Pop gen part 1


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Pop gen part 1

  1. 2. Chapter 3 Population Genetic
  2. 3. Concept review… Population genetic Gene pool concept Hardy-Weinberg Law
  3. 4. At the end of the lesson, you should be able to : <ul><li>a)Gene pool concept: </li></ul><ul><li>Explain gene pool and allele frequency </li></ul><ul><li>Explain population genetics and its relation to allele frequency </li></ul><ul><li>Explain allele frequency and genetic equilibrium </li></ul>
  4. 5. Gene pool concept
  5. 6. Gene pool concept <ul><li>Studies the change of frequencies of alleles within a population </li></ul><ul><li>Population :- a group of individuals of the same species that live in a habitat & may interbreed to produce fertile offspring </li></ul><ul><li> - shares a same gene pool </li></ul><ul><li>Gene pool - total aggregate of genes in a population at any one time </li></ul><ul><li> - consists of all alleles at all gene loci in all individuals of the population at a given time </li></ul>
  6. 7. Gene pool concept <ul><li>For a diploid species, each locus is represented twice in the genome (homozygous / heterozygous) </li></ul><ul><li>Eg: - A study was done on 10,000 rats, focusing on the fur colour (determined by dominant allele A & recessive allele a) </li></ul><ul><li>- Data: AA individuals = 6,000 </li></ul><ul><li>Aa individuals = 2,000 aa individuals = 2,000 </li></ul><ul><li>:. Total number of alleles for fur colour = 2(6000) + 2(2000) + 2(2000) </li></ul><ul><li> = 20000 </li></ul>
  7. 8. Gene pool concept <ul><li>Each of the allele types has a relative frequency in the gene pool </li></ul><ul><li>Allele frequency : ratio of any given allele in a population, relative to all the other alleles of that gene at the same locus </li></ul><ul><li>Eg: - Using the previous data, calculate the allele frequencies for A & a in the gene pool </li></ul><ul><li>- Total of A alleles = 2(6000) + 1(2000) = 14000 </li></ul><ul><li>- Total of a alleles = 2(2000) + 1(2000) = 6000 </li></ul><ul><li>- Frequency for A alleles = 14000 / 20000 = 0.7 </li></ul><ul><li>- Frequency for a alleles = 6000 / 20000 = 0.3 </li></ul>
  8. 9. Gene pool concept <ul><li>For a gene locus where only 2 alleles occur in a population, allele frequencies can be calculated using this equation : </li></ul><ul><li> p + q = 1 </li></ul><ul><li>p = frequency of the dominant allele </li></ul><ul><li>q = frequency of the recessive allele </li></ul><ul><li>If q = 0.3, p = 1 – 0.3 = 0.7 </li></ul>
  9. 10. Gene pool concept <ul><li>Allele frequencies in a gene pool determine the genetic change for a population </li></ul><ul><li>Naturally, the composition of a gene pool may change over time due to certain factors </li></ul><ul><li>Change in allele frequencies </li></ul><ul><li>Change in gene pool </li></ul><ul><li>Change in genetic composition of population </li></ul><ul><li>Evolution </li></ul>
  10. 11. Gene pool concept <ul><li>If no change in allele frequencies from one generation to the next, the gene pool is considered static </li></ul><ul><li>This shows that the gene pool is in genetic equilibrium </li></ul>
  11. 12. Sekilas pandang… “ Hiduplah dengan penuh cita-cita & harapan, jadilah manusia yang sentiasa berpandangan jauh dan berwawasan…”
  12. 13. Sekilas pandang… Thank you for your attention