Question

What kinds of gametes, and in what proportions can be made by a person who develops from an egg carrying alleles A and B and a sperm carrying a and b if the teo loci are on different ( nonhomologous) chromosomes? What kinds of gametes , and in what proportions , can be made by the same person if the loci are on the same chromosomes?

Answer 1

Case I: When the two loci are on different non-homologous chromosomes

Then the individual will 4 gametes since each allele is situated on a different chromosome and thus can assort independently. Thus it will produce 4 types of gametes - AB, Ab, aB and ab. Each gamete will have an equal proportion of 1/4 or 25%.

Case II: When the two loci are on same chromosomes

Since the alleles are present on the same chromosome, even independent assortment will produce the same parental combination.

So only 2 types of gametes are produced with parental combinations AB or ab. Proportion of each gamete will be 1/2 or 50%.