Chapter 20, Problem 30P

Summary Introduction

To analyze:

The presence of cheek and chin dimples is dominant to the lack of dimples, and the ability to taste the compound PTC is dominant to the failure to taste the compound, in humans. Both these qualities are autosomal and unlinked. The allele frequencies for dimples are $\text{D=0}\text{.62}$ and for tasting, $\text{d=0}\text{.38}$. $\text{T=0}\text{.76}$ and $\text{t=0}\text{.24}$ the allele frequencies. From this given information, the question is asked to determine

Calculate the frequency of genotypes for each gene and the frequency of each phenotype.

Estimate the expected frequencies of the four probable phenotype combination: Dimpled nontasters, dimpled tasters, undimpled tasters, and undimpled nontasters.

Introduction:

Hardy Weinberg principle is considered as one of the cornerstones of population genetics. The group of individuals who can interbreed is termed as population. The gene pool is a part of the population. It consists of genes and alleles of the members of a population. Hardy Weinberg principle provides a model that expresses the frequency of alleles and genotypes of a population whose size is infinite. According to this principle, random mating takes place in the population that allows the determination of genotype frequencies using allele frequency. Gene flow never introduces new alleles. The frequency of alleles remains the same over time.

Hardy-Weinberg explains that allelic frequency in a population can be maintained but population should fulfill some criteria i.e. there should be random mating, no mutation, large size population, no selection etc. Hardy-Weinberg proposes the mathematical equation to calculate the allelic and genotypic frequency.

Hardy-Weinberg mathematical equation to calculate the allelic and genotypic frequency is

${\text{p}}^{\text{2}}{\text{ + 2pq + q}}^{\text{2}}\text{ = 1}$