Question

Non-disjunction takes place when _____

A) Cells that can no longer divide.
B) Chromosomes don't split properly during anaphase.
C) Uncontrolled cell division.
D) Cells divide normally but have altered DNA.

Answer 1

Nondisjunction occurs when homologous chromosomes or sister chromatids fail to separate during meiosis, leading to aneuploidy. It can happen in both meiosis I and II, resulting in gametes with abnormal chromosome numbers.

Step-by-step explanation:

Nondisjunction is the process that occurs when homologous chromosomes or sister chromatids fail to separate properly during meiosis. This event leads to gametes with an abnormal number of chromosomes, a situation known as aneuploidy. There are two types of nondisjunction that can occur:

1. Durmeiosis I, when homologous chromosomes do not separate, resulting in n+1 and n-1 gametes.
2. During meiosis II, when sister chromatids do not separate, also leading to gametes with n+1 or n-1 chromosomes.

It is important to note that nondisjunction can ultimately result in offspring with genetic disorders, such as Down syndrome or Turner syndrome, which are related to an abnormal chromosome count.