Biology 1201A Lecture Notes - Lecture 1: Allele Frequency, Genotype Frequency, Null Hypothesis

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orchidshark702

18 Dec 2017

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Population genetics formalizing and applying the hardy-weinberg equilibrium. Frequency of any allele (recessive, dominant, codominant etc. ) are roughly constant if no outside forces are influencing allele frequencies. Recessive alleles aren"t always in low frequency. Allele frequencies can be used to predict genotype frequencies, assuming no outside forces. Predicts genotype frequencies in a population based on allele frequencies when: No selection individuals are not varying in reproduction and survival success. Individuals are mating randomly not paying attention to phenotypes when mating. No sampling (genetic) drift i. e. population is large. No gene flow no new individuals joining the population and adding new alleles. The hwe is a null hypothesis: predicts what will occur if nothing is going on" no change. We use this null hypothesis to determine when changes occur p and q represent the frequencies of two different alleles. When we calculate p2 we are calculating the frequency of individuals that are homozygous for the p allele.

Related Questions

1 A) Cystic Fibrosis is an autosomal recessive disease, 1 out of every 2500 individuals of Caucasian descent in the US have cystic fibrosis. What frequency of cystic fibrosis carriers would you expect in the Caucasian population of the US under Hardy Weinberg Equilibrium? Show your work. (1 pt)

1 B) You know that penguin tuxedo color is a classic Mendelian single-gene trait, the allele for black and white tux coloring (T) is dominant over gray and white tux coloring (t). In a population of penguins, there are 400 black and white tuxedoed penguins and 200 gray and white tuxedoed penguins.

(i) Which observed genotypic or allelic frequencies can be calculated from this scenario without assuming Hardy Weinberg Equilibrium? (1.5 pt)

(ii) In one to two sentences, explain why differences may arise between observed and expected genotype frequencies. (1 pt)

1 C) You are studying inheritance of external keratin features in a dinosaur. Analysis has found that the presence of feathers is due to codominance between the AS (scales) and AH (horns) alleles. In one generation of a population you find 78 scaled dinosaurs, 76 feathered dinosaurs, and 64 horned dinosaurs.

(i) What are the observed allele frequencies of AS and AH ? Use p for the frequency of AS and q for the frequency of AH . Show your work. (1.5 pt)

(ii) What are the observed genotypic frequencies? Show your work. (1 pt)

(iii) Given the allelic frequencies calculated above, what are the expected number of scaled, feathered, and horned dinosaurs in a population of the same size (218) under Hardy Weinberg Equilibrium? Show your work. (1.5 pt)

(iv) Use a chi-square test to examine whether the gene you are studying is under Hardy Weinberg Equilibrium in this population. Show your work. Do you accept or reject the null hypothesis? (2 pts)

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?

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

Biology 1201A Lecture Notes - Lecture 1: Allele Frequency, Genotype Frequency, Null Hypothesis

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