1. The Hardy Weinberg Principle Flashcards
Define species
Group of similar organism that can reproduce to give fertile offspring
Define population
Group of organisms of the same species living in w particular area at a partcijylst time - potential that they can interbreed
Define gene pool
Complete range of alleles present in population
How often allele occurs in population is called allele frequency - %%% of total population
What is the hard Weinberg principle
It Predicts the frequencies of alleles/ genotypes / phenotypes in a population won’t change from one generation to the next.
This prediction is only true under certain circumstances
•large pop no immigration/ emigration/ mutations / natural selection
•needs to be random mating
What happens if frequencies do change between generations in large population
There’s been an influence of some kind
Allele frequency equation
p + q = 1
p = the frequency of one allele - usually dominant
q = frequency of other allele - usually recessive
The total frequency of all possible alleles for a characteristic in a certain population is 1.0 - 100% so recessive and dominant allele must add up to 1
If allele frequencies add up to more than 1 then they’re not the allies for same gene
If add up to less than 1 there’s more than 2 alleles for that gene
Genotype frequency equation
p2 + 2pq + q2 = 1
Total frequency of all possible genotypes for one character in certain population is 1.0
3 genotypes : homozygous recessive/ homozygous dominant and heterozygous = all add up to 1
What does the genotype frequency equation mean ?
p2 = frequency of homozygous dominant
2pq = frequency of heterozygous
q2 = frequency of homozygous
What can the genotype frequencies then be used to work out ?
Phenotype.
Eg genotype of plant Rr where R codes for red flower which is dominant over r - the phenotype would be red flowers
