Name______Date______
Punnett Square and Pedigree Problems 20 points
1. In fruit flies, the gene that controls eye color has two alleles. The dominant allele (R) is responsible for red eyes and the recessive allele (r) is responsible for white eyes.
a. Suppose a fly that has two red alleles (RR) is crossed with a fly that has two white alleles (rr). (Answer the questions below and show your work by making the appropriate Punnett Square) What is the probability that the offspring will have:
i. red eyes? ______
ii. white eyes? ______
iii. one of each allele? ______
b. What would be the result of a cross between two flies, each fly possessing one of each allele (Rr X Rr)? Show your work below.
2. a. Cystic Fibrosis (C.F) is a disease inherited as an Autosomal recessive trait. A family has three children, two boys have the disease and one girl does not have the disease. Draw a pedigree for the family indicating: normal, carriers and C.F. affected individuals.
b. Did the parents have the predicted outcome of probability for having children with and without this disease? (Explain what the expected probability is and compare it to the actual outcome). Show your work.
c. What could be the genotype of the girl that doesn’t have the disease?
3. A gene, called the I gene, produces a protein on the cell membrane of red blood cells and is responsible for our different blood types (or groups). This gene is even more of an exception to Mendel’s work because it has three different alleles which give up four different blood types, A, B, O and AB. The three alleles are IA, IB and i. Both IA and IB are dominant over I, but neither IA nor IB are dominant over the other. Using the table below, answer the questions that follow and be sure to show your work.
a. What possible blood types will be seen among the biological children of a type AB father and a heterozygous type B mother? Show your work.
b. What possible blood types will be seen among the biological children of a type O mother and a heterozygous type A father? Show your work.
c. Do you know what your blood type is? If so, what phenotype and genotype possibilities could your parents be? If you don’t know your blood type, make up a scenario different than the questions above.