BISC 102 Study Guide - Final Guide: Spindle Apparatus, Sister Chromatids, Genetic Recombination
19 Jan 2018
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Lec 9: meiosis: asexual vs sexual reproduction. Asexual: reproduce without sex (ie. without fertilization or conjugation) Sexual: fertilization to produce a genetically novel individual. 50% genes passed to offspring from each parent. Meiosis ii separates sister chromatids: paradox of sex. Female halves genetic contribution to offspring by breeding with male. Genetic recombination (new combos of alleles): crossing over, independent assortment, random fertilization of any egg from one parent with any sperm of another parent. Speeds up evolution: sexual populations adapt more quickly to changing environments. Purges deleterious (harmful) alleles = lost from population: chromatin. Chromosomes loosely arranged (not condensed), in chromatin form. Replicated chromosomes condense (chromatin of each chromosome folds + coils) Transcription stops bc enzymes can t access tightly packed. Tetrad = pair of replicated chromosomes: metaphase i. Each replicated chromosome lines up, joined with its homolog. Independent assortment: 3 pairs of chromosomes, there are 2^3 = 8 possible combinations. Shuffles maternal + paternal chromosomes: anaphase i.
