Cells 21

What is a population?

A localized group of individuals of the same species.

What is a gene pool?

The total collection of genes and alleles in a population.

What is the Hardy-Weinberg equation for allele frequencies?

p + q = 1.

What is the Hardy-Weinberg equation for genotype frequencies?

p² + 2pq + q² = 1.

What does p represent in Hardy-Weinberg?

The frequency of the dominant allele.

What does q represent in Hardy-Weinberg?

The frequency of the recessive allele.

What does p² represent?

Homozygous dominant genotype frequency.

What does 2pq represent?

Heterozygous (carrier) genotype frequency.

What does q² represent?

Homozygous recessive genotype frequency.

For an autosomal recessive disease, which Hardy-Weinberg term equals the disease frequency?

q².

How do you calculate carrier frequency for an autosomal recessive disease?

2pq.

For an X-linked recessive disease, what proportion of males are affected?

q.

For an X-linked recessive disease, what proportion of females are affected?

q².

What is genetic drift?

Random changes in allele frequencies due to chance.

In which populations is genetic drift strongest?

Small populations.

What is the bottleneck effect?

A drastic reduction in population size causing loss of genetic diversity.

What is the founder effect?

A small group starts a new population with reduced genetic variation.

What type of selection favors the average phenotype and reduces variation?

Stabilizing selection.

What are the three major types of natural selection?

Stabilizing, directional, and disruptive selection.