Estimating risk of inherited genetics Flashcards Preview

Medicine Term One > Estimating risk of inherited genetics > Flashcards

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

How do you work out carrier frequency,

well you calculate q from statistic
p+q= 1,
calculate p= 1-q,
Now you have p and q
2 x p x q
=2pq