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Questions and Answers
What are structural chromosome aberrations primarily responsible for?
What are structural chromosome aberrations primarily responsible for?
Which type of chromosome structural alteration is characterized by the removal of a gene segment?
Which type of chromosome structural alteration is characterized by the removal of a gene segment?
How are chromosomal aberrations categorized?
How are chromosomal aberrations categorized?
What can cause chromosomal breakage leading to structural aberrations?
What can cause chromosomal breakage leading to structural aberrations?
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What does the term 'inversion' refer to in chromosome structure alterations?
What does the term 'inversion' refer to in chromosome structure alterations?
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What is the outcome of translocation in chromosomes?
What is the outcome of translocation in chromosomes?
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What distinguishes terminal deletion from interstitial deletion?
What distinguishes terminal deletion from interstitial deletion?
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Which individual made significant contributions to the understanding of chromosomal aberrations, particularly duplications, deletions, and translocations?
Which individual made significant contributions to the understanding of chromosomal aberrations, particularly duplications, deletions, and translocations?
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What is the consequence of a deletion in a heterozygote organism?
What is the consequence of a deletion in a heterozygote organism?
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What typically results from the deletion of a centromere?
What typically results from the deletion of a centromere?
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What is a primary cause of chromosome duplications?
What is a primary cause of chromosome duplications?
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How do duplications typically affect an organism?
How do duplications typically affect an organism?
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What happens if crossing-over occurs in a heterozygote with an inversion?
What happens if crossing-over occurs in a heterozygote with an inversion?
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What do duplication loops in chromosomes allow during meiosis?
What do duplication loops in chromosomes allow during meiosis?
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What effect does a large chromosomal deletion have on a human organism?
What effect does a large chromosomal deletion have on a human organism?
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What occurs in a homozygote during meiosis when an inversion is present?
What occurs in a homozygote during meiosis when an inversion is present?
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Study Notes
Introduction
- Chromosomal aberrations are changes in the structure of chromosomes which can lead to birth defects, mental retardation, and infertility.
- Allelic variations are mutations in genes which can affect an individual, while chromosomal aberrations affect multiple genes.
- Chromosomal aberrations are also known as chromosomal mutations.
Alterations in Chromosome Structure
- Duplication: The amount of genetic information within a chromosome increases.
- Deletions: The amount of genetic information within a chromosome decreases.
- Inversion: The arrangement of genetic information within a chromosome changes, but the overall amount remains the same.
- Translocation: Genetic information from one chromosome moves to a non-homologous chromosome.
History
- 1926: A.H. Sturtevant discovered inversions in chromosomes.
- 1923: C.B. Bridges discovered duplications, deletions, and translocations in chromosomes.
Deletion
- Deletion is the loss of a portion of a chromosome, resulting in the loss of genes.
- Deletions can occur due to breaks in the chromosome caused by radiation, chemicals, drugs, or viruses.
- Terminal deletion: a single break near the end of a chromosome.
- Interstitial deletion: two breaks in the middle of a chromosome.
- Deletion of the centromere: results in an acentric chromosome which is lost, often leading to serious or lethal consequences.
- Examples of human disorders caused by large chromosomal deletions:
- Cri-du-chat syndrome - Deletion of part of the short arm of chromosome 5
Duplication
- Duplication is the addition of a chromosomal fragment, resulting in an increase in the number of genes.
- Duplications occur when there is an unequal exchange of genetic material during meiosis.
- Some duplications do not have significant phenotypic consequences, while others can lead to developmental abnormalities.
- Duplication loops can be observed during meiosis in organisms with duplication heterozygotes.
Inversion
- Inversion is the reversal of a chromosome segment.
- Paracentric inversion does not include the centromere.
- Pericentric inversion includes the centromere.
- Inversion can affect gene expression and lead to meiotic complications.
Translocation
- Translocation is the movement of genetic material from one chromosome to another.
- Reciprocal translocation is the exchange of segments between two non-homologous chromosomes.
- Non-reciprocal translocation is the movement of a segment of one chromosome to a different chromosome.
- Translocations can alter gene expression and can lead to infertility.
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Description
Explore the various types of chromosomal aberrations and their significance in genetics. This quiz covers key concepts such as duplications, deletions, inversions, and translocations. Additionally, it highlights historical milestones in the study of chromosomes.
