Question

Which of the following statements is not true for two genes, that show 50 % recombination frequency?

• A. The genes are tightly linked.
• B. The genes show independent assortment.
• C. If the genes are present on the same chromosome, they undergo more than one crossover in every meiosis.
• D. The genes may be on different chromosomes.

Answer 1

The correct option is A The genes are tightly linked.

Recombination is the process of creating new arrangements of genes, either by crossing over or by independent segregation of homologous pairs of chromosomes. Cross over is the process of exchange of genetic material between two non-sister chromatids of homologous chromosomes that creates new combinations of genetic material (recombination). The frequency of cross over is directly proportional to the distance between two genes. Hence, the higher the recombination frequency the greater is the distance between the two genes. With increasing distance, the probability of linkage is decreased and that of independent assortment of the genes is increased. Hence, the genes having 50% recombination frequency can not be tightly linked. Option A is not true for these genes. The distantly located genes show independent assortment; hence option B is correct for these genes. The genes present on same chromosomes in synteny; they can undergo multiple cross over per meiosis owing to demonstrable distance between the two. Hence option C is also correct for these genes. The higher recombination frequency suggest that these genes are present far apart from each other, even on the different chromosomes. Hence option D is also correct for these genes.