9: Chromosomal Disorders
Karyotypes, aneuploidy, rearrangements, deletions, translocations, and polyploidy.
Match Chromosome Shapes
Click to show Match Chromosome Shapes 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 | |
|---|---|---|
| 1. Metacentric | ||
| 2. Dicentric | ||
| 3. Submetacentric | ||
| 4. Acentric | ||
| 5. Acrocentric |
Drag one of the choices below:
- A. an unstable chromosome due to unpredictable spindle fiber attachment
- B. the centromere is very offset from the center leading to a very short arm
- C. the centromere situated so that one arm is somewhat shorter than the other
- D. the chromosome most resembles the letter V after anaphase separation
- E. an abnormal chromosome that lacks a centromere
Identify Chromosome Shapes from Centromere and Arm Length
Click to show Identify Chromosome Shapes from Centromere and Arm Length example problem
Which one of the following categories of chromosome shape correspond to the shape description 'a chromosome with slightly shorter p arm relative to q arm'.
Interpret Cytogenetic Notation for Aneuploidy
Click to show Interpret Cytogenetic Notation for Aneuploidy example problem
Interpret Cytogenetic Notation for Rearrangements
Click to show Interpret Cytogenetic Notation for Rearrangements example problem
Map Gene Order with Deletion Mutants (4 Genes, Free Response)
Click to show Map Gene Order with Deletion Mutants (4 Genes, Free Response) 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.
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, A, P, R, and S, 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: A, P, and S
- Deletion #2: A, P, and R
- Deletion #3: A and S
What is the correct order of the four (4) genes?
Hint 1: The first gene at start of the chromosome is gene R.
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.
Map Gene Order with Deletion Mutants (4 Genes, Table)
Click to show Map 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, B, K, M, and R, 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: B and K
- Deletion #2: B, K, and M
- Deletion #3: K, M, and R
What is the correct order of the four (4) genes?
Hint 1: The first gene at start of the chromosome is gene B.
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.
Map Gene Order with Deletion Mutants (6 Genes, Table)
Click to show Map 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 | ||||||
| Del #5 |
There are six (6) genes, E, K, M, R, T, and X, closely linked in a single chromosome. However, their order is unknown. In the region, five (5) deletions have been identified. These deletions uncover recessive alleles of the genes as follows:
- Deletion #1: M, R, and T
- Deletion #2: E, K, M, R, and X
- Deletion #3: E, M, R, and T
- Deletion #4: E, K, M, and R
- Deletion #5: E and R
What is the correct order of the six (6) genes?
Hint 1: The first gene at start of the chromosome is gene T.
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.
Map Gene Order with Deletion Mutants (8 Genes, Table)
Click to show Map 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, C, E, H, J, Q, S, T, and W, 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: C, E, J, and T
- Deletion #2: C, H, J, and T
- Deletion #3: H, Q, S, and W
- Deletion #4: C, H, Q, and T
- Deletion #5: C, H, Q, and S
- Deletion #6: C, H, J, Q, S, and T
What is the correct order of the eight (8) genes?
Hint 1: The first gene at start of the chromosome is gene E.
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.
Map Gene Order with Deletion Mutants (16 Genes, Table)
Click to show Map 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 | ||||||||||||||||
| Del #13 |
There are sixteen (16) genes, A, C, D, E, F, G, H, K, Q, R, S, T, W, X, Y, and Z, closely linked in a single chromosome. However, their order is unknown. In the region, thirteen (13) deletions have been identified. These deletions uncover recessive alleles of the genes as follows:
- Deletion #1: A, C, D, E, K, Q, T, W, and Z
- Deletion #2: A, C, E, Q, T, W, and Z
- Deletion #3: C, D, F, K, and W
- Deletion #4: G, H, S, and X
- Deletion #5: A, E, Q, T, and Y
- Deletion #6: C, K, Q, W, and Z
- Deletion #7: A, E, R, T, X, and Y
- Deletion #8: A, E, G, H, Q, R, T, X, and Y
- Deletion #9: A, E, H, Q, R, T, X, Y, and Z
- Deletion #10: C, K, and W
- Deletion #11: A, E, G, H, R, X, and Y
- Deletion #12: E, Q, T, W, and Z
- Deletion #13: A, E, Q, R, T, W, Y, and Z
What is the correct order of the sixteen (16) genes?
Hint 1: The first gene at start of the chromosome is gene F.
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.
Identify Chromosomal Translocation Outcomes (Black)
Click to show Identify 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?
Identify Chromosomal Translocation Outcomes (Color)
Click to show Identify 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 ◀CDEFGHIJK▶ and ◀MOPQRSTUVW▶ undergo a reciprocal translocation after breaks between G⏐H and P⏐Q, where the symbols: ◀ and ▶ represent the telomeres.
Which one of the following is NOT a possible product of this translocation?
Determine Gamete Chromosome Numbers in Polyploids
Click to show Determine Gamete Chromosome Numbers in Polyploids example problem
A a tetradecaploid plant species is found to be 14n = 140 chromosomes.
How many chromosomes would present in the gametes of this species?
Note: 140/2 = 70 and 140/14 = 10
Determine Monoploid and Haploid Numbers from Chromosome Counts
Click to show Determine Monoploid and Haploid Numbers from Chromosome Counts example problem
A certain plant is found to be a hexadecaploid (16n) with 80 chromosomes in total.
What are the monoploid (m) and haploid (h) numbers for this plant?
Note: 80/16 = 5 and 80/2 = 40
Predict Gametes from Robertsonian Translocation
Click to show Predict Gametes from Robertsonian Translocation example problem
An individual has a Robertsonian translocation involving chromosomes 13 and 21.
Which one of the following gametes was formed by alternate segregation in this individual?
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all of three of the chromosomes in a somatic cell are shown above.
Predict Balanced Translocation Segregation Outcomes
Click to show Predict Balanced Translocation Segregation Outcomes example problem
A phenotypically wildtype prospective couple seeks genetic counseling. The man has a balanced translocation, between chromosomes 2 and 4.This means that a segment of chromosome 2 has been exchanged with a segment of chromosome 4 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: 2, 4
- Segregation Type: alternate
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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 alternate segregation.
Your task is to select the two (2) gametes produced by alternate segregation.
CHECK TWO BOXES below!