1. Assume that A, B, D and E are autosomal genes on different chromosomes (so they assort independently). If a mating occurs between two individuals with the following genotypes: AabbDdEe x AaBbDdEe
(a) What is the probability that one of the offspring will have the genotype aaBbDdEE? (show a Punnett square for each trait and all of your math!)
(b) What is the probability that one of the offspring will be heterozygous for each gene?
(c) Assume that each trait is a case of complete dominance. What is the probability that an offspring will exhibit the recessive phenotype for each trait?
2. Two true-breeding parents of a fish species are crossed. One parent has long, spotted fins and the other has short, unspotted fins; all of their F1 offspring have long, spotted fins. The gene for fin length and the gene for spots assort independently. If two F1 individuals are crossed and 1,000 F2 offspring result, approximately how MANY of the F2 offspring are expected to have long fins with no spots?
(a) Define all allele symbols:
(b) What were the original true-breeding parents' genotypes?
(c) What are the genotypes of the two F1 parents?
3. Assume that chipmunks can have tails with two black stripes (a dominant allele, B), or a black and a white stripe (recessive allele, b) and that having patches of fur on their ear ("ear tufts") is determined by a recessive allele (e), with plain ears resulting from a dominant allele (E).
(a) What is the genotype of a possible gamete from a chipmunk that is heterozygous for both traits?
(b) Which is a possible genotype for chipmunk with a black & white striped tail and plain ears?
4. What is a possible offspring from parents that are HHGGRR x hhGgrr?
5. What is a possible gamete from a parent that is FfTtBBDd?
6. As mentioned above in #3, chipmunks can have tails with two black stripes (a dominant allele, B) or a black and a white stripe (due to a recessive allele, b) and that having patches of fur on their ear ("ear tufts") is determined by a recessive allele (e), with plain ears resulting from a dominant allele (E). If a chipmunk that is homozygous recessive for the tail trait and heterozygous for ear morphology mates with a chipmunk that is heterozygous for both tail and ear morphologies, then what are all possible phenotypes among offspring for these two traits and the expected proportion (fraction) of each phenotype? Show all Punnett squares, branch diagram, and all math.
(a) Parental genotypes:
(b) Both Punnett squares:
(c) Branch diagram:
(d) Final answer:
7. In flying spaghetti monsters, the red-wing allele (R) is dominant to the blue-wing allele (r). As with humans, the chance that an offspring will be either male or female (a second trait) is always ½. A red-winged parent (who had a father with blue wings) mates with a blue-winged parent.
Parental genotypes for the wing trait:
Punnett square for the wing trait:
(a) What is the probability that this couple will have a blue-winged son, a red-winged daughter, and a red-winged son (in that order)?
(b) What is the probability that this couple will have two red-winged sons or two blue-winged daughters?