A single diploid cell containing 46 chromosomes underwent meiosis and produced four daughter cells, two with 22 chromosomes and two with 24 chromosomes. An error in which of the following stages of meiosis would most likely explain this result?

Question

A single diploid cell containing 46 chromosomes underwent meiosis and produced four daughter cells, two with 22 chromosomes and two with 24 chromosomes.  An error in which of the following stages of meiosis would most likely explain this result?

Quizplus · Accepted Answer

11ecba2d_101d_8f4a_a3bf_e799da268785_MD0008_00 In eukaryotic organisms, gametes (eggs, sperm) form via meiosis, a process of cellular division resulting in the production of four haploid (1N) daughter cells from a single diploid (2N) parental cell. Meiosis occurs in two stages, meiosis I and meiosis II, each of which is composed of prophase, metaphase, anaphase, and telophase followed by cytokinesis (cell division): Meiosis I: In prophase I, the nuclear envelope of a diploid parental cell disintegrates and homologous chromosomes (each consisting of two sister chromatids) pair up. In the phase that follows (metaphase I), these chromosomes align in the middle of the cell (ie, at the metaphase plate). The chromosomes are pulled to opposite poles of the cell by the meiotic spindle in anaphase I. The nuclear envelope then reforms in telophase I and the cytoplasm of the cell divides (cytokinesis) to yield two haploid daughter cells. Meiosis II: A process similar to meiosis I occurs in this stage, with the exception that it occurs in the previously formed haploid daughter cells. Following nuclear envelope disintegration in prophase II, chromosomes align at the metaphase plate during metaphase II. However, in anaphase II sister chromatids (not homologous chromosomes) are pulled to opposite poles of the cell by the meiotic spindle. Reformation of the nuclear envelope in telophase II and cell division (cytokinesis) of each cell yields four haploid daughter cells. If a diploid cell with 46 chromosomes undergoes meiosis, four haploid daughter cells should be produced with each containing 23 chromosomes. However, in the given scenario two daughter cells have an extra chromosome and two daughter cells are missing a chromosome. Such a finding is most likely due to chromosomal nondisjunction, which occurs when either homologous chromosomes (during anaphase of meiosis I) or sister chromatids (during anaphase of meiosis II) fail to separate to opposite poles of the cell. Chromosomal nondisjunction during anaphase I may produce one daughter cell with an extra homologous chromosome (24 chromosomes) and one daughter cell missing a chromosome (22 chromosomes) (Choices A, B, and C). Division of these cells in meiosis II would yield two cells with 22 chromosomes and two cells with 24 chromosomes. Educational objective: During meiosis, chromosomal nondisjunction occurs when homologous chromosomes (in meiosis I) or sister chromatids (in meiosis II) fail to separate to opposite poles of the cell during anaphase, leading to extra chromosomes in some daughter cells and missing chromosomes in others.

A Single Diploid Cell Containing 46 Chromosomes Underwent Meiosis and Produced