BIOL 133 Chapter Notes - Chapter 3: Intellectual Disability, Placenta, Prenatal Development
Document Summary
Meiosis why does it happen: cell division for reproduction, diploid cell (2n) 4 haploid cells(1n) Mitosis: 1(2n) 2(2n) = cloning: each daughter cell is different from others, generates genetic diversity. Meiosis i: prophase i, metaphase i, anaphase i. Telophase i: meiosis i: reduces ploidy level and separates homologous chromosomes, chromosomes w/ same size, shape, and linear arrangement of genes (can have. Crossing over: crossing over produces genetic diversity, chromosomes condense, homologous chromosomes synapse (attach to each other, crossing over can occur. # possible arrangements = 2n n=# of homologous pairs. Independent assortment: metaphase i, non-homologous chromosomes line up independently of each other. Spermatogenesis: spermatogonium (2n): precursor to sperm cells, spermatogonium (mitosis) primary spermatocyte (2n) primary spermatocyte (meiosis i) secondary spermatocyte (1n) secondary spermatocyte (meiosis ii) spermatid. Spermatogenesis: each spermatid then develops flagella and becomes individual spermatozoa, sperm are small and do not house many organelles (nucleus and mitochondria) Contains nucleus and acrosome (digestive enzymes to enter egg)