BLG 144 Study Guide - Final Guide: Allele Frequency, Population Genetics, Heredity

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silverlocust396

3 Dec 2018

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Population genetics: study of the frequency, distribution and inheritance of alleles in a population. Alleles: pairs of genes located at a particular spot on matched chromosome. Gene: an ordered sequence of nucleotides along a segment on the dna that codes for protein. Gene pool: sum of all genes in a population. Phenotype: description of one of your physical traits or characteristics. Genotype: the expression or genetic makeup of the phenotype. Each gene has 2 alleles that make up an individual"s genotype. Allele frequency: the proportion of alleles in a population: measured using the hardy-weinberg principle and equation. Because there are 2 alleles the frequency of p+q always add up to 1 (100%: p + q = 1, p= dominant allele, q= recessive allele. Hardy-weinberg equation is a mathematical expression used when evolution doesn"t occur (no change in allele frequencies: p^2 + 2pq + q^2 = 1.

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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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15. Population genetics provides answers for all of thefollowing questions except:

a. What is the frequency ofgenetic disease in a population?

b. What fraction of thephenotypic variation in a trait is the result of geneticvariation?

c. What alleles are most likelyto mutate?

d. Given certain quantifiablevariables, how long is a disease likely to persist?

e. How rapidly can a disease gaina foothold in a population?

16. Which of the following is not one of the assumptions of theHardy-Weinberg law?

a. The population is verylarge.

b. There is non-random matingwithin the population.

c. Mutations in the alleles donot occur.

d. No migration occurs into orout of the population.

e. The ability of all genotypesfor survival and reproduction is the same.

17. The heterozygote genotype frequency term for a gene with twoalternate alleles A (frequency p) and a (frequency q) in theHardy-Weinberg equation is:

a.p² b.q² c.2pq d.(p+q)² e. p+q

18. In humans, brachydactyly is a dominant condition. Sixthousand four hundred people in a population of 10,000 show thedisease (1,600 are BB, 4,800 are Bb) and 3,600 are normalphenotypes (bb). The frequency of the b allele is:

a.0.6 b.0.8 c.0.36 d..48 e. 0.16

19. Fitness is described as:

a. an individualâs ability tosurvive to adulthood

b. an individualâs ability toreproduce

c. an individualâs ability toadapt to change

d. all of the above are true

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Q1. Which of the following statements is true about the disease Kuru?
Kuru is caused by a virus, which is contracted by eating human brain material.
Kuru is caused by a prion (PrP), which is contracted by eating human brain material.
Kuru is caused by a recessive allele for PrP; if a person has two copies, he or she will develop Kuru.
Kuru is caused by a dominant allele for PrP; if a person has two copies, he or she will develop Kuru.
Kuru is caused by having one copy of the dominant allele and one copy of the recessive allele for PrP.

Q2. True or false: One can calculate the frequency of alleles in a population if the genotypes of the members of the population are known.

True False

Q3. The Hardy-Weinberg equation is p2 + 2pq + q2. In this equation, q2 stands for the frequency of ____________ in a population.

The recessive allele O

ne of the homozygous genotypes

The dominant allele

Heterozygous genotype

Q4. Which of the following descriptions best fits the relationship between the terms gene, allele, locus, and chromosome?

Alleles are different forms of a gene, which can be found at a locus on a chromosome.

Genes are made up of chromosomes, which can be found at a locus on an allele.

Chromosomes are different forms of a gene, which can be found at an allele on a locus.

A locus is made up of alleles, which can be found at a gene on a chromosome.

Q5. 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.

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BLG 144 Study Guide - Final Guide: Allele Frequency, Population Genetics, Heredity

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