# What do the values in the Hardy-Weinberg equation, p2 + 2pq + q2 = 1, represent?  How can this equation be used to measure how dominant or recessive alleles change in a population from generation...

What do the values in the Hardy-Weinberg equation, p2 + 2pq + q2 = 1, represent?  How can this equation be used to measure how dominant or recessive alleles change in a population from generation to generation?

sciencesolve | Teacher | (Level 3) Educator Emeritus

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You need to know that the term `p^2` , in Hardy-Weinberg equation, represents the frequency of genotype AA, where A represents the dominant allele of a certain trait.

The term `q^2` represents the frequency of genotype aa, where a represents recessive allele of a certain trait.

The term 2pq represents the frequency of genotype Aa.

The Hardy-Weinberg equation allows to notice if the evolution in a population occurs by checking the frequencies of genotypes AA, Aa and aa.

Hence, considering the frequency of dominant alleles p = 0.75 and the frequency of recessive alleles q = 0.25, you may evaluate the frequency of individuals that are heterozygous, using Hardy-Weinberg equation, such that:

`2pq = 2*0.75*0.25 = 0.375`

Hence, evaluating the percentage of heterozygous individuals in a population yields that 37.5% individuals that are heterozygous.

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