Assessment 1: Class 3

Question 1

Mutation

Answer 1

Change in DNA that is retained and passed on

Question 2

2 Types of Mutagens

Answer 2

Initiator and Promoter

Question 3

Intiator

Answer 3

Capable of making a change

Question 4

Promoter

Answer 4

Doesn’t damage DNA but sets up conditions that increase risk when combined with another factor

Question 5

How many mutations does it take for cancer to occur?

Answer 5

• 7 Mutations

- This can take decades to accumulate

Question 6

Different Types of Mutations (3)

Answer 6

• Point
• Frame Shifts
• Translocations

Question 7

Point Mutation

Answer 7

• Signal identity change (most common)
• Creates a bulge in the backbone
• Division creates mutant pairs (3 mistakes/38 cells)
  G A T T C C A → G A G T C C A (T in 1 changes to G in 2)
  C T A A G G T → C T A A G G T

Question 8

Frame Shifts

Answer 8

• Points being added (very rare) or lost (more potential damage than point)
• e.g. Fusion of two T’s (Thymine dimer)
  G A “T T” C C A → G A “T” C C A
  C T A A G G T → C T A A G G T
• Everything is fine until the point of fusion
• Everything is altered after fusion occurs

Question 9

Translocations

Answer 9

• Caused by x-rays or other high radiation exposures
• Bits and pieces of one chromosome attach to another
• Rearrangement of 3 at a time and flips the order
  G A ‘T T C’ C A → G A ‘C T T’ C A
  C T ‘A A G’ G T → C T ‘G A A’ G T
• Changing how it is read
• Most common between chromosomes 9 and 22
• Translocations between chromosomes often times result in frame shifts

Question 10

DNA Repair (4 Steps)

Answer 10

1. Detect it (proteins detect damage and sit down on the mutation)
2. Cut it out (endonuclease (inside DNA cut))
3. Fill it in (DNA polymerase)
4. Seal it (seal ligase)