Estimating Risk of Inherited Genetic Disease Flashcards
Define fitness.
Relative ability of organisms to survive and pass on genes.
How do neutral alleles affect fitness?
Not at all in most cases
How do deleterious alleles affect fitness?
Sometimes decrease
How do advantageous alleles affect fitness?
Rarely increase
What affects the health of the population?
The frequency of alleles in the whole population.
What is a genotype?
A gene with two alleles.
What are the 3 genotypes?
AA
Aa
aa
Frequency of A (p) + Frequency of a (q) =
1.0
What is the ratio in terms of p and q for a punnet square of genotypes Aa and Aa?
p2 : 2pq : q2
What is the constant relative frequency?
p:q
Do dominant conditions become more common at the expense of recessive ones?
No
What are the 2 conditions of HWE?
Allele frequencies remain constant generation to generation.
Relative proportion of genotype frequencies remain constant generation to generation.
What will the allele frequency be no matter what in HWE?
1
Should mutation be ignored for an ideal population?
Yes
Should migration occur for an ideal population?
No
Should mating be random in an ideal population?
Yes
Should there be no selective pressure in an ideal population?
Yes
Should the population size be small in an ideal population?
No
Should allele frequencies by different in the sexes in an ideal population?
No
What happens to alleles as a result of migration or intermarriage?
Introduction of new alleles which leads to hybrid population.
What leads to an increase in mutant alleles?
Non-random mating
What is assortative mating?
Choosing of partners due to shared characteristics.
What is consanguinity?
Marriage between close blood relatives.
What is natural selection?
Gradual process by which biological traits become either more or less common in a population.
Negative selection:
______ reproductive fitness.
______ the prevalence of traits.
Leads to gradual ______ of mutant allele.
Reduces
Decreases
Reduction
Positive selection:
______ reproductive fitness.
______ the prevalence of adaptive traits.
Heterozygote ______.
Increases
Increases
Advantage
What size of populations can exhibit genetic drift and founder effect?
Small
Define genetic drift.
Random increases of one allele transmitted to high proportion of offspring by chance.
Define founder effect.
Reduction in genetic variation when small subset of population establishes a new colony.
What is polydactyly?
Extra fingers/toes
What are the two applications of HWE?
Useful for calculating risk in genetic
Useful for planning population based carrier screening programmes
