Question

A recessive allele on the x chromosome is responsible for red-green color blindness in humans. Alleles are C = normal and c = color blind. A woman with normal vision whose father is color blind marries a color-blind male. What is the probability that this couple's first son will be color-blind? A) 1/4 B) 1/2 C) 2/3 D) 3/4

Answer 1

Answer:

1/2

Explanation:

The allele for the red-green color blindness is X-linked recessive. The father of the woman was colorblind (X^cY) which means that the woman is a carrier for the allele and has genotype (X^cX). The genotype of the colorblind male would be X^cY. A cross between a carrier woman and a color-blind man would produce progeny in following ratio= 1/2 colorblind daughter: 1/2 normal daughter: 1/2 colorblind son: 1/2 normal son.

Therefore, there is a 50% probability that their first son is colorblind.