Recall Mendels law of segregation for autosomal alleles D and d and consider the behavior of homologous chromosomes in meiosis.

Suppose a crossover occurs between the homologous chromosomes. At what stage or stages of M phase could alleles D and d segregate?

A) prophase
B) telophase I or II
C) metaphase I
D) anaphase I or II

D

Explanation:

Homologous chromosomes are similar but non-identical chromosomes received from each parent. They are non-identical in the sense that they may contain different alleles for the same gene. For example, in this case, D and d alleles on each homologue. These homologous chromosomes are usually involved in meiotic division, which occurs in a two-step division process; Meiosis I and II.

In meiosis I, homologous chromosomes separate/pulls apart, specifically during the anaphase stage. Alleles D and d borne on the HOMOLOGOUS pair of chromosomes are separated in the process with each of them going to either pole of the cell, according to Mendel's law of segregation.