Which of the following processes occurs during the second meiotic division (Meiosis II)?
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In Meiosis II, just like mitosis, the sister chromatids of each chromosome are separated, resulting in four genetically unique haploid cells. It is important to distinguish between Meiosis I and II, as they perform different roles in the division of genetic material.
Meiosis comprises two consecutive divisions: Meiosis I and Meiosis II, each with specific roles:
Meiosis I: This reduction division segregates homologous chromosomes, producing two haploid cells. Crossing over, a source of genetic variation, takes place here.
Meiosis II: This division is analogous to mitosis, separating the sister chromatids of each chromosome to yield four haploid cells.
Analyzing the provided options:
Option (1): The separation of homologous chromosomes occurs in Meiosis I, not Meiosis II. During Meiosis I, homologous chromosomes are distributed to the two resulting daughter cells.
Option (2): Sister chromatids are separated during Meiosis II. This is the defining event of Meiosis II, where each haploid cell from Meiosis I undergoes further division to separate sister chromatids, ultimately producing four haploid cells.
Option (3): DNA replication precedes Meiosis I (during interphase's S phase). No DNA replication occurs between Meiosis I and Meiosis II.
Option (4): Crossing over occurs during Prophase I of Meiosis I, not Meiosis II. This process is crucial for genetic variation and involves the exchange of genetic material between homologous chromosomes.
Consequently, Option (2) is the correct answer, as sister chromatids are separated during Meiosis II.