You observe the following numbers of individuals of each genotype in a populatio

ID: 312802 • Letter: Y

Question

You observe the following numbers of individuals of each genotype in a population:

AA Aa aa

250 800 200

a. What are the observed genotype frequencies in this population?

b. What are the allele frequencies in this populations?

c. What are the expected Hardy-Weinberg genotype frequencies?

d. What is the expected number of individuals of each genotype?

e. Is this population in H-W equilibrium? Do a chi-square to test

departure from H-W equilibrium and if there is a significant deviation from HW what could explain this?

a). The total number of individuals is = 1250

The frequency of AA is = 250/1250 = 0.2

The frequency of Aa is = 800/1250 = 0.64

The frequency of aa is = 200/1250 = 0.16

b). The frequency of dominant allele, A is = frequency of AA + ½ (frequency of Aa) = 0.2 + ½ (0.64) = 0.52

The frequency of recessive allele, a is = frequency of aa + ½ (frequency of Aa) = 0.16 + ½ (0.64) = 0.48

c). The expected Hardy-Weinberg genotype frequencies are,

The frequency of AA is = 0.52*0.52 = 0.2704

The frequency of Aa is = 2*0.52*0.48 = 0.4992

The frequency of aa is = 0.2304

d). The expected number of individuals with AA genotype is = 0.2704*1250 = 338

The expected number of individuals with Aa genotype is = 0.4992*1250 = 624

The expected number of individuals with aa genotype is = 0.2304*1250 = 288

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