM
The distance between genes F and X is 35 cM
The distance between genes Y and X is 32 cM
The correct gene order determined from these distances is FYX

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes F and X.

fcd4_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene T is related to the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.
Gene X is connected with the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.
Gene Y is connected with the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
tipsy, xanthic, yucky	t	x	y	1,683
tipsy, xanthic	t	x	+	5
tipsy, yucky	t	+	y	117
tipsy	t	+	+	187
xanthic, yucky	+	x	y	193
xanthic	+	x	+	103
yucky	+	+	y	15
wildtype	+	+	+	1,697
TOTAL =				4,000

The resulting phenotypes are summarized in the table above.

The distance between genes T and Y is 10 cM
The distance between genes T and X is 15 cM
The distance between genes Y and X is 6 cM
The correct gene order determined from these distances is TYX

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes T and X.

c9f4_c5f9

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene E is linked with the 'eery' phenotype. A fruit fly that is homozygous recessive for Gene E appears to have something off, crooked limbs and other twisted appendages.
Gene P is affiliated with the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.
Gene R is correlated with the 'rusty' phenotype. A fruit fly that is homozygous recessive for Gene R has a reddish-brown color, much like rusted iron metal.

Phenotype	Genotypes			Progeny Count
eery, prickly, rusty	e	p	r	583
eery, prickly	e	p	+	233
eery, rusty	e	+	r	99
eery	e	+	+	7
prickly, rusty	+	p	r	2
prickly	+	p	+	90
rusty	+	+	r	208
wildtype	+	+	+	578
TOTAL =				1,800

The resulting phenotypes are summarized in the table above.

The distance between genes P and E is 11 cM
The distance between genes P and R is 35 cM
The distance between genes E and R is 25 cM
The correct gene order determined from these distances is PER

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes P and R.

A. no interference, 0% Incorrect B. ¹/₁₁ = 0.0909 = 9% Incorrect C. ²/₁₁ = 0.1818 = 18% Incorrect D. ³/₁₁ = 0.2727 = 27% Incorrect E. ⁵/₁₁ = 0.4545 = 45% Incorrect F. ¹/₂ = 0.5000 = 50% Incorrect G. ⁷/₁₁ = 0.6364 = 64% Incorrect H. ⁹/₁₁ = 0.8182 = 82% Correct I. complete interference, 100% Incorrect MC

d902_596f

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene E is connected with the 'eery' phenotype. A fruit fly that is homozygous recessive for Gene E appears to have something off, crooked limbs and other twisted appendages.
Gene M is affiliated with the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.
Gene T is linked with the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.

Phenotype	Genotypes			Progeny Count
eery, mushy, tipsy	e	m	t	334
eery, mushy	e	m	+	1,743
eery, tipsy	e	+	t	21
eery	e	+	+	222
mushy, tipsy	+	m	t	201
mushy	+	m	+	26
tipsy	+	+	t	1,829
wildtype	+	+	+	324
TOTAL =				4,700

The resulting phenotypes are summarized in the table above.

The distance between genes M and E is 10 cM
The distance between genes M and T is 23 cM
The distance between genes E and T is 15 cM
The correct gene order determined from these distances is MET

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes M and T.

A. no interference, 0% Incorrect B. ¹/₃ = 0.3333 = 33% Correct C. ¹/₂ = 0.5000 = 50% Incorrect D. ²/₃ = 0.6667 = 67% Incorrect E. complete interference, 100% Incorrect MC

8868_596f

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is linked with the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene T is affiliated with the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.
Gene X is analogous to the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.

Phenotype	Genotypes			Progeny Count
artsy, tipsy, xanthic	a	t	x	717
artsy, tipsy	a	t	+	201
artsy, xanthic	a	+	x	1,587
artsy	a	+	+	47
tipsy, xanthic	+	t	x	55
tipsy	+	t	+	1,575
xanthic	+	+	x	207
wildtype	+	+	+	711
TOTAL =				5,100

The resulting phenotypes are summarized in the table above.

The distance between genes A and X is 10 cM
The distance between genes A and T is 36 cM
The distance between genes X and T is 30 cM
The correct gene order determined from these distances is AXT

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes A and T.

A. no interference, 0% Incorrect B. ¹/₃ = 0.3333 = 33% Correct C. ¹/₂ = 0.5000 = 50% Incorrect D. ²/₃ = 0.6667 = 67% Incorrect E. complete interference, 100% Incorrect MC

3491_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene D is linked with the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene H is associated with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene R is connected with the 'rusty' phenotype. A fruit fly that is homozygous recessive for Gene R has a reddish-brown color, much like rusted iron metal.

Phenotype	Genotypes			Progeny Count
dewy, horsey, rusty	d	h	r	1,879
dewy, horsey	d	h	+	364
dewy, rusty	d	+	r	97
dewy	d	+	+	667
horsey, rusty	+	h	r	593
horsey	+	h	+	83
rusty	+	+	r	356
wildtype	+	+	+	1,961
TOTAL =				6,000

The resulting phenotypes are summarized in the table above.

The distance between genes D and H is 24 cM
The distance between genes D and R is 33 cM
The distance between genes H and R is 15 cM
The correct gene order determined from these distances is DHR

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes D and R.

5558_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is related to the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene J is related to the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.
Gene K is associated with the 'kidney' phenotype. A fruit fly that is homozygous recessive for Gene K has a body shape that is curved, similar to a kidney bean.

Phenotype	Genotypes			Progeny Count
artsy, jerky, kidney	a	j	k	350
artsy, jerky	a	j	+	25
artsy, kidney	a	+	k	288
artsy	a	+	+	2,580
jerky, kidney	+	j	k	2,476
jerky	+	j	+	288
kidney	+	+	k	39
wildtype	+	+	+	354
TOTAL =				6,400

The resulting phenotypes are summarized in the table above.

The distance between genes A and J is 12 cM
The distance between genes A and K is 20 cM
The distance between genes J and K is 10 cM
The correct gene order determined from these distances is AJK

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes A and K.

915e_23c4

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene F is connected with the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.
Gene M is analogous to the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.
Gene T is related to the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.

Phenotype	Genotypes			Progeny Count
fuzzy, mushy, tipsy	f	m	t	406
fuzzy, mushy	f	m	+	697
fuzzy, tipsy	f	+	t	120
fuzzy	f	+	+	2,113
mushy, tipsy	+	m	t	2,012
mushy	+	m	+	111
tipsy	+	+	t	722
wildtype	+	+	+	419
TOTAL =				6,600

The resulting phenotypes are summarized in the table above.

The distance between genes F and T is 16 cM
The distance between genes F and M is 34 cM
The distance between genes T and M is 25 cM
The correct gene order determined from these distances is FTM

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes F and M.

250d_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene B is related to the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene J is correlated with the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.
Gene K is connected with the 'kidney' phenotype. A fruit fly that is homozygous recessive for Gene K has a body shape that is curved, similar to a kidney bean.

Phenotype	Genotypes			Progeny Count
bumpy, jerky, kidney	b	j	k	1,383
bumpy, jerky	b	j	+	137
bumpy, kidney	b	+	k	7
bumpy	b	+	+	87
jerky, kidney	+	j	k	89
jerky	+	j	+	9
kidney	+	+	k	167
wildtype	+	+	+	1,321
TOTAL =				3,200

The resulting phenotypes are summarized in the table above.

The distance between genes B and J is 6 cM
The distance between genes B and K is 15 cM
The distance between genes J and K is 10 cM
The correct gene order determined from these distances is BJK

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes B and K.

c74e_596f

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene B is associated with the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene E is related to the 'eery' phenotype. A fruit fly that is homozygous recessive for Gene E appears to have something off, crooked limbs and other twisted appendages.
Gene R is linked with the 'rusty' phenotype. A fruit fly that is homozygous recessive for Gene R has a reddish-brown color, much like rusted iron metal.

Phenotype	Genotypes			Progeny Count
bumpy, eery, rusty	b	e	r	10
bumpy, eery	b	e	+	912
bumpy, rusty	b	+	r	140
bumpy	b	+	+	431
eery, rusty	+	e	r	439
eery	+	e	+	130
rusty	+	+	r	918
wildtype	+	+	+	20
TOTAL =				3,000

The resulting phenotypes are summarized in the table above.

The distance between genes B and R is 10 cM
The distance between genes B and E is 38 cM
The distance between genes R and E is 30 cM
The correct gene order determined from these distances is BRE

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes B and E.

A. no interference, 0% Incorrect B. ¹/₃ = 0.3333 = 33% Incorrect C. ¹/₂ = 0.5000 = 50% Incorrect D. ²/₃ = 0.6667 = 67% Correct E. complete interference, 100% Incorrect MC

850d_c58a

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene F is associated with the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.
Gene N is analogous to the 'nerdy' phenotype. A fruit fly that is homozygous recessive for Gene N has large, prominent eyes that stand out, much like thick-rimmed glasses.
Gene X is linked with the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.

Phenotype	Genotypes			Progeny Count
fuzzy, nerdy, xanthic	f	n	x	1,030
fuzzy, nerdy	f	n	+	46
fuzzy, xanthic	f	+	x	230
fuzzy	f	+	+	6
nerdy, xanthic	+	n	x	7
nerdy	+	n	+	225
xanthic	+	+	x	71
wildtype	+	+	+	985
TOTAL =				2,600

The resulting phenotypes are summarized in the table above.

The distance between genes N and F is 18 cM
The distance between genes N and X is 22 cM
The distance between genes F and X is 5 cM
The correct gene order determined from these distances is NFX

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes N and X.

42b0_38cc

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene D is correlated with the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene M is linked with the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.
Gene Y is analogous to the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
dewy, mushy, yucky	d	m	y	2,714
dewy, mushy	d	m	+	37
dewy, yucky	d	+	y	144
dewy	d	+	+	893
mushy, yucky	+	m	y	931
mushy	+	m	+	160
yucky	+	+	y	39
wildtype	+	+	+	2,682
TOTAL =				7,600

The resulting phenotypes are summarized in the table above.

The distance between genes D and Y is 25 cM
The distance between genes D and M is 28 cM
The distance between genes Y and M is 5 cM
The correct gene order determined from these distances is DYM

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes D and M.

6a47_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene C is analogous to the 'chummy' phenotype. A fruit fly that is homozygous recessive for Gene C shows behavior where it always maintains a close distance to other flies.
Gene J is correlated with the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.
Gene T is connected with the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.

Phenotype	Genotypes			Progeny Count
chummy, jerky, tipsy	c	j	t	78
chummy, jerky	c	j	+	1,510
chummy, tipsy	c	+	t	617
chummy	c	+	+	260
jerky, tipsy	+	j	t	315
jerky	+	j	+	608
tipsy	+	+	t	1,515
wildtype	+	+	+	97
TOTAL =				5,000

The resulting phenotypes are summarized in the table above.

The distance between genes C and T is 28 cM
The distance between genes C and J is 36 cM
The distance between genes T and J is 15 cM
The correct gene order determined from these distances is CTJ

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes C and J.

85b1_38cc

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is linked with the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene B is correlated with the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene E is linked with the 'eery' phenotype. A fruit fly that is homozygous recessive for Gene E appears to have something off, crooked limbs and other twisted appendages.

Phenotype	Genotypes			Progeny Count
artsy, bumpy, eery	a	b	e	26
artsy, bumpy	a	b	+	1,702
artsy, eery	a	+	e	597
artsy	a	+	+	103
bumpy, eery	+	b	e	89
bumpy	+	b	+	555
eery	+	+	e	1,706
wildtype	+	+	+	22
TOTAL =				4,800

The resulting phenotypes are summarized in the table above.

The distance between genes A and E is 25 cM
The distance between genes A and B is 28 cM
The distance between genes E and B is 5 cM
The correct gene order determined from these distances is AEB

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes A and B.

97b6_38cc

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene C is connected with the 'chummy' phenotype. A fruit fly that is homozygous recessive for Gene C shows behavior where it always maintains a close distance to other flies.
Gene E is affiliated with the 'eery' phenotype. A fruit fly that is homozygous recessive for Gene E appears to have something off, crooked limbs and other twisted appendages.
Gene F is related to the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.

Phenotype	Genotypes			Progeny Count
chummy, eery, fuzzy	c	e	f	28
chummy, eery	c	e	+	137
chummy, fuzzy	c	+	f	750
chummy	c	+	+	2,146
eery, fuzzy	+	e	f	2,256
eery	+	e	+	738
fuzzy	+	+	f	111
wildtype	+	+	+	34
TOTAL =				6,200

The resulting phenotypes are summarized in the table above.

The distance between genes E and C is 5 cM
The distance between genes E and F is 28 cM
The distance between genes C and F is 25 cM
The correct gene order determined from these distances is ECF

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes E and F.

2088_596f

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene B is affiliated with the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene M is linked with the 'mushy' phenotype. A fruit fly that is homozygous recessive for Gene M feels soft to the touch and unusually squishy, unlike the usual firmness.
Gene X is affiliated with the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.

Phenotype	Genotypes			Progeny Count
bumpy, mushy, xanthic	b	m	x	14
bumpy, mushy	b	m	+	71
bumpy, xanthic	b	+	x	633
bumpy	b	+	+	1,883
mushy, xanthic	+	m	x	1,887
mushy	+	m	+	641
xanthic	+	+	x	59
wildtype	+	+	+	12
TOTAL =				5,200

The resulting phenotypes are summarized in the table above.

The distance between genes M and B is 3 cM
The distance between genes M and X is 27 cM
The distance between genes B and X is 25 cM
The correct gene order determined from these distances is MBX

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes M and X.

A. no interference, 0% Incorrect B. ¹/₃ = 0.3333 = 33% Correct C. ¹/₂ = 0.5000 = 50% Incorrect D. ²/₃ = 0.6667 = 67% Incorrect E. complete interference, 100% Incorrect MC

5c70_596f

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene B is connected with the 'bumpy' phenotype. A fruit fly that is homozygous recessive for Gene B has a skin texture that is not smooth, but rough with small bumps all over.
Gene C is associated with the 'chummy' phenotype. A fruit fly that is homozygous recessive for Gene C shows behavior where it always maintains a close distance to other flies.
Gene J is correlated with the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.

Phenotype	Genotypes			Progeny Count
bumpy, chummy, jerky	b	c	j	19
bumpy, chummy	b	c	+	1,290
bumpy, jerky	b	+	j	444
bumpy	b	+	+	100
chummy, jerky	+	c	j	85
chummy	+	c	+	444
jerky	+	+	j	1,300
wildtype	+	+	+	18
TOTAL =				3,700

The resulting phenotypes are summarized in the table above.

The distance between genes B and J is 25 cM
The distance between genes B and C is 29 cM
The distance between genes J and C is 6 cM
The correct gene order determined from these distances is BJC

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes B and C.

A. no interference, 0% Incorrect B. ¹/₃ = 0.3333 = 33% Correct C. ¹/₂ = 0.5000 = 50% Incorrect D. ²/₃ = 0.6667 = 67% Incorrect E. complete interference, 100% Incorrect MC

4c06_e662

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene F is linked with the 'fuzzy' phenotype. A fruit fly that is homozygous recessive for Gene F is covered in a dense layer of hairs, giving it a soft appearance.
Gene P is related to the 'prickly' phenotype. A fruit fly that is homozygous recessive for Gene P is covered with sharp bristles, giving it a spiky texture.
Gene Y is analogous to the 'yucky' phenotype. A fruit fly that is homozygous recessive for Gene Y gives off an unpleasant odor and has a generally unappealing look.

Phenotype	Genotypes			Progeny Count
fuzzy, prickly, yucky	f	p	y	525
fuzzy, prickly	f	p	+	129
fuzzy, yucky	f	+	y	597
fuzzy	f	+	+	2,044
prickly, yucky	+	p	y	2,079
prickly	+	p	+	600
yucky	+	+	y	137
wildtype	+	+	+	539
TOTAL =				6,650

The resulting phenotypes are summarized in the table above.

The distance between genes F and P is 20 cM
The distance between genes F and Y is 34 cM
The distance between genes P and Y is 22 cM
The correct gene order determined from these distances is FPY

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes F and Y.

cc91_10af

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is analogous to the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene D is associated with the 'dewy' phenotype. A fruit fly that is homozygous recessive for Gene D appears moist, with its body covered in tiny droplets of water.
Gene T is affiliated with the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.

Phenotype	Genotypes			Progeny Count
artsy, dewy, tipsy	a	d	t	738
artsy, dewy	a	d	+	1,782
artsy, tipsy	a	+	t	86
artsy	a	+	+	345
dewy, tipsy	+	d	t	351
dewy	+	d	+	88
tipsy	+	+	t	1,698
wildtype	+	+	+	712
TOTAL =				5,800

The resulting phenotypes are summarized in the table above.

The distance between genes D and A is 15 cM
The distance between genes D and T is 37 cM
The distance between genes A and T is 28 cM
The correct gene order determined from these distances is DAT

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes D and T.

d75c_2477

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene E is affiliated with the 'eery' phenotype. A fruit fly that is homozygous recessive for Gene E appears to have something off, crooked limbs and other twisted appendages.
Gene J is linked with the 'jerky' phenotype. A fruit fly that is homozygous recessive for Gene J moves in rapid and sudden movements, displaying an unpredictable flight pattern.
Gene K is linked with the 'kidney' phenotype. A fruit fly that is homozygous recessive for Gene K has a body shape that is curved, similar to a kidney bean.

Phenotype	Genotypes			Progeny Count
eery, jerky, kidney	e	j	k	56
eery, jerky	e	j	+	589
eery, kidney	e	+	k	865
eery	e	+	+	2,681
jerky, kidney	+	j	k	2,608
jerky	+	j	+	816
kidney	+	+	k	518
wildtype	+	+	+	67
TOTAL =				8,200

The resulting phenotypes are summarized in the table above.

The distance between genes J and E is 15 cM
The distance between genes J and K is 34 cM
The distance between genes E and K is 22 cM
The correct gene order determined from these distances is JEK

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes J and K.

9188_23c4

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene A is correlated with the 'artsy' phenotype. A fruit fly that is homozygous recessive for Gene A has wings that are colorful and distinctive patterns.
Gene H is associated with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene R is linked with the 'rusty' phenotype. A fruit fly that is homozygous recessive for Gene R has a reddish-brown color, much like rusted iron metal.

Phenotype	Genotypes			Progeny Count
artsy, horsey, rusty	a	h	r	511
artsy, horsey	a	h	+	2,573
artsy, rusty	a	+	r	147
artsy	a	+	+	877
horsey, rusty	+	h	r	843
horsey	+	h	+	133
rusty	+	+	r	2,427
wildtype	+	+	+	489
TOTAL =				8,000

The resulting phenotypes are summarized in the table above.

The distance between genes H and A is 25 cM
The distance between genes H and R is 34 cM
The distance between genes A and R is 16 cM
The correct gene order determined from these distances is HAR

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes H and R.

b97d_2477

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene C is related to the 'chummy' phenotype. A fruit fly that is homozygous recessive for Gene C shows behavior where it always maintains a close distance to other flies.
Gene E is related to the 'eery' phenotype. A fruit fly that is homozygous recessive for Gene E appears to have something off, crooked limbs and other twisted appendages.
Gene K is correlated with the 'kidney' phenotype. A fruit fly that is homozygous recessive for Gene K has a body shape that is curved, similar to a kidney bean.

Phenotype	Genotypes			Progeny Count
chummy, eery, kidney	c	e	k	64
chummy, eery	c	e	+	950
chummy, kidney	c	+	k	2,828
chummy	c	+	+	602
eery, kidney	+	e	k	559
eery	+	e	+	2,719
kidney	+	+	k	813
wildtype	+	+	+	65
TOTAL =				8,600

The resulting phenotypes are summarized in the table above.

The distance between genes C and E is 22 cM
The distance between genes C and K is 34 cM
The distance between genes E and K is 15 cM
The correct gene order determined from these distances is CEK

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes C and K.

11aa_10af

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene H is associated with the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene K is connected with the 'kidney' phenotype. A fruit fly that is homozygous recessive for Gene K has a body shape that is curved, similar to a kidney bean.
Gene N is connected with the 'nerdy' phenotype. A fruit fly that is homozygous recessive for Gene N has large, prominent eyes that stand out, much like thick-rimmed glasses.

Phenotype	Genotypes			Progeny Count
horsey, kidney, nerdy	h	k	n	159
horsey, kidney	h	k	+	2,023
horsey, nerdy	h	+	n	704
horsey	h	+	+	562
kidney, nerdy	+	k	n	560
kidney	+	k	+	690
nerdy	+	+	n	1,955
wildtype	+	+	+	147
TOTAL =				6,800

The resulting phenotypes are summarized in the table above.

The distance between genes H and N is 25 cM
The distance between genes H and K is 37 cM
The distance between genes N and K is 21 cM
The correct gene order determined from these distances is HNK

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes H and K.

eace_40f0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene C is correlated with the 'chummy' phenotype. A fruit fly that is homozygous recessive for Gene C shows behavior where it always maintains a close distance to other flies.
Gene T is analogous to the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.
Gene X is linked with the 'xanthic' phenotype. A fruit fly that is homozygous recessive for Gene X has a fluorescent bright yellow coloring.

Phenotype	Genotypes			Progeny Count
chummy, tipsy, xanthic	c	t	x	86
chummy, tipsy	c	t	+	608
chummy, xanthic	c	+	x	12
chummy	c	+	+	213
tipsy, xanthic	+	t	x	224
tipsy	+	t	+	7
xanthic	+	+	x	665
wildtype	+	+	+	85
TOTAL =				1,900

The resulting phenotypes are summarized in the table above.

The distance between genes T and C is 24 cM
The distance between genes T and X is 32 cM
The distance between genes C and X is 10 cM
The correct gene order determined from these distances is TCX

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes T and X.

c93e_c5f9

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene H is analogous to the 'horsey' phenotype. A fruit fly that is homozygous recessive for Gene H is quite big and strong-looking, much larger than your typical fruit fly.
Gene K is correlated with the 'kidney' phenotype. A fruit fly that is homozygous recessive for Gene K has a body shape that is curved, similar to a kidney bean.
Gene T is related to the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.

Phenotype	Genotypes			Progeny Count
horsey, kidney, tipsy	h	k	t	1,109
horsey, kidney	h	k	+	167
horsey, tipsy	h	+	t	422
horsey	h	+	+	9
kidney, tipsy	+	k	t	8
kidney	+	k	+	411
tipsy	+	+	t	190
wildtype	+	+	+	1,084
TOTAL =				3,400

The resulting phenotypes are summarized in the table above.

The distance between genes K and H is 25 cM
The distance between genes K and T is 35 cM
The distance between genes H and T is 11 cM
The correct gene order determined from these distances is KHT

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes K and T.

7e59_baf0

Three-Point Test Cross Problem

A standard three-point test cross involves crossing a heterozygous organism for all three genes with an organism that is homozygous recessive for all three genes

For this problem, a test cross using a fruit fly (Drosophila melanogaster) heterozygous for three genes was conducted to understand their genetic interactions.

Characteristics of Recessive Phenotypes

Gene E is correlated with the 'eery' phenotype. A fruit fly that is homozygous recessive for Gene E appears to have something off, crooked limbs and other twisted appendages.
Gene N is affiliated with the 'nerdy' phenotype. A fruit fly that is homozygous recessive for Gene N has large, prominent eyes that stand out, much like thick-rimmed glasses.
Gene T is related to the 'tipsy' phenotype. A fruit fly that is homozygous recessive for Gene T moves in an erratic path, suggesting a lack of coordination, as if intoxicated.

Phenotype	Genotypes			Progeny Count
eery, nerdy, tipsy	e	n	t	340
eery, nerdy	e	n	+	915
eery, tipsy	e	+	t	93
eery	e	+	+	2,869
nerdy, tipsy	+	n	t	2,911
nerdy	+	n	+	77
tipsy	+	+	t	955
wildtype	+	+	+	340
TOTAL =				8,500

The resulting phenotypes are summarized in the table above.

The distance between genes E and T is 10 cM
The distance between genes E and N is 30 cM
The distance between genes T and N is 24 cM
The correct gene order determined from these distances is ETN

Step-by-Step Instructions for Calculating Interference

Step 1: Count the observed number of double crossovers from the data table.
Step 2: Calculate the probability of independent crossovers between distant genes.

Multiply the two individual crossover probabilities (based on their distance) for both adjacent gene pairs.

Step 3: Determine the expected number of double crossovers.

Multiply the combined probability (from Step 2) by the total progeny count.

Step 4: Calculate the Coefficient of Coincidence (CoC).

Divide the observed number of double crossovers (from Step 1) by the expected number (from Step 3).

Step 5: Calculate Interference.

Interference is given by the formula: Interference = 1 - CoC.

Question

Based on the traits expressed in the offspring, select the correct fraction that represents the interference level between genes E and N.