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Hardy- weinberg 23.2. Amy Watkins Andrea Ratti Natalie Saint. Gene pools and allele frequencies. Population A group of individuals of the same species living in the same area and interbreed. Some populations are isolated from each other therefore hardly exchange genetic material.
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Hardy-weinberg23.2 Amy Watkins Andrea Ratti Natalie Saint
Gene pools and allele frequencies • Population • A group of individuals of the same species living in the same area and interbreed. • Some populations are isolated from each other therefore hardly exchange genetic material. • Ex. Animals that live on separated islands or lakes. • However members of a population still breed with each other making them more closely related. • Gene Pool • Characterizing a populations genetic makeup by taking all of the alleles for all loci from all the individuals of a population. • Only one allele for a locus is said to be fixed in gene pool. This makes all of the individuals homozygous for the allele. • Two or more alleles for one locus then the individuals can be homozygous or heterozygous for the allele.
Hardy-weinberg principle • The gene pool of a population that is not evolving. • This principal states that the frequency of alleles and genotypes in a population will remain constant through generations. • Only Mendalian segregation and recombination of alleles influence the population. • Because it is remaining constant it is considered at equilibrium (Hardy-Weinberg equilibrium) • Instead of focusing on one genetic cross the focus is on the combination of alleles for all genetic crosses in a population. • Alleles are selected at random from the whole population, which is based on the fact that mating is random and all male-female mating's are equally possible.
Hardy-weinberg equation • p^2 + 2pq + q^2 = 1 • p = the expected frequency of genotype 1 (homozygous) • pq = the expected frequency of genotype 2 (heterozygous) • q = the expected frequency of genotype 3 (homozygous) • For a locus with two alleles only three genotypes are possible • The sum of the frequencies of the three genotypes must equal one (100%) for any population, regardless if it is in equilibrium.
Conditions for Hardy-Weinberg • 1) No mutations • 2) Random mating • 3) No natural selection • 4) Extremely large population • 5) No gene flow (allele moving in or out)