Question

Suppose that after the cell below undergoes meiosis i and meiosis ii, the result is one gamete with two chromosomes, two gametes with three chromosomes, and one gamete with four chromosomes. what has occurred? (click on the correct answer.)

Answer 1

The correct answer for the question is Non-disjunction. Non-disjunction occurs in cell division when chromosomes do not divide properly. It can occur during mitosis, meiosis I and meiosis II. In mitosis it occurs when sister chromatids fails to separate in Anaphase. The result is that one cell receives both chromatids, while the other receives neither. Each daughter cell then has an abnormal number of chromosomes when mitosis is complete; one cell has an extra chromosome, while the other is missing one. In anaphase of meiosis I, it happens when a pair of homologous chromosomes does not separate. In meiosis II, it happens when a pair of sister chromatids fails to separate properly during anaphase of meiosis II, one daughter cell will have an extra chromosome and one daughter cell will be missing a chromosome.