Population Genetics

What are the assumptions of the Hardy-Weinberg Law?

1. population is large 2. matings are random. 3. allele frequencies remain constant over time because there is no appreciable rate of mutation. individuals with all genotypes are equally capable of mating and passing on their genes, that is, there is no selection against any particular genotype. There has been no significant immigration of individuals from a population with allele frequencies very different from the endogenous population.

What factors is population genetics concerned with?

Both genetic factors and environmental factors. These factors determine the frequency and distribution of alleles and genotypes in families and communities.

How many genotypes are possible in males and females for X-linked Recessive conditions?

Males can have 2 genotypes = XY, xY Females can have 3 genotypes = XX, Xx, xx

What is population genetics?

a quantitative study of the distribution of genetic variation in populations and of how the frequencies of genes and genotypes are maintained or changed.

What is the Hardy-Weinberg Law?

allows for the calculation of the frequencies of genotypes in a population if the frequencies of the alleles of an autosomal or X-linked recessive gene are known.

what does hemizygous mean?

carry only one copy of the altered gene. Males are hemizygous with x-linked recessive disorders. the frequency of affected males is the same as the gene frequency for the mutant allele, q, and the frequency of normal males is the frequency of the wild type allele, p.

What is consanguinity and inbreeding? it also messes up hardy-weinberg equilibrium.

consanguintiy brings about an increase in the frequency of the autosomal recessive disease by increasing the frequency with which carriers of an autosomal recessive disorder mate. consanguinity allows very rare disorders to be fairly present. Example. amish.

What is an exception to the constant allele frequencies?

genetic drift. if the population is small, random effects, such as increased fertility or survival of the carriers of a mutation, occuring for reasons unrelated to carrying the mutant allele may cause the allele frequency to change from on generation to the next.

What does p, q and pq represent?

p = dominant gene q = recessive gene pq = heterozygous

What is a factor that disturbs Hardy-Weinberg equilibrium?

population bottleneck. where the population suddenly contracts to a small size and then grows again to a large populatio. gentic drift can result in sudden and dramatic changes in allele frequency that occur independently of selection. Example - Navajo were slauttered. a few survived the genes left contained a recessive disorder called ichthyosis.

what is the founder effect?

similar to genetic drift. occurs when a new colony is started by a few members of the original population. this small population size means that the colony may have: reduced genetic variation from the original population. or a non-random sample of the genes in the original population.

What are the exceptions to the hardy-weinbeger theory: Exceptions to a large population with random mating?

stratification in the population exists and people only breed within a certain group. traditionally populations were divided by race.

What are the exceptions to the hardy-weinbeger theory: Assortative mating?

the choice of a mate because the mate possesses some particular trait. i.e. looks, intellegence. Example - little people