1. The Hardy Weinberg Principle Flashcards Preview

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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 ?


Eg genotype of plant Rr where R codes for red flower which is dominant over r - the phenotype would be red flowers