This document summarizes the stages of mitosis and meiosis in eukaryotic cell division. It describes the four phases of mitosis - prophase, metaphase, anaphase and telophase - and how chromosomes are duplicated and separated. It then explains the key differences in meiosis I and II, including how homologous chromosomes pair and separate, resulting in four haploid daughter cells each with half the number of chromosomes as the original cell.
2. Interphase During the Interphase, the cell grows and synthesizes new molecules and organelles. Interphase is not part of mitosis. It consists of three generalized phases : G1, S, and G2. The cell grows (G1), continues to grow as chromosomes are duplicated (S), and grows even more as it prepares for mitosis (G2).
4. Prophase During prophase the two centriole pairs move apart until they are at opposite ends of the cell. While they move, microtubules are formed. The nuclear envelope breaks down and the spindle fibers extend across the entire cell.
5. Metaphase As the microtubules grow, they attach to the chromosomes and pull them until they align on an imaginary metaphase plate.
6. Anaphase During the anaphase the chromatids are pulled apart at the centromere by the spindle fibers, separating them as free chromosomes.
7. Telophase During telophase the spindles dissolve and a new nuclear envelope forms around both sets of daughter chromatids.
8. Interphase (Meiosis) The chromosomes duplicate. At the end, each chromosome has two identical sister chromatids attached together. The centrosome has also been duplicated by the end.
10. Prophase I Takes up 90 percent of meiotic cell division. In this phase, chromatin coils up and synapsis occurs, which is when homologous chromosomes composed of two sister chromatids composed of pairs resulting in a tetrad. Subsequently, crossing over occurs. In the end, the nuclear envelope breaks up and chromosome tetrads are moved to the center of the cell.
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12. Metaphase I The chromosome tetrads align on the metaphase plate. Each chromosome is condensed and thick with sister chromatids attached to the kinechores at the centromeres. Later, the homologous chromosomes of each tetrad are poised to move toward the opposite poles of the cell.
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14. Anaphase I The chromosomes move towards two opposite poles of the cell. Only the tetrads split up from their centromere.
15. Telaphase I/ Cytokinesis The chromosomes are at two poles of the cell. In the end, each pole has a haploid set. Each chromosome still consists of two chromatids. Cytokinesis usually occurs with Telophase 1 when two haploid daughter cells are formed.
17. Prophase II Just like before, the chromatids are linked at spindle fibers to centrioles.
18. Metaphase II The chromosomes line up between the two centrioles. This is done in both daughter cells.
19. Anaphase II The centromeres are seperated, and the daughter chromosomes are pulled toward the centrioles
20. Telophase II Now four distinct daughter cells forms, with only half the regular number of chromosomes in each. The cytoplasm now divides in cytokinesis.
