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If a cell has a diploid number of 50, how many chromosomes are present in the nucleus at the beginning of meiosis? How many chromosomes are present in each resulting nucleus at the end of meiosis?

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Final answer:

During meiosis of a cell with a diploid number of 50, there would be 50 chromosomes at the start, and each of the four resulting daughter cells would have 25 chromosomes. Meiosis consists of two divisions resulting in haploid cells that form gametes, with genetic diversity increased due to processes such as crossing-over.

Step-by-step explanation:

Meiosis is a type of cell division that reduces the number of chromosomes by half, resulting in the formation of haploid gametes from a diploid parent cell. It consists of two successive divisions: Meiosis I and Meiosis II. If a cell has a diploid number of 50, at the beginning of meiosis, there would be 50 chromosomes present in the nucleus. By the end of meiosis, each of the resulting four nuclei would contain 25 chromosomes, reflecting the haploid number.

Differences Between Haploid and Diploid Cells

A diploid cell (2n) contains two complete sets of chromosomes, one from each parent, while a haploid cell (n) contains only one set of chromosomes. During sexual reproduction, two haploid gametes combine to form a diploid zygote, restoring the diploid number of chromosomes.

Meiosis I and Meiosis II

Meiosis I and Meiosis II each consist of the phases prophase, metaphase, anaphase, and telophase, alongside cytokinesis. In Meiosis I, homologous chromosomes separate resulting in two haploid cells. Meiosis II closely resembles mitosis, where sister chromatids separate to form four unique haploid cells.

Crossing-over and Genetic Diversity

Crossing-over occurs during prophase I of meiosis I, where non-sister chromatids of homologous chromosomes exchange segments. This process increases genetic diversity by producing new allelic combinations.

Meiosis Outcome

The outcome of meiosis is the formation of four genetically unique haploid daughter cells from a single diploid parent cell. These haploid cells are poised to become gametes, contributing to the genetic variation essential for evolution and adaptation.

User Victor Istomin
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Answer:

Beginning of meiosis: 50 chromosomes

Chromosomes in each of the nucleus formed by meiosis: 25

Step-by-step explanation:

Meiosis is a reduction division as it has two successive divisions without any intervening S-phase. It forms a total of four daughter nuclei each having half the chromosome number as present in the parent cell at the beginning of the process.

If a cell with 2n=50 enters meiosis, the segregation of homologous chromosomes to the opposite poles during anaphase-I of meiosis I would result in the reduction of chromosome number to the half in each of the two daughter nuclei formed by the end of the meiosis-I.

Meiosis-II is just like mitosis and maintains the chromosome number. So, the two daughter nuclei enter the meiosis-II and form a total of 4 daughter nuclei each of which has 25 chromosomes.

User Vova Rozhkov
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