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18 Cards in this Set
- Front
- Back
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Define: the equation which permits a calculation of the relative frequencies of alleles within an idealized population.
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Hardy-Weinberg Equilibrium
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What is the hardy-weinberg equation?
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p^2 + 2pq + q^2
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List the five assumptions of Hardy Weinberg
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Large population size
Nonrandom mating No selection No migration No mutation |
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What is Hardy-Weinberg equilibriuM?
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A population whose genotype frequencies follow the Hardy-Weinberg relationship (via the equation equaling 1) and are stable in succeeding generations.
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What are some factors which affect the assumption of a large population for HW?
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Genetic drift
Founder effect - Both result in an otherwise rare allele becoming more prevalent. |
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What are two factors which can affect the HW assumption of Nonrandom mating.
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People making selections
Consanguinity |
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What is one factor affecting the HW assumption of selection?
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biological fitness (defined as reproductive fitness)
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Give an example of a balanced polymorphism.
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Sickle cell anemia
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Define: When a genetic variant is maintained at a relatively high frequency in a population due to selections against both homozygotes, with the heterozygotes being the most fit.
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Balanced polymorphism
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Give two examples of balanced polymorphic diseases.
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Sickle cell anemia
Cystic fibrosis |
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Define: When two or more alleles maintained in the population at a frequency such that the rarest coult not be maintained bya recurrent mutation alone.
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Polymorphic
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Define: Diseases which result from the interaction of multiple genes are said to be _________.
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Polygenic
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Disease which result from the interaction of genes with the environment are said to be ________.
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Multifactorial
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List two characteristics typical of multifactorial polygenic disease.
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the disease frequency is higher among relatives of affected individuals and is proportional to the degree of relatedness
The proportion of affected relatives is inconsistent wtih autosomal dominant or recessive inheritance (even assuming incomplete penetrance) |
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What does "degree of relationship" mean?
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Firs degree relatives are parents, children or siblings of the affected individual and share half of their genes with that individual.
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How have twin studies emonstrated evidence for the multifactorial nature of some diseases?
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Traits that are entirely genetic should be 100% concordant in monozygotic twins and 50% concordant in dizygotic twins and 25% for a recessive trait. Traits that are entirely nongenetic should be equally concordant in both MZ and DZ twins.
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What does the term Concordance mean?
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Both members of a twin pair either lacking or having a trait in twins.
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what model proposes that while there is acontinuous distribution of genetic liability this liability must exceed a certain threshold before an abnormal phenotype is seen.
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Threshold model.
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