7.2 Population Genetics

What is meant by population

A group of organisms belonging to the same species found in the same area at the same time

what is meant when we refer to allele frequencies and a gene pool

how often an allele of a gene occurs in a population this is often represented as a proportion e.g 50%

why some genotypes cannot be determined by looking at phenotypes

some alleles are recessive, an individual with a heterozygous genotype will display the dominant trait in their phenotype

to identify such genotypes cross with homozygous recessive, offspring with recessive traits identifies the other parent as heterozygous

what does the hardy Weinberg principle predict

looks at the allele frequency within populations

predicts that the frequency of the alleles of one gene in particular population will stay the same from generation to generation

what are the conditions required for the hardy Weinberg principle to be valid

The population is large(in small populations chance events can cause large changes in allele frequency)

no immigration or emigration(causes new alleles to enter or existing alleles to leave)

there is no random mating between the individuals in the population(ensures each allele has the same chance of being passed onto the next generation)

there is no gene mutation(cause same alleles to a different allele on the same gene)

all genotypes have the same reproductive success

mathematical equations used to express allele and genotype frequencies

p²+2pq+q²=1

p + q= 1

p=frequency of dominant allele

q=frequency of recessive allele

p²=frequency of homo dominant

q²=frequency of homo recessive

2pq=frequency of hetero