Unformatted text preview: possible gamete types: A2 B2 A1 B1 A1 B1 A2 B2 A1 GAMETES A1 B1 A2 B2 A1 B2 A2 B1 B1 Where do A1B2 & A2B1 gametes come from and what determines their frequencies? B1 A2 B2 A1 B2 A2 B1 from meioses with no recombina+on between A and B loci from meioses with recombina+on between A and B loci What determines the frequencies of A1B2 and A2B1 gametes from this genotype? Level of Gene+c Linkage between A the B loci What will be their frequencies if A and B are on diﬀerent chromosomes? Frequencies will be 0.25 for each gamete type: A1B1 A1B2 A2B1 A2B2 Linkage = 0, this is the maximum produc+on of new types. What will be their frequencies if A and B are closely linked on a chromosome? Frequencies of new, recombinant haplotypes will be low or maybe even zero. 4 Maximum A1 A2 LD B1 B2 A2 Linkage Disequilibrium is high in Humans
GAMETES A1 B1 perfect correla+on of Single Nucleo+de Polymorphisms (SNPS) at paired sites
B2 A1 Par+al LD Fig 9.15 index of LD B1 A1 B1 A2 B2 A2 B2 A2 B2 A1 approach to equilibrium frequencies A2 B2 A1 B1 A2 B2 A1 B2 A2 B1 no correla+on of SNPS...
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 Spring '10
 Reinthal
 Equilibrium, Evolution, Genetic linkage, A100, linkage disequilibrium, B100, A200

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