Estimating risk of inherited genetics Flashcards Preview

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Flashcards in Estimating risk of inherited genetics Deck (23)
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1
Q

Define fitness

A

means the relative ability of organisms to survive and pass on genes

2
Q

What effects fitness

A

alleles

3
Q

What do genotype frequencies calculate

A

How many genotypes in the population

4
Q

How do we calculate genotype frequency

A

the number of people with that genotype divided by the number of people overall

5
Q

What must an allele frequency always add up to

A

1

6
Q

What is the genotype frequency equation for

AA : Aa : aa

A

p2 : 2pq : q2

7
Q

What is the allele frequency of A:a

A

p:q

8
Q

What do the allele frequency and genotype frequency of the Hardy-Weinberg equilibrium prove to us

A

Relative frequencies always remain constant therefore dominant alleles don’t become more common

9
Q

What is an idea population that will fit withHardy-Weinberg equilibrium

A
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
Q

What can increases the proportion of new alleles

A

Mutations

Migrations

11
Q

What can increase mutant alleles

A

Non random mating

12
Q

What are two forms of nonrandom mating

A

Assortative mating - of shared characteristics

Consanguinity - between relatives

13
Q

Define natural selection

A

A gradual process by which biological traits become either more or less common in a population

14
Q

What natural selection increases reproductive fitness the prevalence of adaptive traits and it gives a heterozygote advantage

A

Postive selection

15
Q

What does negative selection reduce

A

reproductive fitness
prevalence of traits
reduction of mutant allele

16
Q

Give 3 examples of heterozygous advantages and there resistances

A

sickle cell anaemia - malaria
cystic fibrosis - cholera/typhoid
Glucose 6 phosphate dehydrogenase deficiency - malaria

17
Q

What can small population cause

A

genetic drift

founder effect

18
Q

Define genetic drift

A

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
Q

Define founder effect

A

The reduction in genetic variation that results when a small subset of a large population is used to establish a new colony

20
Q

What is the result of the founder effect

A

limits genetic variation

21
Q

What is applications of HWE

A

Useful for calculating risk in genetic counselling

Useful for planning population based carrier screening programmes

22
Q

To calculate a carrier frequency what do you need to find out of ratio p² : 2pq : q²

A

2pq - heterozygote

23
Q

How do you work out carrier frequency,

A
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

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