Flashcards in Estimating risk of inherited genetics Deck (23)
1
Define fitness
means the relative ability of organisms to survive and pass on genes
2
What effects fitness
alleles
3
What do genotype frequencies calculate
How many genotypes in the population
4
How do we calculate genotype frequency
the number of people with that genotype divided by the number of people overall
5
What must an allele frequency always add up to
1
6
What is the genotype frequency equation for
AA : Aa : aa
p2 : 2pq : q2
7
What is the allele frequency of A:a
p:q
8
What do the allele frequency and genotype frequency of the Hardy-Weinberg equilibrium prove to us
Relative frequencies always remain constant therefore dominant alleles don't become more common
9
What is an idea population that will fit withHardy-Weinberg equilibrium
Mutation can be ignored
Migration is negligible (No gene flow)
Mating is random
No selective pressure
Population size is large
Allele frequencies are equal in the sexes
10
What can increases the proportion of new alleles
Mutations
Migrations
11
What can increase mutant alleles
Non random mating
12
What are two forms of nonrandom mating
Assortative mating - of shared characteristics
Consanguinity - between relatives
13
Define natural selection
A gradual process by which biological traits become either more or less common in a population
14
What natural selection increases reproductive fitness the prevalence of adaptive traits and it gives a heterozygote advantage
Postive selection
15
What does negative selection reduce
reproductive fitness
prevalence of traits
reduction of mutant allele
16
Give 3 examples of heterozygous advantages and there resistances
sickle cell anaemia - malaria
cystic fibrosis - cholera/typhoid
Glucose 6 phosphate dehydrogenase deficiency - malaria
17
What can small population cause
genetic drift
founder effect
18
Define genetic drift
Statistical drift of gene frequencies due to chance or random events leading to the variation in the relative frequency of different genotypes in a small population
19
Define founder effect
The reduction in genetic variation that results when a small subset of a large population is used to establish a new colony
20
What is the result of the founder effect
limits genetic variation
21
What is applications of HWE
Useful for calculating risk in genetic counselling
Useful for planning population based carrier screening programmes
22
To calculate a carrier frequency what do you need to find out of ratio p² : 2pq : q²
2pq - heterozygote
23