allele frequency

• • Allele frequency is a measure of how common a specific allele is in a population. Allele frequency can be calculated using the formula: 
• • All allele frequencies in a population must add up to 1.0. Allele Frequency = Number of copies of a specific allele Total number of alleles in a population
• • Sometimes there are more than 2 alleles for a gene in a population, e.g. ABO blood groups. Therefore, the denominator would be the total number of all the different alleles. It’s possible to calculate genotype and phenotype frequencies as well.
• • Scientists measure gene and allele frequencies and use the data to predict how external factors such as selective pressures influence these frequencies.
• • Allele frequency – how often we see each allele (W allele and w allele)
• • Genotype frequency – how often we see each allele combination (WW, Ww and ww)
• • Phenotype frequency – how often we see each phenotype (purple and white colour)