7. In humans, the alleles for blood type are designated I^ (A-type blood), I ^ B (B-type blood) and i (O-type blood). What are the expected frequencies of phenotypes in the following matings? Draw a Punnett square showing the results for a). a) heter A x heter B: %A %B %0 %AB b) I ^ A * I ^ B * I ^ A_{i} : c) I ^ A * I ^ A * I ^ B * I ^ B :

1. The mutant strain maroon-like has an X-linked mutant allele (X") that results in deep maroon-colored eyed in homozygous females and hemizygous males. To prove to a skeptical friend that this trait is in fact X-linked you set up a reciprocal cross against the wild type. What are the expected genotypic and phenotypic frequencies of each half of this crossing experiment? 2. What is the significance of reciprocal crossing?

1. A population of lemmings includes two varieties with regards hair colour: those with green hair and those with red hair. A cross was made between a homozygous, green-haired lemming and a homozygous, red-haired rodent. The resulting F₁ generation all had green hair. a. Which colour allele is the dominant one? How do you know? b. If a lemming from the F₁ generation was crossed with a red-haired lemming, what would be the predicted outcome? Use a genetic cross diagram or Punnet square to explain your answer. C. What ratio of offspring would you expect if lemmings from the F₁ generation were crossed with one another? Explain your answer

1) By convention, the recessive trait will determine the abbreviation used to track crosses if it is a mutant condition, since it stands out in contrast to the rest of the population. For example, if pea pods are typically green in color, a mutant condition might result in yellow pea pods; therefore, the lowercase letter ‘y’ would be used to depict the mutant state, yellow, while uppercase ‘Y’ would depict the wildtype (wt) condition, green. Remember that the mutant condition is not necessarily always recessive. 1 A) . If green is dominant wt (Y) and yellow is a recessive mutant condition (y), depict a Yy father mated with a YY mother in the Punnett.  1B)  Considering the dominant allele, what colors are the parents in the cross above? Yy = _____________________ YY = _____________________   1C) What colors are the offspring in the cross above?    1D) What is the phenotypic ratio of the offspring?  1E) What is the genotypic ratio of the offspring? (Remember, the genotypic ratio is based…