Question

7. In humans, ABO blood type is controlled by a single gene with 2 codominant alleles (I^A and I^B) and one recessive allele (i).  The population of humans in the city of Xanadu is 7568.  1874 of these people have blood type O and 1243 of these people have homozygous blood type A.  You will need to use a three-variable Hardy-Weinberg equation for this question: p² + 2pq + q² + 2qr + r² + 2pr = 1.  Note that p + q + r = 1.

a. (2 points) What are the frequencies of the I^A, I^B, and i alleles assuming this population is randomly mating and there are no significant evolutionary forces acting on the population?

b. (2 points) Estimate how many individuals in the population have each of the following genotypes: I^Ai, I^AI^B, I^BI^B, and I^Bi.

c. (2 points) Estimate how many individuals in the population have type A, type B, type AB, and type O blood.

d. (2 points) A disease suddenly emerges that kills 60% of people with type A blood (leaving 40% alive), kills 40% of people with type AB blood, kills 10% of all people with type B blood, and kills 5% of all people with type O blood. What is the frequency of each blood type in the population now?

e. (2 points) An effective vaccine is developed so the disease only affects a single generation. Using the values for the number of survivors with type O and homozygous type A blood, determine what the allele frequencies of the I^A, I^B and i alleles will be when the population of Xanadu has again reached Hardy-Weinberg equilibrium.

Answer 1