Chapter 24

Chapter 24 - Please, Turn Your Cell Phones OFF Now. Thanks!...

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Please, Turn Your Cell Phones OFF Now. Thanks!
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Which of the following is NOT an assumption of Hardy-Weinberg? A. genetic drift is insignificant B. mating is non-random C. no mutations are occurring D. there is no gene flow E. none of the above (A.-D. are all assumptions of the H-W model)
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KEY CONCEPTS The Hardy-Weinberg principle acts as a null hypothesis when researchers want to test whether evolution or nonrandom mating is occurring at a particular gene.
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Please, Turn Your Cell Phones OFF Now. Thanks!
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Analyzing Change in Allele Frequencies: The Hardy- Weinberg Principle
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G. H. Hardy and Wilhelm Weinberg independently developed a mathematical model to calculate what happens to allele frequencies when no evolution is taking place .
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Analyzing Allele Frequency Change: The Hardy-Weinberg Principal Analyzes what happens to the frequencies of two alleles at a single locus when NO evolutionary forces are acting on a population. This model has been tested and verified many times in the lab and field. H-W model provides a baseline against which to judge whether or not the population is evolving.
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Hardy-Weinberg Equation p 2 + 2 p q + q 2 = 1 p + q = 1 p = frequency of allele 1 in population q = frequency of allele 2 in population
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(1) NO selection, (2) NO genetic drift, (3) NO gene flow (migration), (4) NO mutation, and (5) RANDOM mating The Hardy-Weinberg model applies under the following important assumptions:
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The Hardy-Weinberg principle serves as a “null hypothesis” for determining whether evolution is acting on a particular gene in a population.
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How Does the Hardy-Weinberg Principle Serve as a Null Hypothesis?
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Geneticists can estimate the frequency of each genotype in a population. obtain genotype data from a large number of individuals, then divide the number of individuals with each genotype by the total number of individuals in the sample.
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When genotype frequencies (single gene, two alleles) do not conform to H- W proportions, either evolution is occurring in that population, or mating is not random.
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If only phenotype data are available, it is not always possible to estimate genotype frequencies. Sometimes, however, genotypes can be estimated by assuming that H-W is true. I.e., assume the phenotype is determined by a single gene with two alleles , and that particular gene is not evolving .
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Earlobe Attachment Free Attached
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My earlobes are ___________. A. Free (unattached) B. Attached
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Earlobe Attachment Free (Dominant) Attached (Recessive)
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Earlobe Phenotype Number Frequency Free 151 .78 Attached 43 .22 Total 194
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Earlobe Genotype Number Frequency AA ?? .61 Aa ?? .3432 aa .048
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left-handed (rr). Assume that handedness is not subjected to any evolutionary mechanism and that mutation is negligible. What is the frequency of right-handed homozygotes (RR) in the class? A. 0.91
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This note was uploaded on 04/07/2008 for the course BIOL 100 taught by Professor Staff during the Fall '07 term at UMBC.

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Chapter 24 - Please, Turn Your Cell Phones OFF Now. Thanks!...

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