ANTHR-140 Lecture Notes - Lecture 4: Sister Chromatids, Down Syndrome, Meiosis
15 Jun 2020
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Occurs during growth and repair/ replacement of tissues. Result 2 identical copies: interphase: majority of lifetime. Dna chills in cell until replication starts in phase: prophase: chromosomes visible with 2 sister chromatids, metaphase: chromosomes line up single file along equator of cell, anaphase: sister chromatids separate, telophase: 2 daughter cells (diploid) 2 rounds of division 4 daughter cells. Interkinesis: when the haploids appear and are genetically dissimilar: prophase ii- no further replication of dna, metaphase ii, anaphase ii- sister chromatids separate, telophase ii, 4 haploid gametes genetically dissimilar. In meiosis i end up with 1 unusable gametes. In meiosis ii end up with two usable gametes and 2 unusable. Law of segregation: paired hereditary factors segregate randomly during formation of the gametes. Law of independent assortment: factors controlling for inheritance of different traits assort independently from one another. Exception: applies to genes located on different chromosomes but not genes on the same chromosome. Crossing over and random assortment genetic recombination.
