Lecture 6

Question 1

DNA glycolyses

Answer 1

Remove base rather than entire nucleotide

Resulting cleavage = AP site

1 type per base

Question 2

Uracil glycosylase

Answer 2

Removes uracil that results form spontaneous deamination of cytosine

Ss dna has higher rate if deamination of C

Question 3

UNG

Answer 3

Uracil glycosylase that elimantes U paired with A instead of Ts

Question 4

HsMUG1

Answer 4

Uracil Glycosylase that removes uracil of single stranded dna during replication

Question 5

Base excision repair pathway

Answer 5

Recognizes mismatch
Cleaves phosphodiester backbone
DNA pol I fixes strand
Ligase seals nick

Question 6

Nucleotide excision repair

Answer 6

Key to fixing helical distortions

Use Excinucelases (double snip)

DNA fragment released

DNA pol and ligase fill in

Question 7

Excinucleases in E. coli vs humans

Answer 7

E Coli
5th 3’
8th 5’

Humans
6th 3’
22nd 5’

Question 8

Pyrimidine dimers

Answer 8

Uv induced damage

Question 9

Direct repair

Answer 9

Photolyases
Absorb energy - pass to FADH - donates electron radical to Pyrimide dimer - electrons rearrangement - radical back to fadh