Question

A student proposes that left-handedness is a recessive trait, and therefore hidden in much of the human population. A survey of 36 students finds that 27 (0.75) are right-handed and 9 (0.25) are left-handed. Using the Hardy-Weinberg formula, what would be the expected genotype frequencies and allele frequencies in this theoretical population?

Answer 1

Frequency of homozygous dominant genotype = 0.25

Frequency of heterozygous dominant genotype = 0.50

Frequency of homozygous recessive genotype = 0.25

Frequency of allele for left handedness = 0.5

And, frequency of allele for right handedness = 0.5

Step-by-step explanation:

Allele frequencies:

Given that the frequency of recessive trait (left-handedness) is (q2) = 0.25

Frequency of recessive allele (q) = square root of 0.25 = 0.5

Since p+q= 1; so, p= 1-q = 1 - 0.5 = 0.5

Therefore, frequency of allele for left handedness (q) = 0.5

And, frequency of allele for right handedness (p) = 0.5

Genotype frequencies:

Frequency of homozygous dominant genotype (p2) = 0.5 x 0.5 = 0.25

Frequency of heterozygous dominant genotype (2pq) = 2 x 0.5 x 0.5 = 0.50