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Questions and Answers
What are structural chromosome aberrations typically referred to as?
What are structural chromosome aberrations typically referred to as?
- Chromosomal alterations
- Chromosomal mutations (correct)
- Chromosomal inflections
- Genetic variations
Which of the following is NOT a primary way in which the structure of chromosomes can be altered?
Which of the following is NOT a primary way in which the structure of chromosomes can be altered?
- Evaporation (correct)
- Translocation
- Duplication
- Inversion
What is a result of structural chromosome rearrangements?
What is a result of structural chromosome rearrangements?
- Higher likelihood of obesity
- Increased risk of allergies
- Enhanced immune response
- Birth defects (correct)
Which alteration leads to an increase in the total amount of genetic information in chromosomes?
Which alteration leads to an increase in the total amount of genetic information in chromosomes?
What happens during a deletion in chromosome structure?
What happens during a deletion in chromosome structure?
What type of aberration retains the total genetic information but rearranges it?
What type of aberration retains the total genetic information but rearranges it?
Chromosomal aberrations can affect which of the following aspects?
Chromosomal aberrations can affect which of the following aspects?
What defines chromosomal aberrations according to structural changes?
What defines chromosomal aberrations according to structural changes?
Which of the following is an example of structural alteration in chromosomes?
Which of the following is an example of structural alteration in chromosomes?
How are chromosomal aberrations primarily categorized?
How are chromosomal aberrations primarily categorized?
What is the result of a deletion in a homozygous wild-type organism?
What is the result of a deletion in a homozygous wild-type organism?
What type of chromosome break leads to an acentric chromosome upon deletion of the centromere?
What type of chromosome break leads to an acentric chromosome upon deletion of the centromere?
How does a duplication typically occur during meiosis?
How does a duplication typically occur during meiosis?
Which agent is NOT mentioned as a cause of chromosome breakage?
Which agent is NOT mentioned as a cause of chromosome breakage?
What is a key consequence of deletion on the centromere?
What is a key consequence of deletion on the centromere?
What characterizes interstitial deletions?
What characterizes interstitial deletions?
Which of the following syndromes results from a deletion on chromosome 5?
Which of the following syndromes results from a deletion on chromosome 5?
What is the relationship between duplications and deletions during chromosome alteration?
What is the relationship between duplications and deletions during chromosome alteration?
What is the primary effect of the Bar allele in Drosophila?
What is the primary effect of the Bar allele in Drosophila?
What occurs when a chromosome segment reintegrates at 180° from its original orientation?
What occurs when a chromosome segment reintegrates at 180° from its original orientation?
In a heterozygote with an inversion, what happens if crossing-over occurs?
In a heterozygote with an inversion, what happens if crossing-over occurs?
What is a common result of imbalanced gametes produced from inversions?
What is a common result of imbalanced gametes produced from inversions?
What defines a simple translocation?
What defines a simple translocation?
Which statement about inversion loops in heterozygotes is accurate?
Which statement about inversion loops in heterozygotes is accurate?
Which type of translocation involves breakage in two non-homologous chromosomes?
Which type of translocation involves breakage in two non-homologous chromosomes?
What is the meiotic consequence of an inversion in a homozygote?
What is the meiotic consequence of an inversion in a homozygote?
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Study Notes
Chromosomal Aberration
- Chromosomal aberrations are changes that affect the structure or number of chromosomes.
- Structural changes in chromosomes can lead to birth defects, mental retardation, and infertility.
- Allelic variations are caused by mutations in specific genes.
Structural Changes
- The total amount of genetic information can change through duplication or deletion.
- Genetic material can be rearranged in the chromosome, without changing the total amount, through inversion or translocation.
Deletion
- A deficiency occurs when a portion of a chromosome is lost due to breakage.
- Breakages can be caused by radiation, chemicals, drugs, or viruses.
- A deletion may be terminal (at the end of a chromosome) or interstitial (in the middle of a chromosome).
- The effects of a deletion depend on the deleted genes.
- A deletion in one allele of a homozygous wild-type organism may not have an effect on the phenotype, while the same deletion in a heterozygote would produce a mutant phenotype.
- Deletion of the centromere results in an acentric chromosome that is lost, which can have serious consequences.
- Examples of human disorders caused by deletions include Cri-du-chat syndrome (deletion of part of chromosome 5).
Duplication
- Duplication involves the addition of one or more genes to a chromosome due to the attachment of a chromosomal fragment.
- Duplications often occur during unequal crossing over during meiosis, where homologous chromosomes are misaligned.
- Duplications generally do not produce significant phenotypic consequences.
- An example is the Bar allele in Drosophila eye shape, which reduces the number of eye facets.
Inversion
- Inversion occurs when a chromosome segment is excised and reintegrates in the opposite orientation.
- The effect of inversions in a heterozygote depends on whether crossing over occurs.
- If crossing over occurs in an inversion, unequal crossover can lead to serious genetic consequences.
Translocation
- Translocation involves the transfer of a chromosome segment to a different part of the same chromosome or to a different chromosome.
- Simple translocations involve the attachment of a terminal segment of a chromosome to another chromosome.
- Reciprocal translocations involve breakage in two non-homologous chromosomes, followed by the reunion of broken segments to the wrong partners.
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