Ch 10 covers the cell cycle and its phases, mitosis (equational division for growth and repair), and meiosis (reductional division for gamete formation), along with their significance.
Cell cycle: Interphase (G1: growth, S: DNA replication, G2: preparation) + M phase (mitosis + cytokinesis). Mitosis: prophase (chromatin condenses), metaphase (chromosomes at equator), anaphase (centromeres split, chromatids separate), telophase (nuclear envelope reforms). Result: 2 genetically identical diploid (2n) daughter cells. For growth, repair, asexual reproduction.
Meiosis I (reductional): homologous chromosomes separate. Prophase I: crossing over (exchange of segments between homologues → genetic variation). Metaphase I: bivalents at equator. Anaphase I: homologues separate (not chromatids). Meiosis II: similar to mitosis (chromatids separate). Result: 4 genetically different haploid (n) cells. For gamete formation. Crossing over + independent assortment → variation.
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Meiosis: (1) halves the chromosome number (2n → n) so that when two gametes fuse at fertilisation, the normal diploid number is restored, (2) creates genetic variation through crossing over and independent assortment, which is essential for evolution and adaptation, (3) produces gametes (eggs and sperm) or spores required for sexual reproduction.
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