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Flashcards in Estimating Risk of Inherited Disease Deck (38)
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1

What is fitness?

Relative ability of organism to survive (long enough) to pass on their genes

2

What can affect fitness?

Alleles

3

What are the 3 different kinds of alleles that can affect fitness?

Neutral allele (not at all in most cases)

Deleterious allele (sometimes decreases)

Advantageous allele (rarely decreases)

4

What is an allele?

A variant form of a gene

5

What is just an important as alleles for the fitness of human beings?

A child being brought up by family members and society

6

What is selective pressure?

Any phenomena which alters the behaiviour and fitness of living organisms within a given environment

7

What happens if selective pressure changes?

Importance of different alleles may change

8

What are the different kinds of genes that can become mutates?

Recessive genes

Dominant and X linked genes

9

What are some of the few noticable disease of recessive genes?

Sickle cell disease

Thalassaemia

10

When do recessive genes affect carriers?

When it is associated with selective pressure, such as malaria resistance

11

What is a de novo mutation?

A genetic alteration that is present for the first time in one family member as a result of a mutation

12

What are de novo mutations common in?

Dominant disorder, especially where the disease reduces reproductive fitness

13

How are genotype frequencies worked out?

People: 800AA + 190Aa + 10aa

 

AA = 800/1000 = 0.8

Aa = 190/1000 = 0.19

aa = 10/1000 = 0.01

14

How is the allele frequency worked out?

People: 800AA + 190Aa + 10aa

Alleles: 1600A + (190A + 190a) + 20a = 2000 in total

Frequency of A (p) = (1600 + 190) / 2000 = 0.9

Frequency of a (q) = (190 + 20) / 2000 = 0.1

15

What will p + q always equal?

1

16

What expression describes first generation genotype and allele frequencies?

Genotype: AA:Aa:aa = p2:2pq:q2

Allele: A:a = p:q

17

What can you say about relavent frequencies through generations?

Remain constant

18

What does the Hardy-Weinberg Equilbrium (HWE) state?

Allele frequencies remain constant generation to generation and so do relative proportions of genotype frequency

19

What are the assumptions underlying the Hardy-Weinberg Equilbrium?

Mutations 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

20

21

What do mutations increase the proportion of?

New alleles

22

What does introduction of new alleles as a result of migration lead to?

New gene frequency

23

What does non-random mating lead to?

Increase in mutant alleles, increasing the proporation of affected homozygotes

24

What are the 2 kinds of non-random mating?

Assortive mating (choosing new partners due to shared characteristics)

Consanguinity mating (marriage between close blood relatives)

25

What is assortive mating?

Choosing of partners due to shared characteristics

26

What is consanguinity mating?

Marriage between close blood relatives

27

What are homozygotes?

Individual having two identical alleles of a particular gene

28

What are heterozygotes?

Individual having two different alleles of a particular gene

29

What is the founder effect?

Loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population

30

What are the different kinds of natural selection?

Positive selection

Negative selection