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Monday, September 10, 2012

Monday, September 10, 2012. Purpose of H-W Principle:. The Hardy-Weinberg Principle provides a baseline for comparison & determines whether or not gene frequencies have changed in a population and thus whether (micro)evolution has occurred. Hardy-Weinberg Assumptions.

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Monday, September 10, 2012

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  1. Monday, September 10, 2012

  2. Purpose of H-W Principle: The Hardy-Weinberg Principle provides a baseline for comparison & determines whether or not gene frequencies have changed in a population and thus whether (micro)evolution has occurred.

  3. Hardy-Weinberg Assumptions • Very large population size • No migration • No net mutation • Random Mating • No natural selection

  4. Hardy-Weinberg Equations: p = frequency of allele 1 in gene pool q = frequency of allele 2 allele in gene pool Frequencies can be expressed as decimals (0.4) or percentages (40%) p + q = 1

  5. Hardy-Weinberg Equations: Allele frequency is used to predict genotype frequency (%) for a randomly mating population Homozygous for allele 1 = p • p = p2 Homozygous for allele 2= q • q = q2 Heterozygous = p • qorq • p = 2pq p2 + 2pq + q2 = 1

  6. Hardy-Weinberg Lab • Instructions dictate initial allele frequencies of: • p = 0.5 • q = 0.5 • If there are 28 Teddy Grahams in your population, how many should be pp? pq? qq? • Explain how you determined your answer.

  7. Teddy Grahams mate randomly. All bears areequally attractive.

  8. Though they live a good life, it is short. After having 2 babies, they die keeping the population size constant .

  9. All bears are equally in danger of predation due to their yumminess

  10. Teddy Graham Genetics • Today you will be helping Teddy Grahams to procreate. • Reminder of the genetic rules: • When honey and honey mate, 2 Honey are born • When honey and chocolate mate, 2 speckled are born • When honey and speckled mate, One honey and one speckled are born • When chocolate and speckled mate, One chocolate and one speckled are born

  11. When Speckled and Speckled mate • Use the allele cards. Each speckled has a p and a q allele • Pick one allele for each parent to give • This determines the genes of the first offspring • Return the cards to the parent and pick again for the second offspring

  12. Allow 5 generations to mate. • Fill in the data chart and calculate allele frequencies at the end of 5 generations • Conduct a Chi Square test to see whether the number of bears of each type you expect to have if allele frequencies did not change, differs from the observed (actual) number of each type you have

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