What is the equation representing a genotype in the Hardy-Weinberg model?

The equation that represents a genotype in the Hardy-Weinberg model is indeed formulated as p² + 2pq + q² = 1. This equation describes the expected frequencies of genotypes in a population that is in genetic equilibrium, meaning that the population is not experiencing any evolutionary forces such as selection, mutation, migration, or genetic drift.

In this equation, p represents the frequency of the dominant allele, while q represents the frequency of the recessive allele. The term p² corresponds to the frequency of the homozygous dominant genotype (AA), 2pq corresponds to the frequency of the heterozygous genotype (Aa), and q² corresponds to the frequency of the homozygous recessive genotype (aa). When you add these three components together, they equal 1, representing the total genotype frequency in the population.

This fundamental principle allows biologists to predict the genetic structure of a population across generations if the conditions of the Hardy-Weinberg equilibrium are met. Thus, using this equation, one can assess whether the allele frequencies in a population remain constant over time, which is crucial in the fields of population genetics and evolutionary biology.