GCD 3022K Conklin Lecture 40 Outline of Last Lecture I Genetic drif a Population size b Bottleneck effect II Hardy Weinberg Equilibrium a PTC Example b Tongue Rolling Example c Sheep Example III Inbreeding a Allele and genotype frequencies b Rare recessive genetic diseases Outline of Current Lecture I Inheritance a Inbreeding b Monomorphic vs Polymorphic c Hemophilia example II Hardy Weinberg equilibrium a 2pq b Example c Rabbit example III Microevolution a Genetic drif b Mutation and mutation rate c Natural Selection d Migration e Nonrandom mating Current Lecture I Inheritance a Inbreeding increases the proportion of homozygous individuals in a population These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute II III b Monomorphic vs Polymorphic monomorphic allele is one that accounts for at least 99 of all alleles for a given gene A polymorphic allele is one of at least two that exist for a given gene c Hemophilia example in humans Hemophilia A is a recessive X linked trait and the allele frequency of Hemophilia A is 1 and 10 000 0 0001 The other allele for this gene is the wild type allele Males can be affected or unaffected but females can be affected unaffected carriers or unaffected homozygous for wild type i Allele frequencies of mutant and wild type alleles in human population Frequency of mutant allele 0 0001 q 1 q p p 0 9999 ii Among males the frequency of affected individuals is 0 0001 because males only need to inherit one copy of the mutant X chromosome to be affected This number is equal to the frequency of the allele in the population Hardy Weinberg equilibrium most natural populations are not in Hardy Weinberg equilibrium a 2pq represents the frequency of all heterozygotes b Example a population that is 36 homozygous recessive for a given gene means that i The frequency of allele a in the population is sq rt of 0 36 0 6 ii Frequency of allele A is 1 0 6 0 4 iii Frequency of Aa genotype 2 0 6 0 4 0 48 c Rabbit example population of 6 340 rabbits and 450 have short toes recessive trait Population is assumed to be in Hardy Weinberg equilibrium i Frequency of short toes tt q2 450 6340 0 071 The square root of this number is q which is 0 266 the frequency of the t allele ii Frequency of long toe allele T 1 0 266 0 734 iii Number of rabbits that are heterozygous and carry t allele 2pq 0 39 39 of population 0 39 6340 2472 animals that are heterozygous Microevolution a Genetic drif change in genetic variation from generation to generation due to random sampling error Has a greater effect on small populations Can involve the bottleneck or founder effect A possible outcome of genetic drif is allele fixation b Mutation and mutation rate changes in DNA sequence that result in phenotypic change Have a very small effect on changing allele frequencies in both large and small populations c Natural Selection the environment selects for individuals that favor survival and reproductive success This can result in changes in allele frequency of large and small populations d Migration introduction of new alleles into a population by gene flow This can change allele frequency if the influx of migrants is large compared to the recipient population or if the recipient population is small e Nonrandom mating individuals select mates based on phenotype or genetic lineage This can change the relative proportion of homozygotes and heterozygotes but does not change the allele frequencies in large or small populations
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