DNA mutations Quiz 5

Question 1

proofreading

Normal error rate
nutD mutant error rate

Answer 1

repairs mutations due to tautomeric shifts that lead to mismatched bases.
Pol III backs up and removes wrong base
Normal error rate is 1 x 10^-10
mutD mutant error rate is 1 x 10^-6

Question 2

UV damage

Answer 2

•Pyrimidine dimers 
-caused by uv radiation 
-two pyrimidines covalently attach to each other 
-causes major helix disruption 
2 ways to repair

Question 3

1. repair by photolyase

Answer 3

• photolyase catalyzes reversal of pyrimidine dimers

* uses light energy

Question 4

2. nucleotide excision repair

Answer 4

• targets major helix disruptions
• works well on UV repair
• damaged DNA removed from helix

Question 5

steps for nucleotide excision

Answer 5

uvrAB complex binds to damage, cuts, poly I repairs, ligase repairs gap

Question 6

describe exp that would test if a bacterium had a photolyase enzyme

Answer 6

damage bacteria, put in light and nonlight envir, plot

Question 7

antibiotic resistance mechanisms

Answer 7

1. destroy antibiotic. many bacteria secret b lactamase (exo enzyme)
2. modifying antibiotic. cant interfere w ribosome
3. altering target. ie transpeptidase
4. drug efflux. pumps drugs out from cell. mdr exporter.