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Meiosis is the process that produces haploid gametes from diploid cells in the gonads. As a diploid cell progresses through the stages of meiosis I and meiosis II, at what point do the cells first become haploid

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Answer:

A

Explanation:

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Meiosis occurs in two phases. Meiosis I is the reductive phase, while meiosis II is non-reductive. The point at which the cells first become haploid is at the end of meiosis I, after homologous chromosomes separate.

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Through Meiosis, a diploid cell (2n) produces four haploid daughter cells (n).  

After DNA replication there are two meiotic phases.  

  • The first one is a reductive phase, in which homologous chromosomes separate.  

  • In the second phase, the cell suffers a new, not reductive division.  

1. In the first phase, Meiosis I:  

  • Prophase I: Chromosomes condensate and become visible. Occurs crossing-over between homologous chromosomes. Crossin-over makes the daughter cells to be genetically different from the original one.  

  • Metaphase I: Homologous chromosomes randomly align in the equatorial plane.  

  • Anaphase I: In this phase occurs the division and independent separation of homologous pairs. Each chromosome migrates to different poles. This separation generates different chromosomal combinations in the daughter cells.

  • Telophase I: Chromosomes of homologous pairs are already in the corresponding poles, and the nuclear membrane forms again in each pole.

Cytokinesis occurs

2. In the second phase, Meiosis II:  

  • Prophase II: Chromosomes condensate again and become visible.  

  • Metaphase II: Chromosomes join the spindle apparatus and migrate to the equatorial plane, where they randomly line up. Sister chromatids are holden together until they reach the Anaphase.  

  • Anaphase II: Centromeres divide, chromatids get separated, and each of them goes forward an opposite cellular pole.

  • Telophase II: Once in the poles, the chromosomes become lax again, and the nuclear membrane forms again.  

Cytokinesis occurs.  

To answer this question, focus your attention on Meiosis I. During the anaphase homologous chromosomes separate. After this point, the nuclear membrane forms in the telophase, followed by cytokinesis. The result is two haploid cells.

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