Biology - 7.2 Populations

What is a population?

A group of organisms of the same species in one are a at one time that can interbreed

What is a gene pool?

All the alleles of all the genes in a population at any one time

What is allele frequency?

Proportion of an allele of a gene in a gene pool (decimal or %)

What does the Hardy-Weinberg principle state and what are the conditions under which the principle applies?

• Allele frequencies will not change from generation to generation, given:

  • Population is large

  • No immigration / emigration (to introduce / remove alleles)

  • No mutations (to create new alleles)

  • No selection for / against particular alleles

  • Mating is random

What is the Hardy-Weinberg equation?

p² + 2pq + q² = 1

p = frequency of one (usually dominant) allele of the gene

q = frequency of the other (usually recessive) allel of the gene

p² = frequency of the homozygous (usually recessive) genotype

2pq = frequency of the heterozygous genotype

q² = frequency of the homozygous (usually dominant) genotype