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Flashcards in Population Genetics Deck (23)
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1
Q

What is population genetics?

A

The study of the distribution of genetic variation in a population.

2
Q

gene pool

A

collection of all the alleles at a particular locus in a population

3
Q

Key assumptions for Hardy-Weinburg equilibrium

A
  1. No new mutations
  2. No evolutionary selection
  3. No migration
  4. Infinitely large population
  5. Matings are random
4
Q

How to calculate the carrier frequency

A

Calculate 2pq

5
Q

Problems with random mating

A
  1. Stratification
  2. Assortative mating
  3. Consanguinity
6
Q

Maple Syrup Urine Disease

A
  • consanguinity
  • caused by founder effect: original founder carried allele
  • genetic isolates
7
Q

What is evolution?

A

The process whereby the fittest alleles are selected

8
Q

Fitness (f)

A

A measure of the number of offspring of affected persons who survive to reproductive age

9
Q

f=0

A
  • causes death

- no fitness

10
Q

f between 0 and 1

A

-deleterious

11
Q

f=1

A

just as likely to be represented in next generation as wild type allele

12
Q

Coefficient of selection

A
  • the proportion of mutant alleles that are not passed on and are lost because of selection
  • s = 1 - f
13
Q

If s = 1, it means….

A

it is a genetic lethal

14
Q

Why is selection on autosomal recessive disorders slow/ineffective?

A
  • Most individuals with recessive allele are heterozygous
  • Heterozygotes have the same phenotype (and fitness) as homozygous dominant individuals
  • Selection can only act on expressed traits.
15
Q

Why does selection on autosomal dominant disorders happen much more quickly?

A
  • Exposed to selection
  • Heterozygotes have the same phenotype as homozygous dominant individuals, so they will also be selected against
  • If zero fitness, new cases have to come from de novo mutation
16
Q

Genetic drift

A

changes to allele frequencies due to random chance/sampling error

17
Q

Population bottlenecks

A

Occur when many member of a group die, and few remain to re-start the population

18
Q

Fixed allele

A

the only allele for a single gene in the population

19
Q

Lost allele

A

No longer found in the population

20
Q

Loss of heterozygosity

A

As we get drift towards loss/fixation, heterozygote frequency decreases

21
Q

Does heterozygosity increase or decrease with every generation with a fixed population?

A

decrease

22
Q

Characteristics of an ideal population

A
  1. males = females
  2. All animals can reproduce
  3. All animals equally likely to produce offspring
  4. Mating is random
  5. Population size is constant
  6. No migration/mutation/selection
23
Q

Effective population size equation

A

Ne = 4(Nm)(Nf)/(Nm + Nf)