- Hardy-Weinberg tutorial (allele frequencies):

- If 98 out of 200 individuals in a population express the recessive phenotype, what percent of the population are homozygous dominant?
- 49% (wrong)
- 70% (wrong)
- 30% (wrong)
- 42% (wrong)
- 9% <==== correct

**Solution**:- Recessive phenotype implies homozygous genotype.
*q*= 98 / 200 = 0.49^{2} *q*= 0.7*p*+*q*= 1*p*+ 0.7 = 1*p*= 0.3*p*=^{2}*0.3*= 0.09^{2}

- If 98 out of 200 individuals in a population express the recessive phenotype, what percent of the population are heterozygotes?
- 49% (wrong)
- 70% (wrong)
- 30% (wrong)
- 42% <==== correct
- 9% (wrong)

**Solution**:- Recessive phenotype implies homozygous genotype.
*q*= 98 / 200 = 0.49^{2} *q*= 0.7*p*+*q*= 1*p*+ 0.7 = 1*p*= 0.3- 2
*pq*= 2 (0.7 * 0.3) = 0.42 - double check:
*p*+ 2^{2}*pq*+*q*= 1?^{2} - double check: 0.09 + 0.42 + 0.49 = 1.

**Brown hair (B) is dominant to blond hair (b). If there are 168 brown hairs in a population of 200:**

- What is the predicted frequency of heterozygotes?
- 16% (wrong)
- 40% (wrong)
- 60% (wrong)
- 48% <==== correct
- 84% (wrong)

**Solution**:- BB + Bb = 168 / 200 = 0.84 = brown hairs
- bb = 1 - 0.84 = 0.16 =
*q*blond hairs^{2} *q*= 0.4*p*= 1 -*q*= 1 - 0.4 = 0.6- 2
*pq*= 2 (0.4 * 0.6) = 0.48

- What is the predicted frequency of homozygous dominant?
- 16% (wrong)
- 40% (wrong)
- 60% (wrong)
- 48% (wrong)
- 36% <==== correct

**Solution**:*p*= 0.6^{2}^{2}= 0.36

- What is the predicted frequency of homozygous recessive?
- 16% <==== correct
- 40% (wrong)
- 60% (wrong)
- 48% (wrong)
- 36% (wrong)

**Solution**:*q*= 0.4^{2}^{2}= 0.16- double check:
*p*+ 2^{2}*pq*+*q*= 1?^{2} - double check: 0.6
^{2}< + 2 (0.6 * 0.4) + 0.4^{2}= 0.36 + 0.48 + 0.16 = 1.

**If blonds occur in 36% of the population:**

- What is the allele frequency for b?
- 36% (wrong)
- 60% <==== correct
- 40% (wrong)
- 16% (wrong)
- 48% (wrong)

**Solution**:- bb =
*q*= 0.36^{2} *q*= b = 0.6

- What is the allele frequency for B?
- 36% (wrong)
- 60% (wrong)
- 40% <==== correct
- 16% (wrong)
- 48% (wrong)

**Solution**:*p*+*q*= 1*p*+ 0.6 = 1*q*= 1 - 0.6 = 0.4

- What is the predicted frequency of heterozygotes?
- 36% (wrong)
- 60% (wrong)
- 40% (wrong)
- 16% (wrong)
- 48% <==== correct

**Solution**:- 2
*pq*= 2 (0.6 * 0.4) = 0.48

- What is the predicted frequency of homozygous dominant?
- 36% (wrong)
- 60% (wrong)
- 40% (wrong)
- 16% <==== correct
- 48% (wrong)

**Solution**:*p*+ 2^{2}*pq*+*q*= 1^{2}*p*+ 0.48 + 0.36 = 1^{2}*p*= 1 - (0.48 + 0.36)^{2}*p*= 1 - 0.84^{2}*p*= 0.16^{2}