Ch. 8 - Chromosome Mutations: Variation in Number and Arrangement

Klug - Concepts of Genetics 12th Edition

Klug12th EditionConcepts of GeneticsISBN: 9780135564776당신이 사용하는 게 아니라요?교과서 변경

Klug 12th Edition

Ch. 8 - Chromosome Mutations: Variation in Number and Arrangement

문제 10

8장, 문제 10

Inversions are said to 'suppress crossing over.' Is this terminology technically correct? If not, restate the description accurately.

검증된 단계별 안내

Understand the concept of chromosomal inversions: an inversion is a chromosome rearrangement in which a segment of a chromosome is reversed end to end.

Recall that crossing over refers to the exchange of genetic material between homologous chromosomes during meiosis, which increases genetic diversity.

Recognize that inversions do not prevent the physical process of crossing over from occurring; rather, they affect the outcome of crossing over within the inverted segment.

Learn that crossing over within an inversion loop can produce abnormal chromatids (e.g., duplications or deletions), which are often inviable or selected against, leading to a reduction in viable recombinant offspring.

Therefore, the term 'suppress crossing over' is technically inaccurate; a more precise description is that inversions 'reduce the recovery of recombinant chromatids' or 'reduce the viability of crossover products' within the inverted region.

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주요 개념

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Chromosomal Inversions

Chromosomal inversions occur when a segment of a chromosome breaks off, flips, and reinserts in the reverse orientation. This rearrangement can affect gene order and pairing during meiosis, potentially leading to altered genetic outcomes.

Crossing Over During Meiosis

Crossing over is the exchange of genetic material between homologous chromosomes during prophase I of meiosis. It increases genetic diversity by producing new allele combinations but requires proper alignment of homologous regions.

Effect of Inversions on Recombination

Inversions do not completely prevent crossing over but suppress viable recombinant products because crossover within the inverted region can produce unbalanced or inviable gametes. Thus, the term 'suppress crossing over' is better described as 'suppress recovery of recombinant chromatids.'

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