BI226 Lecture Notes - Lecture 12: Genotype Frequency, Allele Frequency, Population Genetics
Document Summary
Random mating: random mating produces genotype frequencies that can be predicted through allele frequencies. Chi-square test of h-w predictions: helps determine how different observed genotype frequencies are from predicted h-w frequencies, can show significant difference. Natural selection and fitness: allele frequencies change when evolution occurs. If the heterozygous genotype is favoured, genetic diversity is maintained: balanced polymorphism: allele frequencies are maintained, relative intensity of natural selection, pe= t/(s+t, qe= s/(s+t, s and t are the relative fitness values for the homozygous states. Ccr5 gene encodes protein c-c chemokine 5: signalling molecules in the immune system, mutant form is ccr5 delta 32 (32 bp deletion, hiv binds to this cell to gain entry. Individuals heterozygous (one wild type allele, one mutant allele) are susceptible to hiv but show prolonged progression. Individuals homozygous for the mutant are resistant to hiv: the mutant is typically found in europeans, this is because small pox and plague used ccr5 to enter cells too, so.
