Problem Set 1: Mendelian Segregation of Individual Genes

1. A pea plant with red flowers is mated with a pea plant with white flowers. Half of the offspring have red flowers, and half have white. If the allele for red flower color is dominant to the allele for white flower color, what were the genotypes of the parents?

2. Suppose a pea plant has three alleles for flower-color, red, yellow, and white. Red is dominant to yellow and white, and yellow is dominant to white. If a plant with one red allele and one white allele is mated to a plant with one yellow allele and one white allele:
a. what percentage of the offspring will have red flowers?
b what percentage of the offspring will have yellow flowers?
c. What percentage of the offspring will have white flowers?

3. In humans, there is a gene locus for blood type. The three alleles are A, B, and O. A and B are comdominant to each other and dominant to O. Genotypes AA and AO give blood type A. Genotypes BB and BO give blood type B. Genotype AB gives blood type AB. And genotype OO gives blood type O.
A man of genotype AB marries a woman of genotype BO. If they have eight children:
a. On average, how many will have blood type A?
b. On average, how many will have blood type B?
c. On average, how many will have blood type AB?

4. A woman with blood type B marries a man with blood type O. If they have a child of blood type O, what is the probability that the mother's genotype is BO?
If they have a child of blood type B, can you compute the probability that the mother's genotype is BO; that the mother's genotype is BB? Why?/why not?

5. Two carriers for the mutant CF allele marry and have a child. What is the probability that the child will have CF; that the child will be phenotypically normal; that the child will be a phenotypically normal carrier?