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9: Chromosomal Disorders

Students interpret karyotypes, identify aneuploid conditions, classify chromosomal abnormalities, and predict outcomes of meiosis with translocations.

LibreTexts reference: Chapter 9: Chromosomal Disorders LibreTexts

Chromosome Shapes and Descriptions

Click to show Chromosome Shapes and Descriptions example problem

Match each of the following categories of chromosome shape with their corresponding shape descriptions.
Note: Each choice will be used exactly once.

Your Choice Prompt
Drop Your Choice Here 1. Dicentric
Drop Your Choice Here 2. Metacentric
Drop Your Choice Here 3. Acentric
Drop Your Choice Here 4. Submetacentric
Drop Your Choice Here 5. Acrocentric

Drag one of the choices below:

  • A. a chromosome with slightly shorter p arm relative to q arm
  • B. the centromere is located very close to one end of the chromosome
  • C. an unstable chromosome with no centromere
  • D. an abnormal chromosome with two centromeres that often appear in cancer cells
  • E. the chromosome most resembles a perfect letter X during metaphase
 

Chromosome Shapes from Centromere and Arm Lengths

Click to show Chromosome Shapes from Centromere and Arm Lengths example problem

Which one of the following categories of chromosome shape correspond to the shape description 'the centromere situated so that one arm is somewhat shorter than the other'.

 

Chromosomal Abnormalities from Karyotype Notation

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What does 45,X signify in a human karyotype?
 

Cytogenetic Notation for Aneuploidy

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In human genetics, what does the notation "47,+9,XX" indicate?
 

Chromosome Band Proximity

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For chromosome 6p, which band lies most distal (farthest from the centromere)?
 

Cytogenetic Notation for Rearrangements

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What does the notation "46,XX,t(10;8)(p11;q15)" describe in human karyotypes?
 

Cytogenetic Notation Karyotypes

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In cytogenetic notation, what does "47,XXY" refer to?
 

Gene Order Determination

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Using Deletion Mutants to Determine Gene Order

Deletion mutants are an essential tool in genetics for uncovering the order of five (5) genes on a chromosome. Deletions remove specific regions of the chromosome, allowing researchers to observe the effects of the missing genes on the phenotype of the organism. This approach is particularly useful for identifying the locations of recessive genes, which are only revealed when the corresponding wildtype copies are absent.
In a test cross involving deletion mutants, one parent carries a full-length wildtype chromosome and a second chromosome with a deletion, while the other parent is homozygous recessive for all five genes. Offspring inheriting the full-length wildtype chromosome display the dominant phenotype for all five genes in the test cross. However, offspring inheriting the chromosome with the deletion will display some recessive traits. These recessive traits uncover the missing genes in the deleted region. By analyzing which genes are uncovered in a series of different deletion mutants, the linear order of the genes can be determined.
In organisms such as Drosophila melanogaster, polytene chromosomes from the salivary glands provide a physical map for studying deletions. Polytene chromosomes are giant chromosomes with distinct banding patterns, allowing researchers to directly visualize which regions of the chromosome are deleted. This visual representation complements the genetic data obtained from test crosses.
For this problem, deletion mutants have been generated for a chromosome containing five genes. Your goal is to analyze the phenotypic data resulting from these deletions and determine the correct linear order of the genes.

Step-by-Step Instructions for Solving Deletion Mutant Problems
  • Step 1: Simplify the information.
    • List the genes and deletions provided in the question.
    • Organize the deletions in a clear table or list format for easier analysis.
  • Step 2: Create a template for the gene order.
    • Start with placeholders for each gene (e.g., _ _ _ _).
    • Insert known genes based on hints (e.g., the first or last gene).
  • Step 3: Identify deletions containing the first gene.
    • Analyze deletions that include the first gene to determine its neighbors.
    • Use deletions that overlap to narrow down adjacent genes.
  • Step 4: Analyze deletions containing the next genes.
    • Look for deletions that include specific pairs of genes.
    • Identify deletions that exclude certain genes to resolve ambiguities.
  • Step 5: Verify the answer using all of the listed deletions.
    • Deletion questions can be hard to solve, but once you have an answer, it is easy to check if it is correct!
    • Go through each deletion and confirm that the proposed gene order matches the genes included in that deletion.
    • If any deletion is inconsistent with the proposed order, your answer is wrong.
Gene 1 Gene 2 Gene 3 Gene 4 Gene 5
Del #1          
Del #2          
Del #3          
Del #4          

There are five (5) genes, A, H, K, Q, and X, closely linked in a single chromosome. However, their order is unknown. In the region, four (4) deletions have been identified. These deletions uncover recessive alleles of the genes as follows:

  • Deletion #1: A, H, K, and Q
  • Deletion #2: H, K, Q, and X
  • Deletion #3: A, K, and Q
  • Deletion #4: H, Q, and X

Requirement: Enter your answer in the blank using only five (5) letters, or one comma every three (3) letters. Do not include extra commas or spaces in your answer.
Hint: The correct answer is a random sequence of five (5) letters.
What is the correct order of the five (5) genes?

 

Gene Order Determination

Click to show Gene Order Determination example problem

Using Deletion Mutants to Determine Gene Order

Deletion mutants are an essential tool in genetics for uncovering the order of five (5) genes on a chromosome. Deletions remove specific regions of the chromosome, allowing researchers to observe the effects of the missing genes on the phenotype of the organism. This approach is particularly useful for identifying the locations of recessive genes, which are only revealed when the corresponding wildtype copies are absent.
In a test cross involving deletion mutants, one parent carries a full-length wildtype chromosome and a second chromosome with a deletion, while the other parent is homozygous recessive for all five genes. Offspring inheriting the full-length wildtype chromosome display the dominant phenotype for all five genes in the test cross. However, offspring inheriting the chromosome with the deletion will display some recessive traits. These recessive traits uncover the missing genes in the deleted region. By analyzing which genes are uncovered in a series of different deletion mutants, the linear order of the genes can be determined.
In organisms such as Drosophila melanogaster, polytene chromosomes from the salivary glands provide a physical map for studying deletions. Polytene chromosomes are giant chromosomes with distinct banding patterns, allowing researchers to directly visualize which regions of the chromosome are deleted. This visual representation complements the genetic data obtained from test crosses.
For this problem, deletion mutants have been generated for a chromosome containing five genes. Your goal is to analyze the phenotypic data resulting from these deletions and determine the correct linear order of the genes.

Step-by-Step Instructions for Solving Deletion Mutant Problems
  • Step 1: Simplify the information.
    • List the genes and deletions provided in the question.
    • Organize the deletions in a clear table or list format for easier analysis.
  • Step 2: Create a template for the gene order.
    • Start with placeholders for each gene (e.g., _ _ _ _).
    • Insert known genes based on hints (e.g., the first or last gene).
  • Step 3: Identify deletions containing the first gene.
    • Analyze deletions that include the first gene to determine its neighbors.
    • Use deletions that overlap to narrow down adjacent genes.
  • Step 4: Analyze deletions containing the next genes.
    • Look for deletions that include specific pairs of genes.
    • Identify deletions that exclude certain genes to resolve ambiguities.
  • Step 5: Verify the answer using all of the listed deletions.
    • Deletion questions can be hard to solve, but once you have an answer, it is easy to check if it is correct!
    • Go through each deletion and confirm that the proposed gene order matches the genes included in that deletion.
    • If any deletion is inconsistent with the proposed order, your answer is wrong.
Gene 1 Gene 2 Gene 3 Gene 4 Gene 5
Del #1          
Del #2          
Del #3          
Del #4          

There are five (5) genes, A, E, P, R, and S, closely linked in a single chromosome. However, their order is unknown. In the region, four (4) deletions have been identified. These deletions uncover recessive alleles of the genes as follows:

  • Deletion #1: A, E, P, and R
  • Deletion #2: A, E, R, and S
  • Deletion #3: A and R
  • Deletion #4: A, E, and P

Requirement: Enter your answer in the blank using only five (5) letters, or one comma every three (3) letters. Do not include extra commas or spaces in your answer.
Hint: The correct answer is an English dictionary word of length five (5).
What is the correct order of the five (5) genes?

 

Gene Order with Deletion Mutants (4 Genes, Free Response)

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Using Deletion Mutants to Determine Gene Order

Deletion mutants are an essential tool in genetics for uncovering the order of four (4) genes on a chromosome. Deletions remove specific regions of the chromosome, allowing researchers to observe the effects of the missing genes on the phenotype of the organism. This approach is particularly useful for identifying the locations of recessive genes, which are only revealed when the corresponding wildtype copies are absent.
In a test cross involving deletion mutants, one parent carries a full-length wildtype chromosome and a second chromosome with a deletion, while the other parent is homozygous recessive for all four genes. Offspring inheriting the full-length wildtype chromosome display the dominant phenotype for all four genes in the test cross. However, offspring inheriting the chromosome with the deletion will display some recessive traits. These recessive traits uncover the missing genes in the deleted region. By analyzing which genes are uncovered in a series of different deletion mutants, the linear order of the genes can be determined.
For this problem, deletion mutants have been generated for a chromosome containing four genes. Your goal is to analyze the phenotypic data resulting from these deletions and determine the correct linear order of the genes.
There are four (4) genes, C, E, F, and W, closely linked in a single chromosome. However, their order is unknown. In the region, three (3) deletions have been identified. These deletions uncover recessive alleles of the genes as follows:

  • Deletion #1: E and W
  • Deletion #2: E, F, and W
  • Deletion #3: C, F, and W

What is the correct order of the four (4) genes?
Hint 1: The first gene at start of the chromosome is gene C.
Hint 2: Enter your answer in the blank using only four (4) letters, or one comma every three (3) letters. Do not include extra commas or spaces in your answer.

Step-by-Step Instructions for Solving Deletion Mutant Problems
  • Step 1: Simplify the information.
    • List the genes and deletions provided in the question.
    • Organize the deletions in a clear table or list format for easier analysis.
  • Step 2: Create a template for the gene order.
    • Start with placeholders for each gene (e.g., _ _ _ _).
    • Insert known genes based on hints (e.g., the first or last gene).
  • Step 3: Identify deletions containing the first gene.
    • Analyze deletions that include the first gene to determine its neighbors.
    • Use deletions that overlap to narrow down adjacent genes.
  • Step 4: Analyze deletions containing the next genes.
    • Look for deletions that include specific pairs of genes.
    • Identify deletions that exclude certain genes to resolve ambiguities.
  • Step 5: Verify the answer using all of the listed deletions.
    • Deletion questions can be hard to solve, but once you have an answer, it is easy to check if it is correct!
    • Go through each deletion and confirm that the proposed gene order matches the genes included in that deletion.
    • If any deletion is inconsistent with the proposed order, your answer is wrong.
 

Gene Order with Deletion Mutants (4 Genes, Table)

Click to show Gene Order with Deletion Mutants (4 Genes, Table) example problem

Using Deletion Mutants to Determine Gene Order

Deletion mutants are an essential tool in genetics for uncovering the order of four (4) genes on a chromosome. Deletions remove specific regions of the chromosome, allowing researchers to observe the effects of the missing genes on the phenotype of the organism. This approach is particularly useful for identifying the locations of recessive genes, which are only revealed when the corresponding wildtype copies are absent.
In a test cross involving deletion mutants, one parent carries a full-length wildtype chromosome and a second chromosome with a deletion, while the other parent is homozygous recessive for all four genes. Offspring inheriting the full-length wildtype chromosome display the dominant phenotype for all four genes in the test cross. However, offspring inheriting the chromosome with the deletion will display some recessive traits. These recessive traits uncover the missing genes in the deleted region. By analyzing which genes are uncovered in a series of different deletion mutants, the linear order of the genes can be determined.
In organisms such as Drosophila melanogaster, polytene chromosomes from the salivary glands provide a physical map for studying deletions. Polytene chromosomes are giant chromosomes with distinct banding patterns, allowing researchers to directly visualize which regions of the chromosome are deleted. This visual representation complements the genetic data obtained from test crosses.
For this problem, deletion mutants have been generated for a chromosome containing four genes. Your goal is to analyze the phenotypic data resulting from these deletions and determine the correct linear order of the genes.

Gene 1 Gene 2 Gene 3 Gene 4
Del #1
Del #2
Del #3

There are four (4) genes, D, E, H, and J, closely linked in a single chromosome. However, their order is unknown. In the region, three (3) deletions have been identified. These deletions uncover recessive alleles of the genes as follows:

  • Deletion #1: H and J
  • Deletion #2: D, E, and H
  • Deletion #3: D, H, and J

What is the correct order of the four (4) genes?
Hint 1: The first gene at start of the chromosome is gene E.
Hint 2: Enter your answer in the blank using only four (4) letters, or one comma every three (3) letters. Do not include extra commas or spaces in your answer.

Step-by-Step Instructions for Solving Deletion Mutant Problems
  • Step 1: Simplify the information.
    • List the genes and deletions provided in the question.
    • Organize the deletions in a clear table or list format for easier analysis.
  • Step 2: Create a template for the gene order.
    • Start with placeholders for each gene (e.g., _ _ _ _).
    • Insert known genes based on hints (e.g., the first or last gene).
  • Step 3: Identify deletions containing the first gene.
    • Analyze deletions that include the first gene to determine its neighbors.
    • Use deletions that overlap to narrow down adjacent genes.
  • Step 4: Analyze deletions containing the next genes.
    • Look for deletions that include specific pairs of genes.
    • Identify deletions that exclude certain genes to resolve ambiguities.
  • Step 5: Verify the answer using all of the listed deletions.
    • Deletion questions can be hard to solve, but once you have an answer, it is easy to check if it is correct!
    • Go through each deletion and confirm that the proposed gene order matches the genes included in that deletion.
    • If any deletion is inconsistent with the proposed order, your answer is wrong.
 

Gene Order with Deletion Mutants (6 Genes, Table)

Click to show Gene Order with Deletion Mutants (6 Genes, Table) example problem

Using Deletion Mutants to Determine Gene Order

Deletion mutants are an essential tool in genetics for uncovering the order of six (6) genes on a chromosome. Deletions remove specific regions of the chromosome, allowing researchers to observe the effects of the missing genes on the phenotype of the organism. This approach is particularly useful for identifying the locations of recessive genes, which are only revealed when the corresponding wildtype copies are absent.
In a test cross involving deletion mutants, one parent carries a full-length wildtype chromosome and a second chromosome with a deletion, while the other parent is homozygous recessive for all six genes. Offspring inheriting the full-length wildtype chromosome display the dominant phenotype for all six genes in the test cross. However, offspring inheriting the chromosome with the deletion will display some recessive traits. These recessive traits uncover the missing genes in the deleted region. By analyzing which genes are uncovered in a series of different deletion mutants, the linear order of the genes can be determined.
In organisms such as Drosophila melanogaster, polytene chromosomes from the salivary glands provide a physical map for studying deletions. Polytene chromosomes are giant chromosomes with distinct banding patterns, allowing researchers to directly visualize which regions of the chromosome are deleted. This visual representation complements the genetic data obtained from test crosses.
For this problem, deletion mutants have been generated for a chromosome containing six genes. Your goal is to analyze the phenotypic data resulting from these deletions and determine the correct linear order of the genes.

Gene 1 Gene 2 Gene 3 Gene 4 Gene 5 Gene 6
Del #1
Del #2
Del #3
Del #4

There are six (6) genes, C, D, K, Q, R, and X, closely linked in a single chromosome. However, their order is unknown. In the region, four (4) deletions have been identified. These deletions uncover recessive alleles of the genes as follows:

  • Deletion #1: C, D, K, and X
  • Deletion #2: C, K, Q, R, and X
  • Deletion #3: C, K, and Q
  • Deletion #4: C, Q, and R

What is the correct order of the six (6) genes?
Hint 1: The first gene at start of the chromosome is gene D.
Hint 2: Enter your answer in the blank using only six (6) letters, or one comma every three (3) letters. Do not include extra commas or spaces in your answer.

Step-by-Step Instructions for Solving Deletion Mutant Problems
  • Step 1: Simplify the information.
    • List the genes and deletions provided in the question.
    • Organize the deletions in a clear table or list format for easier analysis.
  • Step 2: Create a template for the gene order.
    • Start with placeholders for each gene (e.g., _ _ _ _).
    • Insert known genes based on hints (e.g., the first or last gene).
  • Step 3: Identify deletions containing the first gene.
    • Analyze deletions that include the first gene to determine its neighbors.
    • Use deletions that overlap to narrow down adjacent genes.
  • Step 4: Analyze deletions containing the next genes.
    • Look for deletions that include specific pairs of genes.
    • Identify deletions that exclude certain genes to resolve ambiguities.
  • Step 5: Verify the answer using all of the listed deletions.
    • Deletion questions can be hard to solve, but once you have an answer, it is easy to check if it is correct!
    • Go through each deletion and confirm that the proposed gene order matches the genes included in that deletion.
    • If any deletion is inconsistent with the proposed order, your answer is wrong.
 

Gene Order with Deletion Mutants (8 Genes, Table)

Click to show Gene Order with Deletion Mutants (8 Genes, Table) example problem

Using Deletion Mutants to Determine Gene Order

Deletion mutants are an essential tool in genetics for uncovering the order of eight (8) genes on a chromosome. Deletions remove specific regions of the chromosome, allowing researchers to observe the effects of the missing genes on the phenotype of the organism. This approach is particularly useful for identifying the locations of recessive genes, which are only revealed when the corresponding wildtype copies are absent.
In a test cross involving deletion mutants, one parent carries a full-length wildtype chromosome and a second chromosome with a deletion, while the other parent is homozygous recessive for all eight genes. Offspring inheriting the full-length wildtype chromosome display the dominant phenotype for all eight genes in the test cross. However, offspring inheriting the chromosome with the deletion will display some recessive traits. These recessive traits uncover the missing genes in the deleted region. By analyzing which genes are uncovered in a series of different deletion mutants, the linear order of the genes can be determined.
In organisms such as Drosophila melanogaster, polytene chromosomes from the salivary glands provide a physical map for studying deletions. Polytene chromosomes are giant chromosomes with distinct banding patterns, allowing researchers to directly visualize which regions of the chromosome are deleted. This visual representation complements the genetic data obtained from test crosses.
For this problem, deletion mutants have been generated for a chromosome containing eight genes. Your goal is to analyze the phenotypic data resulting from these deletions and determine the correct linear order of the genes.

Gene 1 Gene 2 Gene 3 Gene 4 Gene 5 Gene 6 Gene 7 Gene 8
Del #1
Del #2
Del #3
Del #4
Del #5
Del #6

There are eight (8) genes, F, G, J, K, M, R, W, and X, closely linked in a single chromosome. However, their order is unknown. In the region, six (6) deletions have been identified. These deletions uncover recessive alleles of the genes as follows:

  • Deletion #1: F, J, K, M, and X
  • Deletion #2: F, J, K, and M
  • Deletion #3: F, G, K, W, and X
  • Deletion #4: G, K, W, and X
  • Deletion #5: F, J, K, W, and X
  • Deletion #6: F, J, K, M, and R

What is the correct order of the eight (8) genes?
Hint 1: The first gene at start of the chromosome is gene G.
Hint 2: Enter your answer in the blank using only eight (8) letters, or one comma every three (3) letters. Do not include extra commas or spaces in your answer.

Step-by-Step Instructions for Solving Deletion Mutant Problems
  • Step 1: Simplify the information.
    • List the genes and deletions provided in the question.
    • Organize the deletions in a clear table or list format for easier analysis.
  • Step 2: Create a template for the gene order.
    • Start with placeholders for each gene (e.g., _ _ _ _).
    • Insert known genes based on hints (e.g., the first or last gene).
  • Step 3: Identify deletions containing the first gene.
    • Analyze deletions that include the first gene to determine its neighbors.
    • Use deletions that overlap to narrow down adjacent genes.
  • Step 4: Analyze deletions containing the next genes.
    • Look for deletions that include specific pairs of genes.
    • Identify deletions that exclude certain genes to resolve ambiguities.
  • Step 5: Verify the answer using all of the listed deletions.
    • Deletion questions can be hard to solve, but once you have an answer, it is easy to check if it is correct!
    • Go through each deletion and confirm that the proposed gene order matches the genes included in that deletion.
    • If any deletion is inconsistent with the proposed order, your answer is wrong.
 

Gene Order with Deletion Mutants (16 Genes, Table)

Click to show Gene Order with Deletion Mutants (16 Genes, Table) example problem

Using Deletion Mutants to Determine Gene Order

Deletion mutants are an essential tool in genetics for uncovering the order of sixteen (16) genes on a chromosome. Deletions remove specific regions of the chromosome, allowing researchers to observe the effects of the missing genes on the phenotype of the organism. This approach is particularly useful for identifying the locations of recessive genes, which are only revealed when the corresponding wildtype copies are absent.
In a test cross involving deletion mutants, one parent carries a full-length wildtype chromosome and a second chromosome with a deletion, while the other parent is homozygous recessive for all sixteen genes. Offspring inheriting the full-length wildtype chromosome display the dominant phenotype for all sixteen genes in the test cross. However, offspring inheriting the chromosome with the deletion will display some recessive traits. These recessive traits uncover the missing genes in the deleted region. By analyzing which genes are uncovered in a series of different deletion mutants, the linear order of the genes can be determined.
In organisms such as Drosophila melanogaster, polytene chromosomes from the salivary glands provide a physical map for studying deletions. Polytene chromosomes are giant chromosomes with distinct banding patterns, allowing researchers to directly visualize which regions of the chromosome are deleted. This visual representation complements the genetic data obtained from test crosses.
For this problem, deletion mutants have been generated for a chromosome containing sixteen genes. Your goal is to analyze the phenotypic data resulting from these deletions and determine the correct linear order of the genes.

Gene 1 Gene 2 Gene 3 Gene 4 Gene 5 Gene 6 Gene 7 Gene 8 Gene 9 Gene 10 Gene 11 Gene 12 Gene 13 Gene 14 Gene 15 Gene 16
Del #1
Del #2
Del #3
Del #4
Del #5
Del #6
Del #7
Del #8
Del #9
Del #10
Del #11
Del #12

There are sixteen (16) genes, A, B, C, D, G, H, J, K, M, P, Q, R, S, T, W, and Z, closely linked in a single chromosome. However, their order is unknown. In the region, twelve (12) deletions have been identified. These deletions uncover recessive alleles of the genes as follows:

  • Deletion #1: A, B, G, H, J, Q, R, T, and Z
  • Deletion #2: A, B, G, and Q
  • Deletion #3: B, C, G, H, J, Q, R, T, and Z
  • Deletion #4: A, B, and M
  • Deletion #5: C, D, R, and Z
  • Deletion #6: A, B, M, and S
  • Deletion #7: K, P, S, and W
  • Deletion #8: S and W
  • Deletion #9: H, J, R, and T
  • Deletion #10: G, H, J, and Q
  • Deletion #11: C, G, H, J, R, T, and Z
  • Deletion #12: A, B, G, J, M, P, Q, S, and W

What is the correct order of the sixteen (16) genes?
Hint 1: The first gene at start of the chromosome is gene D.
Hint 2: Enter your answer in the blank using only sixteen (16) letters, or one comma every three (3) letters. Do not include extra commas or spaces in your answer.

Step-by-Step Instructions for Solving Deletion Mutant Problems
  • Step 1: Simplify the information.
    • List the genes and deletions provided in the question.
    • Organize the deletions in a clear table or list format for easier analysis.
  • Step 2: Create a template for the gene order.
    • Start with placeholders for each gene (e.g., _ _ _ _).
    • Insert known genes based on hints (e.g., the first or last gene).
  • Step 3: Identify deletions containing the first gene.
    • Analyze deletions that include the first gene to determine its neighbors.
    • Use deletions that overlap to narrow down adjacent genes.
  • Step 4: Analyze deletions containing the next genes.
    • Look for deletions that include specific pairs of genes.
    • Identify deletions that exclude certain genes to resolve ambiguities.
  • Step 5: Verify the answer using all of the listed deletions.
    • Deletion questions can be hard to solve, but once you have an answer, it is easy to check if it is correct!
    • Go through each deletion and confirm that the proposed gene order matches the genes included in that deletion.
    • If any deletion is inconsistent with the proposed order, your answer is wrong.
 

Chromosomal Translocation Outcomes (Black)

Click to show Chromosomal Translocation Outcomes (Black) example problem

In a reciprocal translocation, two nonhomologous chromosomes each break once and exchange their terminal fragments. Gene order within each fragment is preserved; only the junctions change.
Two chromosomes with the gene sequences ◀EFGHIJKL▶ and ◀PQRSTUVWX▶ undergo a reciprocal translocation after breaks between H⏐I and R⏐S, where the symbols: ◀ and ▶ represent the telomeres.
Which one of the following is NOT a possible product of this translocation?

 

Chromosomal Translocation Outcomes (Color)

Click to show Chromosomal Translocation Outcomes (Color) example problem

In a reciprocal translocation, two nonhomologous chromosomes each break once and exchange their terminal fragments. Gene order within each fragment is preserved; only the junctions change.
Two chromosomes with the gene sequences ◀BCDEFGHIJ▶ and ◀QRSTUVWXY▶ undergo a reciprocal translocation after breaks between E⏐F and T⏐U, where the symbols: ◀ and ▶ represent the telomeres.
Which one of the following is NOT a possible product of this translocation?

 

Gamete Chromosome Numbers in Polyploids

Click to show Gamete Chromosome Numbers in Polyploids example problem

A a hexaploid plant species is found to be 6n = 42 chromosomes.

How many chromosomes would present in the gametes of this species?

Note: 42/2 = 21 and 42/6 = 7

 

Monoploid and Haploid Numbers from Chromosome Counts

Click to show Monoploid and Haploid Numbers from Chromosome Counts example problem

A certain plant is found to be a tetradecaploid (14n) with 112 chromosomes in total.

What are the monoploid (m) and haploid (h) numbers for this plant?

Note: 112/14 = 8 and 112/2 = 56

 

Gametes from Robertsonian Translocation

Click to show Gametes from Robertsonian Translocation example problem

An individual has a Robertsonian translocation involving chromosomes 13 and 15.

Which one of the following gametes was formed by alternate segregation in this individual?
13p 13q
15p 15q
13q 15q

all of three of the chromosomes in a somatic cell are shown above.

 

Balanced Translocation Segregation Outcomes

Click to show Balanced Translocation Segregation Outcomes example problem

A phenotypically wildtype prospective couple seeks genetic counseling. The man has a balanced translocation, between chromosomes 18 and 22.This means that a segment of chromosome 18 has been exchanged with a segment of chromosome 22 without any gain or loss of genetic material. While balanced translocations typically do not affect the individual's phenotype, they can result in different types of gametes during reproduction.

  • Chromosome Pair: 18, 22
  • Segregation Type: adjacent-2
18
22
18
22

all four of the chromosomes present in a somatic cell are shown above

Below are all the possible gametes produced by the man with the translocation.
Among the six choices below, only two (2) gametes or two (2) sets of chromosomes are formed by adjacent-2 segregation.
Your task is to select the two (2) gametes produced by adjacent-2 segregation.
CHECK TWO BOXES below!

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