gen-define-the-hardy-weinberg-principle-and-give-one-short-worke-d0d7

Define the Hardy-Weinberg principle and give one short worked example.

# Hardy-Weinberg Principle The Hardy-Weinberg principle states that **allele and genotype frequencies in a population remain constant from generation to generation** in the absence of evolutionary influences. ## Key conditions required: - No mutations - Random mating - No gene flow (migration) - Infinite population size (no genetic drift) - No natural selection ## The equations: - **Allele frequencies:** p + q = 1 - **Genotype frequencies:** p² + 2pq + q² = 1 Where: - p = frequency of dominant allele - q = frequency of recessive allele - p² = frequency of homozygous dominant genotype - 2pq = frequency of heterozygous genotype - q² = frequency of homozygous recessive genotype ## Worked Example **Problem:** In a population of 100 cats, 84 have black fur (dominant) and 16 have white fur (recessive). What are the allele frequencies? **Solution:** 1. Frequency of recessive genotype (white cats): q² = 16/100 = 0.16 2. Frequency of recessive allele: q = √0.16 = **0.4** 3. Frequency of dominant allele: p = 1 - 0.4 = **0.6** 4. Expected heterozygotes: 2pq = 2(0.6)(0.4) = **0.48** (48 cats) 5. Expected homozygous dominant: p² = (0.6)² = **0.36** (36 cats)