BIOL 2081C Lecture Notes - Lecture 32: Zygosity, Allele Frequency, Genotype Frequency

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jadecattle874

19 Sep 2017

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Department

Biological Sciences

Course

BIOL 2081C

Professor

Uhl Juli

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Document Summary

Learning objectives: describe the four processes that account for most changes in allelic frequency in a population. **answered in lecture 31 lo"s*: model how random mating yields predicted genotype frequencies in hardy-weinberg. Equilibrium (hwe), and how non-random mating affects allele and genotype frequencies: test whether hardy-weinberg equilibrium (hwe) has been reached in a population. Pre-class assignment: complete the genetic drift simulation here, then answer the five question quiz after viewing the video, complete the analysis and application problems 17. 2, 17. 4, 17. 11, and 17. 6 (hint for. Extension of hw to x-linked recessive alleles: frequency of affected males = q, ex: as many as 8 in 100 men are colorblind due to a recessive allele affecting photoreceptor function. A pedigree showing inbreeding: figure 17. 19: (a) an inbreeding pedigree in which individual i results from a mating between half siblings. (b) the same pedigree redrawn to show gametes in the closed loop leading to individual i.

Related Questions

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.

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Indicate the effect of this condition of the Hardy-Weinbergprinciple on genotype and allele frequencies: assortativemating
a.alters genotype and allele frequencies
b.alters genotype only
c.alters allele frequency only
d.does not alter genotype or allele frequency

Polydactylism (possessing more than five fingers per hand) withinthe Amish population in Pennsylvania is considered an example offounder effect. This is because the frequency of polydactylismamong the Amish in Pennsylvania is identical to its frequency amongthe Amish population in Germany.
a.true.
b.false

A population of bacteria is in Hardy-Weinberg equilibrium. However,through repeated exposure to an antibiotic, the frequency of therecessive allele is rapidly increasing. What is the most likelyexplanation for this response? The recessive allele is responsiblefor susceptibility of the bacteria to the antibiotic.
a.The dominant allele is responsible for susceptibility of thebacteria to the antibiotic.
b.The recessive allele is responsible for resistance of thebacteria to the antibiotic.
c.The population is experiencing gene flow.
d.The population is experiencing disruptive selection.

Biotic environments that influence natural selection includes allbut which of the following?
a.competition
b.predation
c.parasitism
d.weather
e.disease

Why does the malaria disease persist in the human population?
a.Too few humans have died of malaria to end the disease.
b.Multiple phenotypes survive in a balanced polymorphism.
c.Malaria is a recessive disease and few humans are eversick.
d.Humans are protected from the malaria parasite.
e.The disease is under stabilizing selection.

In random mating,;

A.individuals choose the most attractive mate.
B.there is no influence on mate choice.
C.breeding occurs between two different species.
D.breeding occurs between two different subspecies.
E.fertile offspring are not produced.

A fraction of the original green frog population survives toreproduce and generate the new population. If the survivors of theoriginal population survived by chance, then this event is anexample of
A.natural selection.
B.genetic drift.
C.founder effect.
D.industrial melanism.

Which of the following is most likely an example of a foundereffect event?
A.A random small group of a bird population migrates to an islandand then returns to breed.

B.A random large group of a bird population migrates to an islandand then returns to breed.

C.A selected small group of a bird population migrates to an islandand then returns to breed.

D.A random small group of a bird population migrates to an islandand does not return to breed.

E.A random large group of a bird population migrates to an islandand does not return to breed.

Microevolution is not influenced by which of the following?

A.mutation
B.random mating
C.gene flow
D.natural selection
E.genetic drift

In a large population of an annual wild pea species, height is controlled by a single locus; DD and Dd individuals are tall, while dd individuals are short. Because the local environment is very windy, tall plants tend to get broken and survive to reproduce only half as well as well as do short plants. Mating is random with respect to height and there is no immigration or emigration. In a population of 21,000 (large enough to be considered infinite for the purposed of the Hardy-Weinberg equilibrium and natural selection models; assume this population size remains constant through the generations described in this question) adult pea plants that successfully reproduce after natural selection through differential survival has occurred, there are 7,000 DD individuals, 7,000 Dd individuals, and 7,000 dd individuals.

a) What will be the frequency of the D allele in the gametes (sperm, in pollen, and ovules) that will unite to make up the next generation?

b) What will be the genotype frequencies of DD, Dd, and dd in the seeds that are formed to start the next generation? How many seeds will there be with each genotype?

c) What will be the genotype frequencies of DD, Dd, and dd in the adults that develop from these seeds and survive to reproduce? How many adults will there be with each genotype?

d) Over a long period of time, what do you expect to happen to the D and d alleles in this population? Why?

BIOL 2081C Lecture Notes - Lecture 32: Zygosity, Allele Frequency, Genotype Frequency

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