AP BIOLOGY

Detailed explanation-1: -Mitotic nondisjunction can occur due to the inactivation of either topoisomerase II, condensin, or separase. This will result in 2 aneuploid daughter cells, one with 47 chromosomes (2n+1) and the other with 45 chromosomes (2n-1). Nondisjunction in meiosis I occurs when the tetrads fail to separate during anaphase I.

Detailed explanation-2: -Likewise, abnormal separation can occur in meiosis when homologous pairs fail to separate during anaphase I. This also results in daughter cells with different numbers of chromosomes. The phenomenon of unequal separation in meiosis is called nondisjunction.

Detailed explanation-3: -Nondisjunction can occur during either meiosis I or II, with different results (Figure 7.8). If homologous chromosomes fail to separate during meiosis I, the result is two gametes that lack that chromosome and two gametes with two copies of the chromosome.

Detailed explanation-4: -During the anaphase stage of mitosis, these chromatids separate, and one chromatid goes into each daughter cell. However, when nondisjunction occurs, the chromatids do not separate. The result is that one cell receives both chromatids, while the other cell receives neither.

Detailed explanation-5: -Nondisjunction in Meiosis 1 vs 2 Failure of homologous chromosomes to separate towards the poles during anaphase 1 is known as nondisjunction in meiosis 1. Failure of sister chromatids to separate towards the poles during anaphase 2 in meiosis is known as nondisjunction in meiosis 2.