Question

Suppose the human trait for dimplesis controlled by a simple dominant and recessive relationship at one locus. You wanted to determine the frequency of people with dimples in the city of Doral. Of the 1500 people you surveyedin downtown Doral, 1172 have dimples. Calculate the frequency of the having dimples –dominant allele,D–and the heterozygous genotype, Dd. Express the frequencies in decimal form rounded to the nearest thousandth. Assume the population in the city of Doralis in Hardy-Weinberg equilibrium for this trait.

Answer 1

DD and Dd - dimplesis / dd - No dimplesis

It is Hardy-Weinberg equilibrium for this trait. So, P = Dominant and q - Recessive.

P2 + 2pq = 1172 / 1500 = 0.781

P2 + 2pq + q2 = 1

There fore q2 = 1-0.781 = 0.219

q = 0.467

P+q = 1    So p=1-q    p=1-0.467    p = 0.533

P² = 0.284

frequency for heterozygous = 2pq = 2 X 0.533 x 0.467 = 0.497

frequency for heterozygous 2Dd= 0.497

frequency for homozygous dominant DD= 0.284

frequency for homozygous recessive dd = 0.219