If you followed a woman's cells through meiosis, at what stage of meiosis would the amount of DNA in one of these cells be equal to the amount of DNA in one of her G1 phase (before DNA replication) kidney cells?

검증된 단계별 안내

Understand the stages of meiosis: Meiosis consists of two consecutive divisions, meiosis I and meiosis II, each with prophase, metaphase, anaphase, and telophase stages.

Recognize that during the G1 phase of the cell cycle, cells have a diploid amount of DNA, which has not yet been replicated.

Recall that DNA replication occurs during the S phase of the cell cycle, following G1 and before meiosis begins, resulting in each chromosome consisting of two sister chromatids.

Identify that during meiosis I, homologous chromosomes separate but sister chromatids do not. Thus, cells at the end of meiosis I have half the number of chromosomes, each consisting of two chromatids, which is still double the DNA content of a G1 phase cell.

Conclude that it is during meiosis II, specifically after anaphase II when sister chromatids separate, that the cells have the same amount of DNA as a G1 phase cell. Therefore, the stage where the DNA amount is equal to that of a G1 phase kidney cell is at the end of meiosis II.

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주요 개념

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Meiosis

Meiosis is a specialized form of cell division that reduces the chromosome number by half, resulting in four haploid cells from one diploid cell. It consists of two sequential divisions: meiosis I and meiosis II. During meiosis, homologous chromosomes are separated in meiosis I, and sister chromatids are separated in meiosis II, ultimately leading to the formation of gametes.

DNA Content and Cell Cycle Phases

The cell cycle consists of several phases, including G1, S, G2, and M. In the G1 phase, cells have a diploid amount of DNA (2n), which is the normal state before DNA replication. After the S phase, the DNA content doubles (4n) as each chromosome is replicated, but during meiosis, the DNA content is halved again during the first meiotic division.

Meiosis I and DNA Amount

During meiosis I, specifically at the end of prophase I and metaphase I, the cells still contain the diploid amount of DNA (2n) because the DNA has been replicated but not yet separated. Therefore, at this stage, the amount of DNA in the cells undergoing meiosis is equal to that of a G1 phase cell, which also has a diploid DNA content before replication.