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 
Matching Chromosome Structure Alterations to Descriptions
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Match each of the following alterations to chromosome structure with their corresponding descriptions.
Note: Each choice will be used exactly once.
| Your Choice | Prompt | |
|---|---|---|
| 1. paracentric inversion | ||
| 2. reciprocal translocation | ||
| 3. Robertsonian translocation | ||
| 4. non-disjunction | ||
| 5. deletion |
Drag one of the choices below:
- A. segments from two different chromosomes have been exchanged
- B. entire chromosome has attached to another at the centromere
- C. a sequence of DNA is left out during DNA replication
- D. the failure of sister chromatids to separate properly during cell division
- E. a portion of a single chromosome arm has broken off, reversed, and reattached in its original place
Matching Chromosome Shapes to Descriptions
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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. Dicentric | ||
| 2. Submetacentric | ||
| 3. Metacentric | ||
| 4. Acentric | ||
| 5. Acrocentric |
Drag one of the choices below:
- A. the chromosome most resembles a perfect letter X during metaphase
- B. the centromere situated so that one arm is somewhat shorter than the other
- C. a chromosome with formed through the fusion of two chromosome segments, each with a centromere
- D. the centromere is located very close to one end of the chromosome
- E. an unstable chromosome with no centromere
Types of Chromosomal Alterations
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Which one of the following alterations to chromosome structure correspond to the description 'in humans, these alterations only occur with chromosomes 13, 14, 15, 21, and 22'.
Chromosome Shape Categories Based on Descriptions
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Which one of the following categories of chromosome shape correspond to the shape description 'an unstable chromosome lacking spindle fiber attachment'.
Chromosomal Abnormalities from Karyotype Notation
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Chromosome Band Proximity
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Cytogenetic Notations in Genetic Disorders
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Cytogenetic Notation for Rearrangements
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Chromosome Sub-Band Positions from Cytogenetic Notation
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Gene Order from Deletion Mutants (4 Genes, Random Labels)
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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.
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.
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 | |
|---|---|---|---|---|
| Del #1 | ||||
| Del #2 | ||||
| Del #3 |
There are four (4) genes, G, J, W, and Z, 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: G and Z
- Deletion #2: J, W, and Z
- Deletion #3: G, J, and Z
Requirement: 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.
Hint: The first gene at the start of the chromosome is Gene G.
Hint: The correct answer is a random sequence of four (4) letters.
What is the correct order of the four (4) genes?
Gene Order from Deletion Mutants (5 Genes, Random Labels)
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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, C, D, Q, X, and Y, 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, and Q
- Deletion #2: C and D
- Deletion #3: C, D, Q, and Y
- Deletion #4: D, Q, X, and Y
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 from Deletion Mutants (6 Genes, Random Labels)
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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.
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 | Gene 6 | |
|---|---|---|---|---|---|---|
| Del #1 | ||||||
| Del #2 | ||||||
| Del #3 | ||||||
| Del #4 | ||||||
| Del #5 |
There are six (6) genes, A, B, K, P, Q, and S, 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: B, P, Q, and S
- Deletion #2: B, K, P, Q, and S
- Deletion #3: A, K, P, Q, and S
- Deletion #4: B, P, and Q
- Deletion #5: A, K, Q, and S
Requirement: 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.
Hint: The correct answer is a random sequence of six (6) letters.
What is the correct order of the six (6) genes?
Gene Order from Deletion Mutants (4 Genes, Word Labels)
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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.
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.
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 | |
|---|---|---|---|---|
| Del #1 | ||||
| Del #2 | ||||
| Del #3 |
There are four (4) genes, A, E, S, and T, 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, S, and T
- Deletion #2: A, E, and T
- Deletion #3: A and E
Requirement: 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.
Hint: The first gene at the start of the chromosome is Gene E.
Hint: The correct answer is an English dictionary word of length four (4).
What is the correct order of the four (4) genes?
Gene Order from Deletion Mutants (5 Genes, Word Labels)
Click to show Gene Order from Deletion Mutants (5 Genes, Word Labels) 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, L, P, 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, and S
- Deletion #2: A, E, L, and S
- Deletion #3: E, L, and P
- Deletion #4: A, E, L, 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 from Deletion Mutants (6 Genes, Word Labels)
Click to show Gene Order from Deletion Mutants (6 Genes, Word Labels) 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.
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 | Gene 6 | |
|---|---|---|---|---|---|---|
| Del #1 | ||||||
| Del #2 | ||||||
| Del #3 | ||||||
| Del #4 |
There are six (6) genes, A, E, L, P, S, and T, 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: E, L, S, and T
- Deletion #2: E and S
- Deletion #3: A, E, L, and P
- Deletion #4: A, E, L, and S
Requirement: 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.
Hint: The correct answer is an English dictionary word of length six (6).
What is the correct order of the six (6) genes?
Chromosomal Translocation Outcomes (Color)
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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 ◀CDEFGHIJKLM▶ and ◀QRSTUVWX▶ undergo a reciprocal translocation after breaks between G⏐H and U⏐V, 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
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A a decaploid plant species is found to be 10n = 40 chromosomes.
How many chromosomes would present in the gametes of this species?
Note: 40/2 = 20 and 40/10 = 4
Monoploid and Haploid Numbers from Chromosome Counts
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A certain plant is found to be a dodecaploid (12n) with 96 chromosomes in total.
What are the monoploid (m) and haploid (h) numbers for this plant?
Note: 96/12 = 8 and 96/2 = 48
Gametes from Robertsonian Translocation
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An individual has a Robertsonian translocation involving chromosomes 14 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.
Balanced Translocation Segregation Outcomes
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A phenotypically wildtype prospective couple seeks genetic counseling. The man has a balanced translocation, between chromosomes 13 and 15.This means that a segment of chromosome 13 has been exchanged with a segment of chromosome 15 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: 13, 15
- Segregation Type: adjacent-2
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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 adjacent-2 segregation.
Your task is to select the two (2) gametes produced by adjacent-2 segregation.
CHECK TWO BOXES below!