A-Level Biology - 3.7.2 Populations

What is a population?

a group of organisms of the same species

occupying a particular space at a particular time

that can potentially interbreed.

What is a species?

two organisms belong to the same species if they are able to mate to produce fertile offspring

What is a gene pool?

all the alleles in a population

What is allele frequency?

number of times an allele occurs in a gene pool, compared to the total number of alleles in that pool for the same gene

i.e.

number of specific allele/total number of alleles for that gene

What is the Hardy-Weinberg principle?

a mathematical model which predicts that allele frequencies will not change from generation to generation

(if certain conditions are met)

Under what conditions does the Hardy-Weinberg principle apply?

1) mutation is not occurring

2) natural selection is not occuring

3) population is infinitely large

4) all members of the population breed (no selection)

5) all mating is random

6) all individuals produce the same number of offspring

7) no migration in or out of the population

Give the Hardy-Weinberg equation

p² + 2pq + q² = 1

p is the frequency of one (usually dominant) allele

q is the frequency of the other (usually recessive) allele

What do p², 2pq, and q² represent in the Hardy-Weinberg equation?

p² = frequency of homozygous dominant genotype

2pq = frequency of heterozygous genotype

q² = frequency of homozygous recessive genotype