Estimating Risk of Inherited Genetic Disease

Question 1

<p>What is fitness?</p>

Answer 1

<p>Relative ability of organism to survive (long enough) to pass on their genes</p>

Question 2

<p>What can affect fitness?</p>

Answer 2

<p>Alleles</p>

Question 3

<p>What are the 3 different kinds of alleles that can affect fitness?</p>

Answer 3

<p>Neutral allele (not at all in most cases)</p>

<p>Deleterious allele (sometimes decreases)</p>

<p>Advantageous allele (rarely decreases)</p>

Question 4

<p>What is an allele?</p>

Answer 4

<p>A variant form of a gene</p>

Question 5

<p>What is just an important as alleles for the fitness of human beings?</p>

Answer 5

<p>A child being brought up by family members and society</p>

Question 6

<p>What is selective pressure?</p>

Answer 6

<p>Any phenomena which alters the behaiviour and fitness of living organisms within a given environment</p>

Question 7

<p>What happens if selective pressure changes?</p>

Answer 7

<p>Importance of different alleles may change</p>

Question 8

<p>What are the different kinds of genes that can become mutates?</p>

Answer 8

<p>Recessive genes</p>

<p>Dominant and X linked genes</p>

Question 9

<p>What are some of the few noticable disease of recessive genes?</p>

Answer 9

<p>Sickle cell disease</p>

<p>Thalassaemia</p>

Question 10

<p>When do recessive genes affect carriers?</p>

Answer 10

<p>When it is associated with selective pressure, such as malaria resistance</p>

Question 11

<p>What is a de novo mutation?</p>

Answer 11

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

Question 12

<p>What are de novo mutations common in?</p>

Answer 12

<p>Dominant disorder, especially where the disease reduces reproductive fitness</p>

Question 13

<p>How are genotype frequencies worked out?</p>

Answer 13

<p>People: 800AA + 190Aa + 10aa</p>

<p></p>

<p>AA = 800/1000 = 0.8</p>

<p>Aa = 190/1000 = 0.19</p>

<p>aa = 10/1000 = 0.01</p>

Question 14

<p>How is the allele frequency worked out?</p>

Answer 14

<p>People: 800AA + 190Aa + 10aa</p>

<p>Alleles: 1600A + (190A + 190a) + 20a = 2000 in total</p>

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

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

Question 15

<p>What will p + q always equal?</p>

Answer 15

<p>1</p>

Question 16

<p>What expression describes first generation genotype and allele frequencies?</p>

Answer 16

<p>Genotype: AA:Aa:aa = p²:2pq:q²</p>

<p>Allele: A:a = p:q</p>

Question 17

<p>What can you say about relavent frequencies through generations?</p>

Answer 17

<p>Remain constant</p>

Question 18

<p>What does the Hardy-Weinberg Equilbrium (HWE) state?</p>

Answer 18

<p>Allele frequencies remain constant generation to generation and so do relative proportions of genotype frequency</p>

Question 19

<p>What are the assumptions underlying the Hardy-Weinberg Equilbrium?</p>

Answer 19

<p>Mutations can be ignored</p>

<p>Migration is negligible (no gene flow)</p>

<p>Mating is random</p>

<p>No selective pressure</p>

<p>Population size is large</p>

<p>Allele frequencies are equal in the sexes</p>

Question 20

<p>What do mutations increase the proportion of?</p>

Answer 20

<p>New alleles</p>

Question 21

<p>What does introduction of new alleles as a result of migration lead to?</p>

Answer 21

<p>New gene frequency</p>

Question 22

<p>What does non-random mating lead to?</p>

Answer 22

<p>Increase in mutant alleles, increasing the proporation of affected homozygotes</p>

Question 23

<p>What are the 2 kinds of non-random mating?</p>

Answer 23

<p>Assortive mating (choosing new partners due to shared characteristics)</p>

<p>Consanguinity mating (marriage between close blood relatives)</p>

Question 24

<p>What is assortive mating?</p>

Answer 24

<p>Choosing of partners due to shared characteristics</p>

Question 25

<p>What is consanguinity mating?</p>

Answer 25

<p>Marriage between close blood relatives</p>

Question 26

<p>What are homozygotes?</p>

Answer 26

<p>Individual having two identical alleles of a particular gene</p>

Question 27

<p>What are heterozygotes?</p>

Answer 27

<p>Individual having two different alleles of a particular gene</p>

Question 28

<p>What is the founder effect?</p>

Answer 28

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

Question 29

<p>What are the different kinds of natural selection?</p>

Answer 29

<p>Positive selection</p>

<p>Negative selection</p>

Question 30

<p>What does negative selection do?</p>

Answer 30

<p>Reduces reproductive fitness</p>

<p>Decreases prevalence</p>

<p>Leads to gradual reduction of mutant alleles</p>

Question 31

<p>What does positive selection lead to?</p>

Answer 31

<p>Increase reproductive fitness</p>

<p>Increases prevalence of adaptive traits</p>

<p>Heterozygote advantage</p>

Question 32

<p>What can a small population size lead to?</p>

Answer 32

<p>Genetic drift</p>

<p>Founder effect</p>

Question 33

<p>What is natural selection?</p>

Answer 33

<p>Gradual process by which biological trates become either more or less common in a population</p>

Question 34

<p>What are some heterozygote advantages?</p>

Answer 34

<p>Sickle celll anaemia against malaria</p>

<p>Thalassaemia against malaria</p>

<p>Tay Sachs against TB</p>

<p>Cystic fibrosis against cholera</p>

Question 35

<p>What is genetic drift?</p>

Answer 35

<p>Random fluctuations in one allele transmitted to high proportion of offspring by chance</p>

Question 36

<p>What are some examples of the founders effect?</p>

Answer 36

<p>Cystic fibrosis in the faroes</p>

<p>Diminant BRCA1 and BRCA2 in Poland</p>

Question 37

<p>What are some applications of the Hardy-Weinberg Equilbrium (HWE)?</p>

Answer 37

<p>Useful for calculating genetic risk in genetic counselling</p>

<p>Useful for planning population based carrier screening programmes</p>