During which phase of meiosis do sister chromatids fail to separate during non-disjunction?

The correct answer pertains to Anaphase 2, a critical phase in meiosis where sister chromatids typically separate and move toward opposite poles of the dividing cell. Non-disjunction refers to the failure of these sister chromatids to properly separate, leading to an unequal distribution of chromosomes. When this failure occurs during Anaphase 2, it results in gametes that have an abnormal number of chromosomes, which can lead to genetic conditions in offspring when these gametes participate in fertilization.

In contrast, during Anaphase 1, homologous chromosomes are pulled apart rather than sister chromatids. Non-disjunction at this stage involves homologous chromosomes failing to separate, which also leads to an abnormal distribution of chromosomes but does not involve sister chromatids specifically. Prophase 1 is primarily the stage where homologous recombination occurs, and Metaphase 2 involves the alignment of sister chromatids at the metaphase plate, but does not typically present the opportunity for non-disjunction since that event is defined by the separation process in Anaphase 2.