# Bio115 - Lecture 35

 Genomic screening for newborns Screening for large number of genetic diseasesBetter/earlier preventative treatement Genomic screening for personalized medicine Able to predict responses to different treatments and fine-tune drug therapy for individualGenetic testing of both patients and pathogens will allow faster and more precise diagnosis of many diseases What is population genetics? The study of the genetic makeup of groups of individuals and how a group’s genetic composition changes with time What are Mendelian populations? Groups of interbreeding sexually reproducing individuals that share the same gene pool. What is a gene pool? A common set of genes in a population Population geneticists study: The variation in alleles within and between groupsThe evolutionary forces that shape patterns of genetic variation What causes phenotypic varation within a population? Genotypic variation Genotypic frequency: f(AA) f(AA) = (number of AA individuals)/N, where N is the number of individuals in the sample Calculating the frequency of an allele freq of an allele = (# of copies of allele)/(# of copies of alleles at the locus) Allele frequency: p = f(A) f(A) = (2nAA + nAa)/(2N) Calculate allelic frequencies from individual frequencies p = f(A) = f(AA) + (1/2)f(Aa) Calculate allelic frequencies at loci with three alleles p = f(A1) = (2nA1A1 + nA1A2 + nA1A3)/2N Calculate allelic frequencies from individual frequencies with three alleles p = f(A1A1) + (1/2)f(A1A2) + (1/2)f(A1A3) Calculate allelic frequencies at X-linked loci p = f(XA) = (2nXAXA + nXAXa + nXAY)/(2nfemales + nmales) Calculate allelic freq's at X-linked loci from individual frequencies p = f(XA) = f(XAXA) + (1/2)f(XAXa) + f(XAY) Study example on slide 15 human MN blood-type antigens What assumptions does the Hardy-Weinberg law make? The population is large, randomly mating, and not affected by mutation, migration, or natural selection The Hardy-Weinberg Law predictions: Prediction 1: The allelic frequencies of a population do not changePrediction 2: The genotypic frequencies stabilize (do not change) after one generation in the following proportions: p^2, 2pq, q^2The allelic frequencies determine the frequencies of genotypes If a population meets the Hardy-Weinberg assumptions, can it evolve? Yes, but it requires external pressure. When a population is in Hardy-Weinberg equilibrium, the genotypic frequencies are determined by ... the allelic frequencies Authorlukemlj ID52169 Card SetBio115 - Lecture 35 DescriptionBio115 Lecture 35 Updated2010-12-01T08:06:17Z Show Answers