Final - Population Genetics

Question 1

Population genetics

Answer 1

• the study of the distribution of genes in populations and how the frequencies of genes and genotypes are maintained or changed from generation to generation

Question 2

Population

Answer 2

• local group of organisms belonging to a single species

- composed of interbreeding individuals who share a common gene pool

Question 3

Gene Pool

Answer 3

• the set of genes contained in an entire population

Question 4

Allele frequency

Answer 4

• frequency of an allele in a population, as measured by its percentage of the total number of alleles at a particular gene locus

Question 5

Genotype frequency

Answer 5

• percentage of individuals in a population who are homozygous or heterozygous for an allele at a particular locus

Question 6

Hardy Weinberg Law

Answer 6

• can be used to determine allele and gentotype frequencies in a population.
• states these frequencies remain constant from one generation to the next under 5 conditions

Question 7

5 conditions of Hardy Weinberg Law

Answer 7

1. Large population size
2. Random mating between individuals in the population
3. No mutations in the alleles
4. No migration into or out of the population
5. No natural selection (i.e. all genotypes are equally viable and fertile)

Question 8

Equation for Allele Frequency

Answer 8

p + q = 1

A) (a

Question 9

Equation for genotype frequency

Answer 9

p^2 + 2pq + q^2 = 1

(AA) (Aa) (aa)

Question 10

Equation for Frequency of Allele from genotype Frequency

Answer 10

Freq (allele) = Freq (homozygote) + 1/2 Freq (heterozygote)
B = BB + 1/2 Bb
p = p^2 + 1/2 pq

Question 11

Frequency of phenotype => genotype => allele

Answer 11

p = Sqrt (p^2)

a aa

Question 12

Recessive allele Frequency in males

Answer 12

= phenotype frequency, since males have only 1 X chromosome

Question 13

Applications of Population genetics

Answer 13

1. Use in genetic Counseling
2. To plan genetic screening programs
3. In molecular diagnostics testing

Question 14

Consanguineous Mating

Answer 14

• interbreeding

- 2 individuals who share a common ancestor preceeding 2 or 3 generations

Question 15

Assortive Mating

Answer 15

• based on factors like race, ethnic groups, culture differences, religious beliefs, intelligence, language

Question 16

Inbred

Answer 16

• children from the result of consanguineous mating

Question 17

Founder effect

Answer 17

• occurs when a population is formed by a small group of individual
• alleles carried by these “founder” are established in the new population
• ex: discovery of new island

Question 18

Population bottleneck

Answer 18

• change in gene frequency that occurs when a population is suddenly reduced in size and then expands again
• ex: natural disaster = volcano

Question 19

Genetic drift

Answer 19

• random changes in allele frequencies from generation to generation in small population
• caused by founder effect and population bottleneck

Question 20

Fitness

Answer 20

• a measure of the relative survival and reproductive success of a specific individual or genotype

Question 21

Race

Answer 21

• a subdivision of species that has come to differ in the frequencies of alleles it possesses

Question 22

Factors leading to Change in Gene Frequencies

Answer 22

1. Small population size
   - subject to genetic drift
   - race
2. Non- random mating
   - assortive mating
   - consanguineous mating
3. Natural Selection
   - fitness
4. Mutation
5. Migration - rapid introduction of new alleles

Question 23

Heritability

Answer 23

• the degree to which a trait is inherited
• expressed as the proportion of variability caused by genetic differences
• ranges from H = 0 - 1.0

Question 24

H = 1.0

Answer 24

• genetic differences = 100% of variation

- Environmental factors = contribute to 0%

Question 25

H = 0

Answer 25

- Environmental factors = 100% of the variation | - genetic differences = contribute to 0%

Question 26

Genetic variance

Answer 26

- phenotypic variability in a population due to differences in genotypes

Question 27

Environmental variance

Answer 27

- phenotypic variability in a population due to differences in environmental factors

Question 28

How monozygotic twins are used to determine heritability

Answer 28

Monozygotic= genetically identical = 100% Dizygotic = share 50% of their genes - if environmental factors play more of a role, the concordance value will be less than 100% in monozygotic twins and lower than 50% in dizygotic twins

Question 29

Mutation and Polymorphism

Answer 29

- mutation rate = 1 mutation per 100,000 - 1 million copies of a gene - 1 in 10 people is likely to have received a new mutation - mutations established in > 1% of the population are known as polymorphisms

Question 30

Multifactorial Traits

Answer 30

- traits that result from genetic variance (2 or more genes) and environmental variance (1 or more factors) - exhibit continuous variation, in varying degrees along a continuum - ex: height, weight, skin color, intelligence, diabetes mellitus, manic depression