Biology 1001A Study Guide - Final Guide: Genotype Frequency, Allele Frequency, Heterozygote Advantage

39 views12 pages

tantermite285

29 Sep 2017

School

Western University

Department

Biology

Course

Biology 1001A

Professor

Beth Mac Dougall- Shackleton

For unlimited access to Study Guides, a Grade+ subscription is required.

Document Summary

Lectures #13-23, lab & literacy outcomes; november 27th, 2014. Conditions necessary for hardy-weinberg equilibrium: large, random-mating population -> to avoid genetic drift, no natural selection -> allele frequencies do not change over time, no gene flow (no migration, mutations are very rare, trait is selectively neutral. Genotype frequencies in the next generation, given the allele frequencies and assuming hardy- Weinberg equilibrium f(a1a1)= p2 f(a1a2)= 2pq f(a2a2)= q2. Whether a population is in hwe, given observed genotype or phenotype frequencies: ex. Effect of heterozygote advantage on genetic variation: heterozygote advantage occurs when heterozygotes have the highest fitness. Difference between positive and negative frequency-dependent selection, and how each affects genetic variation & how positive and negative frequency-dependent selection affect genetic variation: positive frequency-dependent selection (rare) = rare genotypes not favoured, ex. Predators learn to detect warning colouration -> avoid common (poisonous) phenotypes: reduces genetic variation, negative frequency-dependent selection = common phenotypes not favoured, ex.

Related Questions

I need this in 15 min!Please help!!!1

A gene in a population of sexually reproducing organisms with the following genotype frequencies is at Hardy-Weinberg Equilibrium: BB 100, Bb 800, bb 100

A) true B)false C) can not be determined

Which of the following evolutionary forces would be the best explanation for the genotype frequencies in the population in the above question?

A) genetic drift B) there are no evolutionary forces acting on this gene population C)assortive mating D) Overdominance E)Directional selection

If a population is at Hardy-Weinberg equilibrium, which of the following allele frequencies would yield the smallest number of heterozygotes? A)

A=0.25, B=0.75 B) A=0.75, B=0.25

C)A=0.50, B=0.50

D)A=0.10, B=0.90

Fixation occurs when one allele becomes the only allele for a gene in a population, meaning that all other alleles for that gene have been lost. True or false

azurepug898

Q1. What are alleles?Different forms of the same gene.Different genes.The different characteristics of an organism.Genes found only in humans.Q2. If you add up the frequency of homozygotes + the frequency of heterozygotes for one gene (i.e. at one locus) in a population, what number do you get?Q3. People who are heterozygous for the sickle-cell allele:Are susceptible to malaria but not sickle-cell anemia.Are susceptible to sickle-cell anemia but not malaria.Are not susceptible to either sickle-cell anemia or malaria.Are susceptible to both sickle-cecell anemia and malaria.Q4. In the case study in this lab, which genotype is represented by "2pq" in the Hardy-Weinberg equation?Homozygous HbAHomozygous HbSHeterozygous HbA/HbSNo specific genotypeQ5. Suppose that, in an isolated village, the proportion of individuals that have sickle-cell anemia is 0.1 (or 1 of every 10 people). What proportion of the population should be sickle-cell carriers, according to Hardy-Weinberg expectations?Q6. When you simulated the elimination of malaria at the beginning of the lab, once the allele frequencies stabilized, what was the frequency of the HbA allele?Q7. When you investigated regional differences, what was the frequency (over many generations) of the HbS allele in the village in the "slightly wet" part of Africa?Q8. What is the number of deaths due to sickle-cell anemia in a region without mosquitoes expected to be?Very lowVery highModerateRelated to the frequency of malaria allelesQ9. As long as there are multiple alleles of a gene in a population, why will the frequencies of the alleles always change over time?Because natural selection changes all allele frequencies in populations over time.Because genetic drift causes random fluctuations of allele frequencies in populations.Because diseases will eliminate some of the alleles, generating fluctuations in their frequencies.Because allele frequencies fluctuate before the alleles eventually become fixed.Q10. Imagine a huge population with a gene that has ten functionally equivalent, neutral alleles. A small but genetically representative group of individuals from the big population is transported to an island, forming a small population. Which of the statements below best describes what will likely happen over time, and why?Because natural selection doesn't act on neutral alleles, the frequencies in the two populations should remain the same over time.Genetic drift will cause one allele to first become fixed in the island population, and later to become fixed in the original, large population.Genetic drift will result in the allele frequencies of the two populations diverging over time, with alleles being lost sooner in the island population.The allele frequencies of the two populations will change similarly due to a combination of genetic drift natural selection.

indigosnake469

Cats have recently migrated from Malaysia to an uninhabited island in the South China Sea. The gene pool of the migrants includes both alleles for straight (T) and stub (t) tails. You study selection pressures on these cats in the wild, finding the following survivorship in a cohort of 650 kittens.

Phenotype	Straight	Bent	Stub
Genotype	TT	Tt	tt
Number of Kittens	100	250	300
Surviving adults	70	161	126

a) Calculate survivorship and relative fitness for each genotype

b) Calculate the selection coefficient (s) and degree of dominance (h)

c) Is the population of kittens in Hardy-Weinberg Equilibrium? [Assume that freq. (T) = p and freq. (t) = q].

d) Calculate the average fitness of the population of kittens and of the population of adults.

e) Calculate allele frequencies before (kittens) and after (adults) selection in the next generation. [Assume that freq. (T) = p and freq. (t) = q].

f) Which of the two alleles is deleterious? Justify your answer.

Biology 1001A Study Guide - Final Guide: Genotype Frequency, Allele Frequency, Heterozygote Advantage

Document Summary

Get access

Related Documents

Biology 1001A Final: Second Term Outcomes

Biology 1001A Study Guide - Final Guide: Genotype Frequency, Allele Frequency, Frequency-Dependent Selection

Biology 1001A Lecture Notes - Lecture 1: Symplesiomorphy, Fetus, Mutation

Related Questions