Population genetics

Question 1

Population genetics

Answer 1

take into account the way allele frequency changes over time and genotype frequencies

Question 2

Allele frequency

Answer 2

number of alleles X in a population/number of total alleles in a population

Question 3

Genotype frequency

Answer 3

number of genotype X in a population/ number of total genotypes

Question 4

Hardy- Weinberg equilibrium equation

Answer 4

p2 + 2pq + q2= 1

Question 5

What are the assumptions of the Hardy- Weinberg equilibrium?

Answer 5

1. Big population
2. Random mating
3. Absence of migratory flux
4. Absence of selective pressure on genotypes
5. Absence of new mutations

Question 6

Inbreeding coefficient

Answer 6

F = Σ (0.5^n) (1+Fn)

Question 7

How often does alleles mutate?

Answer 7

u= 10^-5 - 10^-6

Question 8

Equation for the variation of allelic frequency due to spontaneous mutations

Answer 8

(1-u)^t =pt/po

Question 9

Genetic drift

Answer 9

Random change in allele frequency

Question 10

Causes of genetic drift

Answer 10

1. Sampling errors: smaller populations have a larger sampling variance
2. Founder effect
3. Bottleneck effect

Question 11

Founder effect

Answer 11

A population is established from a small number of breeding individuals

Question 12

Bottleneck effect

Answer 12

A population is drastically reduced in size

Question 13

What does it mean that an allele is fixed?

Answer 13

When the allele frequency reaches a value of 0.0 or 1.0 and there is no change in allele frequency unless another allele is reintroduced through mutation/migration

Question 14

Fixation probability

Answer 14

1/2N

Question 15

Elimination probability

Answer 15

1- 1/2N

Question 16

Migration equation

Answer 16

Δpc = m( pD- pR)
Δpc= allelic frequency variation
pD= donor allelic frequency
pR= recipient allelic frequency
m= migration fraction

Question 17

Monodirectional gene flux

Answer 17

one population moves into another

Question 18

Bidirectional gene flux

Answer 18

2 populations migrate to form a new one

Question 19

Factors of natural selection

Answer 19

1. survival and adaptation
2. efficiency of mating
3. fecundity

Question 20

Directional selection

Answer 20

An extreme is favoured

Question 21

Stabilising selection

Answer 21

Intermediates are favoured

Question 22

Disruptive selection

Answer 22

The 2 extremes are favored

Question 23

Fitness

Answer 23

s= 1-w
s: selection coefficient

Question 24

When is the sum of the Hardy-Weinberg equation not equal to 1?

Answer 24

In a changing population because our population is not fit in terms of the selection applied

Question 25

Hardy-Weinberg with fitness

Answer 25

p2WAA/ W + 2pqWAa/W + q2Waa/ W= 1

Question 26

Hardy-Weinberg with fitness frequency of allele A

Answer 26

p2WAA/ W + pqWAa/W = freq A

Question 27

Hardy-Weinberg with fitness frequency of allele a

Answer 27

pqWAa/W + q2Waa/ W= freq a

Question 28

Cases of overdominance

Answer 28

Sickle cell anemia
Phenylketonuria
CF

Question 29

How is phenylketonuria an example of overdominance?

Answer 29

The heterozygous state can protect against the toxic effects of ochratoxin A

Question 30

How is CF an example of overdominance?

Answer 30

Carriers of CF gene may have resistance to bacterial toxin-mediated diarrhoea