Question

In a certain population of 540 cats, a single gene with two alleles controls thickness of the cats' fur. Allele C provides for thick fur and is dominant, and c provides thin fur. In this population, 49 cats have thin fur. What are the frequencies of the two alleles?

Answer 1

The frequency of the recessive genotype (thin fur) = 49/540= 9%. So q2 = 0.09

Take the square root of 0.09 to get the frequency of this allele: q = 0.3

p + q = 1, so p = 0.7

Frequencies for both alleles for the population of cats are p = 0.7, q = 0.3, where p is the allele for thick fur and q is the allele for thin fur.

Answer 2

C = p, c = q, cc = q2
q2 = 49/540 = .091, srq2 = q = sr.091
q = .30
p = 1-.30 = .70
So frequency of C = .70
frequency of c = .30