BISC 202 Lecture Notes - Lecture 30: Sickle-Cell Disease, Genetic Drift, Silent Mutation

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burgundycoyote951

13 Dec 2016

School

Simon Fraser University

Department

Biological Sciences

Course

BISC 202

Professor

Michael Hart

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Document Summary

Bisc202 lecture 30: population genetics and the hardy weinberg equilibrium (ii) One generation later, the population will be the expected population numbers (calculated from the allele frequencies) If all assumptions of hwe are met, only 1 generation is required to display the genotypic frequencies/#s and this hwe will be maintained. (cid:882). (cid:888)(cid:885)(cid:884) + (cid:4666)(cid:882). (cid:887) (cid:882). (cid:884)(cid:885)(cid:890)(cid:4667) = (cid:882). (cid:889)(cid:887)(cid:883) When given frequencies, can just add the homozygote frequency to half of the heterozygote frequency to find the allele frequency. All frequencies must add up to 1. Can"t use hwe formula (square rooting frequencies then using 2pq) because the population is not at hwe (unless it is known from question or x2 test) What are the allele frequencies? (p and q) Consider a1, a2, a3 with the following allele frequencies respectively: P = 0. 5, q = 0. 3, r = 0. 2. For a population at hwe, assume that you are randomly drawing 2 alleles from the gene pool.

Related Questions

Q5. A sunflower population in Hardy-Weinberg equilibrium has the following allele frequencies for petal color: 0.75 dominant, 0.25 recessive. If the assumptions of Hardy-Weinberg equilibrium continue to hold, then after 200 generations:

The allele frequencies will be: 0.75 dominant and 0.25 recessive.

The allele frequencies will be: 0.50 dominant and 0.50 recessive.

The allele frequencies will be: 1.0 dominant and 0 recessive. T

here is no way to predict allele frequencies, given the information provided.

Q6. Mead and his colleagues proposed a hypothesis for the apparent heterozygote advantage for the PrP locus. What did they suggest as the basis for the high presence of both alleles?

History of cannibalism.

Protection from malaria.

Protection against plague.

They did not propose a heterozygotic advantage for the PrP locus.

Q7. A frog population has two alleles for skin color at the following relative frequencies: Allele SC1= 0.8, Allele SC2 = 0.2. Allele SC2 is:

Dominant

Recessive

Co-dominant

Impossible to determine dominance from the information given.

Q8. A bird population has two alleles for feather color at the following relative frequencies: Allele FC1 = 0.5, Allele FC2 = 0.5. Allele FC1 is:

Dominant

Recessive

Co-dominant

Impossible to determine dominance from the information given.

Q9. Use the following information for both questions 9 and 10: You encounter a few populations of millipedes with variation in skin color. Genotype can be inferred from coloration: CC millipedes are black, Cc millipedes are brown, and cc millipedes are yellow. [You can launch a calculator byclicking here.] If one millipede population has 60 black individuals, 20 brown individuals, and 20 yellow individuals, what is the relative frequency of allele C in that population?

0.5

0.6

0.7

0.8

Impossible to calculate from the information given.

Q10. If another millipede population's allele frequencies are 0.5 for C and 0.5 for c, what is the expected frequency of the cc genotype in the population, if the population is in Hardy-Weinberg equilibrium?

0.125

0.25

0.5

1.0

Impossible to calculate from the information given.

viridianlocust882

Hardy and Weinberg (one a genetics expert and the other a mathematician) independently demonstrated that the alleles within populations may be stable under certain conditions. If the allele frequency is variable, they will change, and evolution is possible. If the allele frequencies are stable, will evolution be possible? THINK about this... by definition, evolution will NOT occur when the allele frequencies are stable.

1) What are the assumptions for STABLE allele frequencies for a population from one generation to the next?

2) Next, what occurs if any of these assumptions do not hold true (another words...the assumption do NOT apply)?

3) From the list of assumptions, select one (only ONE) and describe how it may/may not apply to a ânatural populationâ (this where things get very cool...)

purpleduck821

The Hardy-Weinberg equation provides a way to predict genotype frequency based on allele frequency. In the case of mammals, males are hemizygous for X-linked genes, whereas females have two copies. Among males, the frequency of any X-linked trait equals the frequency of males with the trait. For example, if an allele frequency for an X-linked disease-causing allele was 5%, then 5% of all males would be affected with the disorder. Female genotype frequencies are computed using the Hardy-Weinberg equation.

Consider the human X-linked trait known as hemophilia A. In human populations, the allele frequency of the hemophilia A allele is approximately 1 in 10,000, or 0.0001. The other allele for this gene is the normal allele. Males can be affected or unaffected, whereas females can be affected, unaffected carriers, or unaffected noncarriers.

A. What are the allele frequencies for the mutant and normal allele in the human population?
B. Among males, what is the frequency of affected individuals?
C. Among females, what is the frequency of affected individuals and heterozygous carriers?

scarletcrocodile235

BISC 202 Lecture Notes - Lecture 30: Sickle-Cell Disease, Genetic Drift, Silent Mutation

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