Скачать или смотреть Lec 6 Meiosis II

Meiosis II is the second division of meiosis, a process that reduces the chromosome number by half, resulting in four non-identical daughter cells, each with half the number of chromosomes as the original cell. It follows meiosis I, which separates homologous chromosomes, and involves the separation of sister chromatids. Here's a breakdown of the stages of Meiosis II:

1. Prophase II:

Chromosomes condense, and a new spindle apparatus forms in each haploid cell (created during meiosis I).

The nuclear membrane dissolves, and spindle fibers attach to the centromeres of the chromosomes.



2. Metaphase II:

Chromosomes line up individually along the metaphase plate (the center of the cell).

The spindle fibers are fully attached to the centromeres of the chromosomes.



3. Anaphase II:

The centromeres divide, and the sister chromatids are pulled toward opposite poles of the cell.

Each chromatid is now considered an individual chromosome.



4. Telophase II:

Chromosomes begin to de-condense, and a nuclear membrane reforms around each set of chromosomes.

Cytokinesis occurs, dividing the cytoplasm and organelles, resulting in four genetically distinct haploid cells (gametes, such as sperm or egg cells).