Module 1 - Part 1

Question 1

4 ways to classify mutations

Answer 1

• whether they’re heritable
• how they arise
• effects on gene function
• the type of mutation

Question 2

Mutations are an important source of…

Answer 2

genetic diversity

Question 3

Wildtype alleles

Answer 3

more abundant allele

Question 4

Mutant alleles

Answer 4

more rare allele

Question 5

Spontaneous mutation

Answer 5

occur randomly with no known cause
- arise in spontaneous manner (replication error/transposons)
- occur infrequently compared to induced mutations

Question 6

Induced mutation

Answer 6

arise due to exposure to physical & chemical mutagenic agents, radiation
- increase freq of mutation rates several fold compared to spontaneous mutations

Question 7

Loss of function mutation

Answer 7

Reduces or destroys protein function
- can be dominent (hapo-insufficient)
- can be recessive (hapo-sufficient)

Question 8

2 types of LOF mutations

Answer 8

1. null (amorphic): complete loss of protein function
2. hypomorphic: incomplete; reduced activity

Question 9

Gain of function mutation

Answer 9

Increased activity or new function; wrong place wrong time
- almost always dominant

Question 10

3 types of GOF mutations

Answer 10

1. hypermorphic: more activity/more efficient protein
2. neomorphic: generates a new function
3. antimorphic: prevents normal protein from performing normal homeostatic function

Question 11

Tp53

Answer 11

• tumour protein 53 (important tumour suppressor)
• a transcription factor that functions as the gatekeeper of cell cycle progression
• p53 arrests cell cycle if there’s DNA damage

Question 12

p53 in normal homeostasis

Answer 12

• allow cells to repair damage
  turn on
• apoptosis genes
• DNA repair genes
  turn off
• cell cycle genes
  DECREASED proliferation

Question 13

p53 LOF (null)

Answer 13

• INCREASED proliferation
• in cancer, most p53 LOF mutation occur in DBD
  (dna binding domain)

Question 14

p53 GOF

Answer 14

• anti-morphic
• surpasses the function of WT p53
• exhibit same phenotypes as p53 null cells
• reduced expression apoptosis/repair
• up-regulation of cell cycle genes

Question 15

Types of mutations

Answer 15

1. single nucleotide (point mutation)/ few bp
2. chromosomal rearrangements
3. changes in chromosome number (aneuploidy)

Question 16

Point mutations

Answer 16

• change in DNA seq without changing the open reading frame
• single base pair substitutions

Question 17

3 types of point mutations

Answer 17

1. nonsense: code for a STOP codon (truncate protein)
2. missense: code for a different amino acid resulting in non func protein/protein w different func
3. silent: code for the same or different amino acid but there’s no func change in protein

Question 18

central dogma

Answer 18

• specified by the genetic code
• genetic code: set of nucleotide triplicate that code for aa or translate stop signal