BER

Question 1

What are the 6 types of DNA repair?

Answer 1

6 types of repair 1. direct reversal 2. nucoeitde excision repair 3. mismatch repair 4. nonhomolougs end joining 5. recombination repair 6. base excision reaper

Question 2

In general, what are the types of BER lesions

Answer 2

small non helix distorting

Question 3

In gneral, what are the types of NER lesions

Answer 3

bulky helix distorting lesions

Question 4

What are the specific types of lesions that BER repairs

Answer 4

oxidized bases (8-oxoG, FAPY-A, FAPYG),
alkylated bases: 3-methyladenine, 7-methylguanosine
deaminated bases: hypoxnthine (adenine) uracil what

Question 5

direct reversal

Answer 5

chemical reversal of damaged bases

ex. UV radation generated prymididine drimers

Question 6

nucleotide excision repair

Answer 6

removes bulky helix distorting lesions

Question 7

mismatch repair

Answer 7

corrects errors made by DNA ploymerases during replcation and small insertaion/deltion loops in daughter DNA

Question 8

non-homologous end joining

Answer 8

. break ends are directly ligated without the need for a homologous template,

Question 9

recombination repair

Answer 9

correction of doulbe stranded breaks and corrections of lesions that cannot be reapired any other way

Question 10

base exicision repair

Answer 10

non-helix distorting lesions

Question 11

glycoslyases

Answer 11

cleaves the N-glycosidic bond between the base and the deoxyribose with a nucelophile attack of the C1 make an abasic site (mono) or AP site (bifunctional

Question 12

Mono vs. bifunctional

Glycosylase active groups in mechanism

Answer 12

mono- nucleophile is a water molecule

bi- active amine to generate a schiff base protein-DNA intermediate,

Question 13

Bifunctional glycosylases beta vs. beta delta elimination

Answer 13

beta - uses beta elimination to cleave the phosphodiester bond to make a phosphor-alpha,beta unsaturated aldehyde (PUA)
beta,detla- has two sequenal elmination steps and generates a 5’ PO4 group

Question 14

What are the 6 human glycoslayses that repair oxidized bases

Answer 14

OGG1, NTH1, nei endonucleases 8 (NEIL) 1,2,3

and mutY removes A incorrectly paired with 8-oxoG

Question 15

Role of AP endonuclease

Answer 15

after the base is removed, AP endonuclease generates a single strand break,
APE1 endonuclease account for 95% of AP site incsision

Ogg1 AP lyase activity, is debated

.

Question 16

Role of Pol beta

Answer 16

two distinct acitivites, can remove the