7B - The Hardy-Weinberg principle Flashcards
What do members of a population share?
A gene pool.
What is a species?
A group of similar organisms that can reproduce to give fertile offspring.
What is a population?
A group of organisms of the same species living in a particular area at a particular time - so they have the potential to interbreed.
What does a population have the potential to do?
Interbreed
How many populations of a species are there?
Species can exist as one or more populations.
What is the gene pool?
The complete range of alleles present in a population.
What is allelic frequency?
How often an allele occurs in a population.
What is allelic frequency often given as?
A percentage of the total population (e.g. 35%) or a number (e.g. 0.35).
What does the Hardy-Weinberg Principle predict?
That allele frequencies won’t change from one generation to the next.
What is the Hardy-Weinberg principle?
A mathematical model that predicts that the frequencies of alleles in a population won’t change from one generation to the next.
When is the Hardy-Weinberg principle correct? Under what conditions?
Has to be a large population where there is no immigration, emigration, mutations or natural selection. There also needs to be random mating - all possible genotypes can breed with all others.
What is random mating?
Where all possible genotypes can breed with all others.
What can the Hardy-Weinberg equations be used to calculate?
The frequency of particular alleles, genotypes and phenotypes within populations.
What can the Hardy-Weinberg equations be used to test?
Whether or not the Hardy-Weinberg principle applies to particular alleles in particular populations, i.e. to test whether selection or any other factors are influencing allele frequencies.
If frequencies do change between generations in a large population then there is an influence of some kind.
When is there an influence of some kind?
If frequencies do change between generations in a large population.
What are the Hardy-Weinberg equations?
p + q = 1
p2 + 2pq + q2 = 1
What do the p and q mean in the Hardy-Weinberg equations?
p = the frequency of one allele, usually the dominant one.
q = the frequency of the other allele, usually the recessive one.
What do the p2, 2pq and q2 mean in the Hardy-Weinberg equations?
p2 = the frequency of the homozygous dominant genotype.
2pq = the frequency of the heterozygous genotype.
q2 = the frequency of the homozygous recessive genotype.
What can genotype frequencies be used to work out?
Phenotype frequencies.
What can you work phenotype frequencies out from?
Genotype frequencies.
