Bio117-07 Genetics i&II Slidetext

Bio117-07 Genetics i&II Slidetext - 1. Genes,...

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1. Genes, Phenotypes and Selection How gene interactions within the genome play a role in evolutionary processes 2. Review: Meiosis results in variable gametes A. “Crossing over” between homologues B. Random assortment of homologues to daughter cells C. Random assortment of sister chromatids to final gametes 3. (how variable?) 4. Other sources of genotypic variation Mutation Replication errors a) non-disjunction b) unequal crossing over b. Huntington’s chorea…abnormal no CAG repeats in one gene where the no. of repeats determines how early and how deleterious the disease is. Possibly due to unequal crossing over between homologues, such that one copy gets more than normal repeats. And the condition is dominant. If the person has one allele with >35 repeats, the syndrome occurs. 30-70 individuals/million people BUT can be found at high frequency in individual populations Lake Maracaibo, Venezuela, Some villages >50% affected.) 5. Inheritance, Mendel and peas Gregor Mendel (b 1822) “gardener” and trained physicist in Austrian monastery http://members.shaw.ca/mcfetridge/darwin.html 6. Mendel’s Experiments Blending inheritance vs. “Inheritance of acquired characters” A propitious choice of organism (Pisum varieties ) 7. Experimental evidence against blending characters
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(Direction of cross didn’t matter--Used two pure breeding lines Intermediates not seen Wrinkled seeds reappeared in “F2” generation (F1 x F1) Something is passed on even if not seen in phenotype currently--Proposal of dominance and recessiveness) 8. Experimental evidence against
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Bio117-07 Genetics i&II Slidetext - 1. Genes,...

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