The Hardy-Weinberg Principle (19.1)

Population

Any group of individuals of the same species living in the same geographical area at the same time

Genes

The basic unit of heredity

a specific sequence of DNA that encodes a protein, tRNA, rRNA molecule, or regulates the transcription of such a sequence

Governs the expression of a particular trait and can be passed to an offspring

Allele

different form of the same gene occurring on homologous chromosomes

Gene Pool

total of all the alleles for all the genes of all the individuals in a population

Genotype Frequency

proportion of members of a population with a particular genotype

usually expressed as a decimal

Phenotype Frequency

proportion of members of a population with a particular phenotype

usually expressed as a decimal

Allele Frequency

rate of occurrence of a particular allele in a population, with respect to a particular gene
usually expressed as a decimal

Hardy-Weinberg Principle

principle that states that allele and genotype frequencies remain constant from one generation to the next, as long as five conditions are met: (1) the population is large enough that chance events will not alter allele frequencies, (2) mates are chosen on a random basis, (3) there are no net mutations, (4) there is no migration, and (5) there is no natural selection against any of the phenotypes

Hardy-Weinberg Equation

mathematical descriptionof the Hardy-Weinberg principle

used to predict allele and genotype frequencies in a population

usually stated: if the frequency of allele A is p and the
frequency of allele a is q, then the genotype
frequencies after one generation of random mating
will always be p 2 + 2pq + q2 = 1.00

Genetic Equilibrium

condition of a gene pool in whichallele frequencies remain constant over time

a population at genetic equilibrium is not changing or evolving

Microevolution

gradual change in allele frequencies in a population over time