Question

Problem 4)   About 7% of men in a population are red-green colour blind due to a sex-linked recessive gene. Assuming random mating in the population with respect to colour blindness;

a) What percentage of women would be expected to be colour blind?

b) What percentage of women would be expected to be heterozygous?

c) What percentage of men would be colour blind in the next generation?

Answer 1

Problem 4)   About 7% of men in a population are red-green colour blind due to a sex-linked recessive gene.

What percentage of women would be expected to be colour blind?

Let p be the dominat allele

q be the recessive allele

If 7% of men in a population are red-green colour blind due to a sex-linked recessive gene, which means

q= 0.07

According to Hardy-Weinberg equation p+q = 1

Therefore, p = 1-q = 1-.07 = 0.93

The fequency of X linked gene in male is q, whereas in female is q2.

Frequency of color blind in female is (0.07)2= 0.0049

Therefore the expected % of female to be colour blind is 0.49%

What percentage of women would be expected to be heterozygous?

Frequency of heterozygous is denoted by 2pq = 2*0.07*0.93 = 0.13.

Therefore percentage of heterozygous female is 13%

What percentage of men would be colour blind in the next generation?

If the frequency follows Hardy-Weinberg equation, the distribution of allele will not change. Therefore, the percentage of color blind men in the next generation would be 7%.