Lecture 9 - DNA damage and repair

Question 1

name the 5 sources of DNA damage

Answer 1

normal metabolism (free radicals)
UV light
ionising radiation
DNA synthesis
environmental mutagens

Question 2

when UV light damages DNA what happens to pyrimidine dimers?

Answer 2

they fuse, strands break, produces pyrimidine photoproducts (6-4)

Question 3

name 3 sources/types of ionising radiation that cause DNA damage

Answer 3

solar
cosmic
terrestrial radionuclides (C14, H3)

Question 4

which molecule, when unrepaired, mispairs with A and causes G-T transversion mutations in the generation of oxidative damage?

Answer 4

8-oxodG

Question 5

8-oxodG has which 2 groups coming off the 2 main rings (hexagon and pentagon)? which ring does each group come off?

Answer 5

double bond O coming off pentagon

NH2 coming off hexagon (as well as a double bond O)

Question 6

what is a major source of radon giving off natural exposure?

Answer 6

uranium in granite

Question 7

name 5 sources of environmental mutagens

Answer 7

food, water, air borne, smoking, industrial

Question 8

what are 2 examples of environmental mutagens causing DNA damage in food?

Answer 8

acrylamide, aflatoxin

Question 9

what are 2 examples of environmental mutagens causing DNA damage in the air?

Answer 9

car exhaust fumes, polycyclic aromatic hydrocarbons

Question 10

what is an example of environmental mutagen causing DNA damage in water?

Answer 10

heavy metals

Question 11

name 4 foods aflatoxin, an environmental mutagen causing DNA damage, is found in

Answer 11

dried fruits, corn, peanuts, grain

Question 12

true or false, aflatoxin is highly mutagenic, carcinogenic and hepatotoxic?

Answer 12

true - can cause liver cancer

Question 13

acrylamide in food comes from what?

Answer 13

high temp cooking - from asparagine

Question 14

name the 5 DNA repair mechanisms

Answer 14

direct reversal, NER, BER, mismatch repair, DSB repair

Question 15

which DNA repair mechanism, when it involves photolyase, is not found in humans?

Answer 15

direct reversal

Question 16

in direct reversal DNA repair the methylation of adenine and cytosine is done by what? the methylation of guanine is done by what?

Answer 16

A/C - ABH2/ABH3
G - MGMT

Question 17

In direct reversal of DNA damage, what is specifically repaired? which functional group is transferred to it?

Answer 17

06methylguanine

methyl group

Question 18

direct reversal of DNA damage is used when damage sources are which 3 things?

Answer 18

exogenous alkylating agents, normal metabolites and therapeutic exposure (chemo)

Question 19

which method of DNA damage repair is the primary mechanism for repair of UV induced or chemical induced damage?

Answer 19

nucleotide excision repair

Question 20

how many bases does NER remove?

Answer 20

24-29

Question 21

what are the 2 types of NER?

Answer 21

global genome and txn coupled

Question 22

which progeria syndrome is a result of transcription coupled NER repair failure?

Answer 22

cockayne syndrome

Question 23

which mechanism of DNA repair is the main mechanism for repair of oxidative damage, deamination, depyrimidation?

Answer 23

base excision repair

Question 24

in base excision repair there are two types what are they? how many bases do they repair each

Answer 24

short patch (1bp) and long patch (2-12bp)

Question 25

in base excision repair damage recognition is done by which DNA enzyme?

Answer 25

DNA glycosylase

Question 26

which DNA glycosylase recognises damage for 8-oxodG in base excision repair?

Answer 26

hOGG1

Question 27

which DNA repair mechanism is the primary mechanism for recognition of DNA
mismatches and chemically induced damage arising during DNA replication?

Answer 27

mismatch repair

Question 28

mutations in which DNA repair pathway are associated with
familial colon cancer? what are the mutations?

Answer 28

mismatch repair, MLH1 and MSH2

Question 29

name the 2 types of DSB DNA repair?

Answer 29

NHEJ and homologous recombination

Question 30

NHEJ and homologous recombination repair double strand breaks that arise during which 3 things?

Answer 30

replication, from chemical damage and ionising radiation

Question 31

what are the 4 alternatives to DNA repair mechanisms?

Answer 31

activation of signalling systems, cell cycle arrest, apoptosis and senescence