ABSTRACT
The Hardy-Weinberg Law is a model which predicts the genotype frequencies at a marker locus in generation n + 1, from their frequencies at generation n, provided that no external force is operating that may change the allele frequencies. The model describes a single, independent marker locus with two alternative alleles, A, a. The genotypes at the locus are expressed completely in the phenotypes of the organisms, which can therefore be recognized and counted. When an allele is recessive, genotype counts do not reveal how frequent it is in the population: many of the carriers will be heterozygotes, in which the character is not expressed in the phenotype. Many genetic diseases in humans are due to recessive alleles. The case of complexity in calculating equilibrium frequencies concerns sex-linked genes. In many diploid organisms, males and females differ in one pair of chromosomes, referred to as the x-y system.
