Question

If alleles of two different genes assort independently during gamete formation then what should be the phenotypic ratio in the F2 generation according to Mendelian genetics?

Answer 1

Answer:

9:3:3:1

Explanation:

If alleles of two genes separate randomly during anaphase-I of meiosis, some new combinations of the alleles are formed in the gametes. A heterozygous genotype for two loci (let's support TtRr) produces a total of four types of gametes in 1:1:1:1 ratio (TR, Tr, tR, and tr). The random fusion of these gametes from two double heterozygous parents (TtRr x TtRr) gives a phenotype ratio of 9:3:3:1. Here, 9/16 F2 progeny exhibit dominant phenotype for both loci while 1/16 exhibits recessive phenotype for both the genes. Rest 3/16 and 3/16 F2 progeny express dominant trait for one gene and recessive for the other.