Population Genetics

Question 1

4 ideal characteristics for a population?

Answer 1

large pop size
equal fitness of offspring
random mating
no influx of new alleles by migration or mutation

Question 2

There are no ideal populations so what 4 things explain what actually happens in them?

Answer 2

Genetic Drift (small pop)
Selection (fitness is unequal)
Assortative Mating (mating is nonrandom)
Population bottlenecks/founder effect

Question 3

What 3 things will affect allele frequency over time?

Answer 3

genetic drift, selection and population bottlenecks

Question 4

Describe the concept of genetic drift.

Answer 4

can lead to the disappearance or multiplication of rare alleles in a small population

Question 5

Describe the concept of selection.

Answer 5

individual homozygotes for a mutant allege can be eliminated from a population; however, at some point new mutations make up for this.

Question 6

Salmonella typhimurium displays what concept in terms of population genetics.

Answer 6

positive selection.

Question 7

What are 4 other disease also display positive selection for heterozygotes?

Answer 7

CFTR, Sickle Cell, B-thalassemia, Hemochromatosis

Question 8

Describe the concept of assortative mating.

Answer 8

Select a mate based on specific genetic trait; causes a disturbance in equilibrium (however, no alleles are lost).

Question 9

Consanguineous matings do NOT change the allele frequencies in the gene pool. However, they do change something. What is this?

Answer 9

increase in homo freq beyond the expected level

Question 10

COnsanguineous matings increase the risk for genetic diseases at what %?

Answer 10

5% (2% is normal population)

Question 11

Describe the concept of population bottlenecks.

Answer 11

if large part of population is wiped out, only a small found population is there to recover. THis leads to amplification of rare alleles.

if a new territory is populated by a small founder pop, this also leads to amp.

A rare polymorphism in a member of the founding group will later be found in a large proportion of the population derived from the founder

Question 12

What is Ellis Van Creveid syndrome?

Answer 12

rare genetic disease related to the concept of founder effect.

due to a recessive mutation in teh EVC gene

Question 13

In what type of study are millions of SNPs analyzed to compare the prevalence of SNPS in patients their patients to controls?

Answer 13

genome wide association studies

Question 14

What is the key to having a successful association study with a high degree of disequilibrium?

Answer 14

young, genetically isolated populations

Question 15

What must one assume about small populations for linkage disequilibrium research to succeed? (2 things)

Answer 15

1. few genes contribute to the disease

2. genetic factors are the same for all patients

Question 16

What is the one downside to working with small populations?

Answer 16

less statistical power in the data