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Lecture notes - January 22

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BIOL 1500
Alexander Mills

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Biology Lecture January 22, 2014  ABO System: 2 alleles Co dominance:  A is codominant to B  A and B are dominant to O  O is recessive Evolution: change in allele frequency of a population over time - Two genes are in every locus Hardy-Weinberg Theorem: 1908  Presented independently by both  Theorem: frequencies of alleles and genotypes in a population’s gene pool remain constant from generation to generation if the only process at work is meiosis  Describes population that is not evolving Question: In a population in HW equilibrium, the frequency of allele A1 is 1/3 and that of allele A2 is 2/3. What is the frequency of the A1/A1 genotype in the population? Answer: 1/9 - 1/3 * 1/3 = 1/9 The Product Rule for Probabilities  The probability of two things happening is the product of their independent probabilities HW Equilibrium  P + q = 1  P^2 + 2pq + q^2 = 1  Null hypothesis for “no evolution” because evolution is a change in a population’s allele frequencies between generations H-W Equilibrium requires 5 conditions to be met: *****IMPORTANT****** 1. No natural selection is occurring 2. No genetic drift is occurring: change in alleles in a population due to random factors due to population decreasing 3. No gene flow is occurring – migration: ancestors from diff. parts of the world – bring genes from other parts of the world 4. No mutation is occurring 5. Mating among individuals in the population is random LECTURE: January 24, 2014 4 mechanisms of evolutionary change: 1. Natural Selection 2. Genetic drift 3. Gene flow 4. Mutation 5. Non-random mating Human MN blood group system  Two alleles code for a 2 versions of a protein on the surface of red blood cells Question: For 2 alleles (M & N) in a co-dominant system, how many genotypes and phenotypes are there? Answer: 3 genotypes and 3 phenotypes LECTURE: January 29, 2014 Question 1: Carbon 11 is a rare isotope with a half-life of 20 mins. It is not of any help in reconstructing the long ago past! It decays into Boron-11 which is stable. You are given a sample that you are advised was pure Carbon-11 but which now contains a mix of Carbon-11 and Boron-11. In fact the sampele is 6 1.4 % Carbon 11 with the balance being boron-11. How long ago was the sample pure carbon 11? Question 2: What are the frequencies of the F and f alleles in the population? F allele in sperm F allele in sperm F allele
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