Lectures 8 and 9: Population Genetics

Question 1

What is a population?

Answer 1

A group of interbreeding individuals f the same species that inhabit the same space and time

Question 2

What is a gene pool?

Answer 2

All of the alleles present and carried by the population

Question 3

What is population genetics?

Answer 3

Changes in the frequency of the alleles in a gene pool over time

Question 4

Selection can occur when ___________________________________________.

Answer 4

one genotype is more “fit” than another

Question 5

What is a heterozygote advantage?

Answer 5

An individual heterozygous at a particular locus exhibits greater biological fitness

Question 6

What is the Founder Effect?

Answer 6

Disproportionate effect on gene frequencies that can

occur when a new population is founded by a small group of individuals from a larger population

Question 7

With respect to medical genetics, what is a founder?

Answer 7

Used to describe the first person in a community who displays the symptoms of a particular genetic disorder

Question 8

What is Genetic Drift?

Answer 8

Random chance fluctuation in the frequency of a gene in the absence of selection. Allele frequency can increase to fixation (100%) or can be lost from the gene pool by random chance.

Question 9

Random Genetic Drift generally occurs in ________________.

Answer 9

Small Populations

Question 10

What is the effective population size (Ne)?

Answer 10

The proportion of the population that is capable of reproduction, on average 1/3 of population

Question 11

What is Endogamy?

Answer 11

A preference for individuals to marry within their

own specific community

Question 12

What is Consanguinuity?

Answer 12

Marriage between close biological relatives

Question 13

What is Phenotypic Frequency?

Answer 13

The proportion of individuals within a population that are of a particular phenotype

Question 14

What is Genotypic Frequency?

Answer 14

The proportion of individuals within a population that are of a particular genotype

Question 15

What is Allelic Frequency?

Answer 15

The proportion of all copies of a gene in a population that are of a particular allele type

Question 16

The frequency of the dominant allele is denoted __ and the formula for calculating it is ____________.

Answer 16

p

p = F(AA) + 1/2F(Aa)

Question 17

The frequency of the recessive allele is denoted __ and the formula for calculating it is ____________.

Answer 17

q

q = F(aa) + 1/2F(Aa)

Question 18

What is the Hardy-Weinberg Equation?

Answer 18

q^2 + 2pq + p^2 = 1 OR (p + q)^2 = 1

Question 19

What are the assumptions of the Hardy-Weinberg Equation?

Answer 19

• Mating is random
• Allelic frequencies are the same in males and females
• All genotypes have equivalent viability and fertility
• Mutation does not occur
• Migration into the population is absent
• Population is large so that allelic variations do not occur by chance

Question 20

What causes a deviation from the Hardy-Weinberg equilibrium?

Answer 20

• Non-random mating (e.g. inbreeding)
• Gene flow (e.g. migration)
• Genetic drift
• Mutation
• Natural Selection
• Genotyping errors