Question

Translocation homozygotes lead to alteration in

• A. gene number
• B. linkage map
• C. sequence of genes
• D. linkage groups

Hint:

A linkage group represents a physical chromosome. Since translocation physically transfers chromosome segments to entirely different non-homologous chromosomes, it directly changes the composition of the linkage groups.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Translocation is a type of chromosomal rearrangement where a segment of one chromosome breaks off and attaches to a non-homologous chromosome.
A translocation homozygote carries the translocated chromosomes in both homologous pairs.

Step 2: Detailed Explanation:
Let us evaluate how chromosomal translocations affect genomic parameters:
- Gene number: Because translocation is a rearrangement (non-homologous exchange) and is homozygous, there is no gain or loss of genetic material, so the total gene number remains unchanged.
- Sequence of genes: The sequence of genes changes locally near the breakpoints, but the major structural change occurs at the chromosomal level.
- Linkage groups: A linkage group corresponds to a chromosome. Since translocation exchanges segments between non-homologous chromosomes, genes that were previously linked are now unlinked, and genes that were unlinked are now linked on a new chromosome. This significantly reorganizes and alters the linkage groups.

Step 3: Final Answer:
Therefore, translocation homozygotes primarily lead to an alteration in the linkage groups, matching Option (D).