PoD - Genetics

Question 1

what are disease-associated mutations?

Answer 1

• mutation in the protein alters the protein function (non-functional or missing)
• mutation causes disease

Question 2

what are sickle cell disorders?

Answer 2

• abnormal HB gene
• causes sickling of RBCs
• v.painful, cold/dehydration/infections, jaundice
• more common in african, mediterranean, middle-eastern and indian individuals

Question 3

if two parents are carriers of a mutated gene, what is the likelihood of child getting disease?

Answer 3

• 25% chance of having disease
• 50% chance of being a carrier
• 25% chance of being unaffected

Question 4

if one parent is a carrier of a mutated gene, what is the likelihood of child getting disease?

Answer 4

• no offspring can have disease
• 50% chance of being a carrier
• 50% chance

Question 5

what is cystic fibrosis?

Answer 5

• a single gene disorder

- makes mucus thicker and more sticky

Question 6

what is autosomal dominant inheritance?

Answer 6

• only need one mutated gene to cause disease
• each child has 50% chance of inheriting mutation
• no skipped generations
• male to male transmission

Question 7

what is achondroplasia?

Answer 7

• achondroplasia is an inherited autosomal dominant condition
• shortening of limbs and body

Question 8

what is huntington’s disease?

Answer 8

• autosomal dominant condition

- neurodegenerative disorder

Question 9

what is duchenne’s muscular dystrophy?

Answer 9

• x-linked disorder
• can be fatal
• if father has duchenne’s gene and mother doesn’t, all daughter will carry gene, sons won’t
• if mother carries gene and father unaffected, 50% chance of son and daughters being affected

Question 10

mechanisms of non-mendelian inheritance

Answer 10

• sporadic de novo mutations
• incomplete penetrance - gene modifier/environmental trigger
• mitochondrial disease - maternal inheritance

Question 11

what is alleles & fitness?

Answer 11

• the relative ability of organisms to survive to pass on their genes

Question 12

how can alleles affect fitness?

Answer 12

• not at all in most cases (neutral)
• sometimes decrease fitness (deleterious)
• rarely increase fitness (advantageous)

Question 13

how can non-random mating impact population genetics?

Answer 13

• non-random mating leads to increase in mutant alleles
• seen in assortative mating (choosing partners due to shared characteristics), consanguinity (marriage between close blood relatives) or cultural marriage

Question 14

what is natural selection?

Answer 14

• a gradual process by which biological traits become more or less common in a population
• affect reproductive fitness, adaptive traits

Question 15

what is genetic drift?

Answer 15

• random fluctuation of one allele transmitted to high proportion of offspring by chance
• mutations are widespread and neutral

Question 16

what is the founder effect?

Answer 16

• reduction in genetic variation that results when a new colony is started by a few members if the original population