BIOL 1107 1nd Edition Lecture 33Outline of Last Lecture I. Population ChangeII. Thomas Malthus & Carrying CapacityIII. Passenger Pigeon & Indigenous BirdsOutline of Current Lecture I. Gene Pool II. Allele FrequencyIII. ExamplesCurrent LectureI. Gene Pool - Gene Pool- set of all genes, or genetic information, in any population, usually of a particular species.o Proves to be the basic level at which evolution occurs o A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive bouts of intense selection - Low genetic diversity can cause reduced biological fitness and an increased change of extinction, although as explained by genetic drift new genetic variants, that may cause an increase in the fitness of organisms, are more likely to fix in the population if it is rather small II. Allele Frequency- Allele frequency- how often that gene is seen in the population - Q: Dominant alleles occur more frequently in a population than recessive alleles o A: False, just because gene is dominant doesn’t mean it is more frequent - Calculating Allele Frequency:- Q: What is the frequency of the M allele?These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Blood type NumberM 285N 225MN 490- A: 0.53- MM = 285 + 285 + 490 = (1060/2000) = 0.53 (MM because each person has two alleles)- N = 0.47 - 0.53 + 0.47 = 1.00III. Examples - Flower Color in Pea Plants - Q: What is the frequency of the P allele?Flower color NumberPurple 750White 2501000- White flowers -> homozygous recessive - Hardy-Weinberg equation: - Q: a population has a gene with two alleles, A and a. The frequency of A = 60% and of a = 40% - The frequency of the genotype should be: o AA: 0.86 -> 0.6 X 0.6o Aa: 0.48 -> 2 X 0.6 X 0.4o Aa: 0.16 -> 0.4 X 0.4- So what?- An allele for the gene CCR5-, is believed to confer resistance to HIV when homozygous - Q: If the frequency of the CCRD- allele is 10%. What proportion of the population would you expect to be resistant to HIV?- A: 0.1 X 0.1 = 0.01 -> 1% resistant to HIV - Individuals that are heterozygous for CCR5- may have partial resistance to HIV- Q: If the 4% of a population is homozygous recessive for CCR5-, what % would you expect to be heterozygous? - A: 2pq -> 2 x 0.8 x 0.2 = 0.32 -> 32%o q^2 = 0.04o q = 0.2- Hardy-Weinberg equilibrium:o M = p = 0.53 o N = q = 0.47 MM MN NNObserved 285/1000 490/1000 225/1000Expected (p^2) = 0.63 x 0.63 2 x 0.63 x 0.47 0.47 x 0.4728.1% 49.8% 22.09%- Q: You observe the following population: Genotype NumberAA 800Aa 100Aa 100Total: 1000- p = 0.85 (800 + 800+ 100)/ (2000)- q = 0.15 - p^2 = 0.722 = 72.2%- q^2 = 0.0225 = 22.5%- 2pq = 0.265 = 26.5%- Is this population in Hardy-Weinberg equilibrium?o (1) Yes (2) No- When Hardy-Weinberg is not at equilibrium, population is
View Full Document
Unlocking...