Biology, 27.07.2019 18:30 karlacr5117

If 2n = 10, how many homologous chromosomes are in each cell at the beginning of prophase ii of meiosis?

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Meiosis occurs in two phases. Since the first phase is the reductive one, before prophase ii, there are 5 homologous chromosomes in each cell.

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.

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.

Since the first phase is the reductive one, before prophase ii, there are 5 homologous chromosomes in each cell. The genetic material was divided during the first phase.

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If 2n = 10, how many homologous chromosomes are in each cell at the beginning of prophase ii of meio...

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