Population genetics Flashcards
Define polymorphism
When there are variants of an allele that occur in greater than 1% of a population
What is the allele that determines immune response?
HLA
What is an example of non-polymorphic genes? Why are these not polymorphic?
Histones
Because a mutation would have a very deleterious effect on the organism
What are the four assumptions made for the hardy-Weinberg model to hold true?
Large population size
Equal fitness of offspring
Random mating
No influx of new alleles by migration/mutation
What are the four factors that run counter to the four assumptions made by the Hardy-Weinberg model?
Genetic drift
Selection
Random mating
population bottlenecks and founder effects
What is genetic drift?
Normal statistical variations that can occur in small populations
What is selection?
When not all alleles bestow equal fitness to the organism
What is assortive mating?
Selection of sex partners based on similar traits (counter to the random mating)
What is the effect of assortiv mating?
An increase in the number of homozygous individuals, not the allele frequency
What are population bottlenecks and the founder effect?
Population bottle neck is when there is a significant loss of genetic variation due to the death of a large percent of the population.
Similarly, founder effect is when there is a common ancestor(s) of a population
What is linkage disequilibrium?
It describes the dissimilar percentage of alleles present is a population, after two alleles in very close proximity undergo recombination.
What is the disease common among the amish of pennsylvania? What principle of of population genetics does this demonstrate?
Ellis van Crevald syndrome (a type of skeletal dysplasia).
Caused by the founder effect
What is the disease that is common among Ashkenazi Jews?
tay-sachs disease
What is the disease that is common amongst french canadians?
Tyrosinemia
What is the reason for the prevalence of cystic fibrosis in Europeans?
CFTR transporter is less susceptible to typhoid fever.
