Question

Three alleles exist for coat color in rabbits: Cp, Ct, and Cz. A male Cp/Cz is crossed with a female Ct/Ct. Occasionally some rare genotypes occur. For each of the following rare genotypes, explain how they occurred: state which meiotic stage nondisjunction occurred and in which parent (male vs. female) the event occurred (example: female meiosis I). What caused the following rare genotype: Cp/Cz/Ct

Answer 1

The correct answer is male meiosis I.

Explanation:

The genotype of the offspring is Cp/Cz/Ct, that is, it possesses alleles of the parent Cp/Cz. Thus, in this parent, non-disjunction has taken place at the time of meiosis I. At the time of meiosis I, the homologous chromosomes distinguishes, and in the given case, the homologous chromosomes with this gene have failed to segregate at the time of meiosis I.

Therefore, one of the two daughter cells generated post meiosis I comprise both the homologous chromosomes and this cell after meiosis II generated gamete comprising both the alleles that associated with Ct gamete from the mother giving rise to Cp/Cz/Ct offspring.