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Pop gen part 2new
Pop gen part 2new
Pop gen part 2new
Pop gen part 2new
Pop gen part 2new
Pop gen part 2new
Pop gen part 2new
Pop gen part 2new
Pop gen part 2new
Pop gen part 2new
Pop gen part 2new
Pop gen part 2new
Pop gen part 2new
Pop gen part 2new
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Pop gen part 2new

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  • 1.  
  • 2. 14.2 Hardy-Weinberg Law
  • 3. Concept review… Population genetic Gene pool concept Hardy-Weinberg Law
  • 4. At the end of the lesson, you should be able to : <ul><li>a) Hardy-Weinberg law </li></ul><ul><li>State the Hardy-Weinberg law </li></ul><ul><li>Explain five assumptions of Hardy –Weinberg Law for genetic equilibrium: </li></ul><ul><li>Large population size </li></ul><ul><li>Random fertilization </li></ul><ul><li>no net mutation </li></ul><ul><li>no migration (include genetic drift) </li></ul><ul><li>no natural selection </li></ul><ul><li>b) Calculate allele and genotype frequencies </li></ul>
  • 5. The Hardy-Weinberg equilibrium <ul><li>In 1908, G. H. Hardy (an English mathemathician) &amp; W. Weinberg (a German physician) independently identified a mathematical relationship between alleles and genotypes in </li></ul><ul><li>populations. </li></ul><ul><li>This relationship has been called the Hardy-Weinberg equilibrium and it concerns allele frequency </li></ul>
  • 6. Hardy-Weinberg Law <ul><li>The principle that frequencies of alleles and genotypes in a population remain constant from generation to generation , </li></ul>
  • 7. Hardy-Weinberg Law <ul><li>Condition of a population for Hardy-Weinberg equilibrium </li></ul><ul><ul><li>very large population size so that genetic drift can be avoided (chance fluctuation in the gene that can cause phenotype frequencies to change over time). </li></ul></ul><ul><ul><li>no migration that cause gene flow due to immigration into or emigration out from the population </li></ul></ul>
  • 8. <ul><ul><li>no net mutations because mutation may change an allele into another &amp; this changes allele frequencies </li></ul></ul><ul><ul><li>random fertilization because if individuals choose mates only with certain traits, frequencies of certain alleles may change </li></ul></ul><ul><ul><li>All individuals must be equally fertile and able to pass the alleles to the next generation so that no natural selection is taking place </li></ul></ul>
  • 9. Hardy-Weinberg Law. <ul><li>Related to allele frequencies are the genotypic frequencies </li></ul><ul><li>Genotype frequency is the ratio of number of individuals with certain genotype in a population </li></ul><ul><li>Hardy-Weinberg equations are used to estimate the frequencies of alleles &amp; genotypes in a population which is in genetic equilibrium </li></ul>Hardy-Weinberg Equations
  • 10. Hardy-Weinberg Law. <ul><li>The equations: </li></ul><ul><li>p 2 + 2 pq + q 2 = 1 and p + q = 1 </li></ul><ul><li>p 2 = genotypic frequency of homozygous dominant </li></ul><ul><li>2pq = genotypic frequency of heterozygous </li></ul><ul><li>q 2 = genotypic frequency of homozygous recessive </li></ul><ul><li>p = frequency of dominant allele </li></ul><ul><li>q = frequency of recessive allele </li></ul>Hardy-Weinberg Equations
  • 11. Hardy-Weinberg Law. <ul><li>Question 1 </li></ul><ul><li>Resistance toward a type of pesticide for a population of rats is controlled by dominant allele, R. 64% of the rat population show the resistance. </li></ul><ul><li>a) Calculate the frequency for R allele. </li></ul><ul><li>Assume that the population is in genetic equilibrium and </li></ul><ul><li>p 2 + 2pq + q 2 = 1 while p + q = 1 </li></ul><ul><li>36% of rat population are homozygous recessive (rr). </li></ul><ul><li>Genotypic frequency for homozygous recessive (rr), q 2 = 0.36 </li></ul><ul><li>Frequency for recessive allele (r), q = √0.36 </li></ul><ul><li>= 0.6 </li></ul><ul><li>Frequency for dominant allele (R), p = 1 - q </li></ul><ul><li>= 1 – 0.6 </li></ul><ul><li>= 0.4 </li></ul>Example of calculation
  • 12. Hardy-Weinberg Law. <ul><li>b) Calculate the number of rats with genotypes RR, Rr and rr for a population of 200 rats. </li></ul><ul><li>It is already known that p = 0.4 and q = 0.6 </li></ul><ul><li>Genotypic frequency for homozygous dominant (RR), p 2 = (0.4) 2 </li></ul><ul><li> = 0.16 </li></ul><ul><li>Number of rats with genotype RR = 0.16 x 200 </li></ul><ul><li>= 32 </li></ul><ul><li>Genotypic frequency for heterozygous (Rr), 2pq = 2(0.4)(0.6) </li></ul><ul><li> = 0.48 </li></ul><ul><li>Number of rats with genotype Rr = 0.48 x 200 </li></ul><ul><li>= 96 </li></ul><ul><li>Genotypic frequency for homozygous recessive (rr), q 2 = 0.36 </li></ul><ul><li>Number of rats with genotype rr = 0.36 x 200 </li></ul><ul><li>= 72 </li></ul>Example of calculation
  • 13. Hardy-Weinberg Law. <ul><li>Question 2 </li></ul><ul><li>For a population of Shorthorns, the following data was obtained: </li></ul><ul><li>Calculate the frequencies for alleles C M and C P . </li></ul><ul><li>Total number of individuals for the population = 308 </li></ul><ul><li>Frequency for allele C M = 2(110) + 150 </li></ul><ul><li> 2(308) </li></ul><ul><li>= 0.6 </li></ul><ul><li>Frequency for allele C P = 2(48) + 150 </li></ul><ul><li> 2(308) </li></ul><ul><li>= 0.4 </li></ul>Examples of calculation Genotype Phenotype Number of individuals C M C M red 110 C M C P red &amp; white 150 C P C P white 48
  • 14. Sekilas pandang… Thank you for your attention

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