Species: a group of similar organisms that can reproduce to give fertile offspring
Population: A group of organisms of the same species living in a particular area at a particular time
Gene Pool: Complete range of alleles present in a population
Allele Frequency: The frequency of an allele in a population (given as a %)
Hardy-Weinberg Principle
- Used to predict the frequencies of alleles/genotype/phenotype within a population
- It can also be test whether or not the Hardy-Weinberg
principles applies to a particular allele in a particular population
- E.g. if frequencies do change between generations in a large population then there’s an influence of some kind
- The principle will work providing:
- Large Population size
- No immigration/Emigration
- No natural selection
- Random mating (so all possible genotypes can bread with all others)
Allele Frequency
p + q = 1
p = Frequency of one allele (usually dominant)
q = frequency of one different allele (usually recessive)
- the frequencies of both p and q must equal to 1 (100%)
Genotype Frequency
p2 + 2pq + q2 = 1
p2 Frequency of homozygous dominant genotype
2pq = Frequency of heterozygous genotype
q2 = Frequency of homozygous recessive genotype
- Total frequency of all genotypes within a population = 1 (100%)
- Phenotype can also be determine providing that the relation between phenotype and genotype is known
- Principle can also be used if two alleles are
codominant or if whether the allele is recessive and which is dominant is
unknown
- By making p represent one allele and q represent the other