BIOC15H3 Lecture Notes - Lecture 7: Sister Chromatids, Seminiferous Tubule, Centromere
18 Nov 2013
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1: animal cell cleavage furrow (contractile ring) is formed that separates the elongated cell into 2 daughter cells, plant cell cell plate formed which separates the cell into 2 daughter cells. Leptotene chromosomes begin to condense and thicken, becoming visible as discrete structures (sister chromatids not yet visible under microscope) Zygotene chromosomes cleary visible and begin pairing with homologous chromosomes along the synaptonemial complex to form a bivalent (tetrad) Pachytene full synapsis of homologs; recombination nodules appear along the synaptonemal complex. Diplotene tetrads appear to pull apart slightly but remains connected at crossover sites (chiasmata) Meiosis ii: prophase ii chromosomes condense, metaphase ii chromosomes align at the metaphase plate, anaphase ii sister chromatids move to opposite spindle poles, telophase ii nuclear membrane reforms and cytokinesis follows. Meiosis 3 significant results (page 99: haploid nuclei from the starting diploid cell, each chromosome (maternal or paternal) has an equal probability of ending up in a given daughter cell after.
