chap_21-1

Chap_21-1 - 4 No migration into or out of the population 5 No genotype-dependent differences in survivability(i.e and ability to transmit genes

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Chapter 21, Part I Population Genetics The CDC (Centers for Disease Control and Prevention) recently identified a novel genetic disease. They want to know the extent to which the disease will spread throughout the United States. How would they go about doing that? = Hardy-Weinberg Law Can describe the inheritance of alleles in a population
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Frequencies associated with the Hardy- Weinberg law Phenotype frequency proportion of individuals who express a particular trait Genotype frequency proportion of individuals who carry a particular genotype Allele frequency proportion of all copies of a gene of a given type
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Frequency examples 3 people in a small population of 12 have cystic fibrosis Frequency = 6 of the 12 people are “carriers” Frequency = Frequency of the cystic fibrosis allele =
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What assumptions about the population being studied are necessary to achieve Hardy-Weinberg equilibrium? 1. Infinite (or very large) population 2. Individuals mate at random 3. No new mutations appear
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Unformatted text preview: 4. No migration into or out of the population 5. No genotype-dependent differences in survivability (i.e. and ability to transmit genes) Sample population (10 individuals): Aa AA AA aa AA AA Aa AA AA AA # of A alleles = # of a alleles = Review Let p = frequency of A in population. Let q = frequency of a in population. p = 16/20 = 0.8 q = 4/20 = 0.2 = frequency of A gametes in population = frequency of a gametes in population Note: p + q = 1 . .. p = 1 - q, and q = 1- p If know one, can calculate other! Expected frequencies of genotypes in large, random mating population p 2 + 2 pq + q 2 = 1 0.8 0.8 0.2 0.2 Expect: AA = p 2 = Aa = 2pq = aa = q 2 = Phenyl thiocarbamide (PTC) taster activity How many people are PTC taster heterozygotes in our classroom population? How do we figure this out? p + q = 1 (allele frequencies) p 2 + 2 pq + q 2 = 1 (genotype frequencies) # of tasters = # of non-tasters = # of students in ‘population’ =...
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This note was uploaded on 02/03/2011 for the course BIOL 2153 taught by Professor Larkin during the Fall '03 term at LSU.

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Chap_21-1 - 4 No migration into or out of the population 5 No genotype-dependent differences in survivability(i.e and ability to transmit genes

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