The cell cycle, the stages of mitosis, the role of meiosis in producing genetic variation, and the key differences between the two.
Cells divide to grow, repair and reproduce. The cell cycle has interphase (the longest phase: growth and DNA replication) and a division phase (mitosis then cytokinesis).
Mitosis
Mitosis produces two genetically identical diploid daughter cells. Stages (PMAT):
- Prophase — chromosomes condense and become visible (each two sister chromatids); the nuclear envelope breaks down; spindle fibres form.
- Metaphase — chromosomes line up on the equator, attached to spindle fibres by their centromeres.
- Anaphase — centromeres split; spindle fibres pull sister chromatids to opposite poles.
- Telophase — chromatids reach the poles; nuclear envelopes reform; chromosomes decondense.
Cytokinesis then divides the cytoplasm into two cells. Mitosis is used in growth, repair and asexual reproduction.
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