Lecture 9 - DNA damage and repair Flashcards

1
Q

name the 5 sources of DNA damage

A

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

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2
Q

when UV light damages DNA what happens to pyrimidine dimers?

A

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

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3
Q

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

A

solar
cosmic
terrestrial radionuclides (C14, H3)

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4
Q

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

A

8-oxodG

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5
Q

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

A

double bond O coming off pentagon

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

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6
Q

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

A

uranium in granite

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7
Q

name 5 sources of environmental mutagens

A

food, water, air borne, smoking, industrial

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8
Q

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

A

acrylamide, aflatoxin

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9
Q

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

A

car exhaust fumes, polycyclic aromatic hydrocarbons

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10
Q

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

A

heavy metals

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11
Q

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

A

dried fruits, corn, peanuts, grain

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12
Q

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

A

true - can cause liver cancer

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13
Q

acrylamide in food comes from what?

A

high temp cooking - from asparagine

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14
Q

name the 5 DNA repair mechanisms

A

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

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15
Q

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

A

direct reversal

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16
Q

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

A

A/C - ABH2/ABH3
G - MGMT

17
Q

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

A

06methylguanine

methyl group

18
Q

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

A

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

19
Q

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

A

nucleotide excision repair

20
Q

how many bases does NER remove?

21
Q

what are the 2 types of NER?

A

global genome and txn coupled

22
Q

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

A

cockayne syndrome

23
Q

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

A

base excision repair

24
Q

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

A

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

25
in base excision repair damage recognition is done by which DNA enzyme?
DNA glycosylase
26
which DNA glycosylase recognises damage for 8-oxodG in base excision repair?
hOGG1
27
which DNA repair mechanism is the primary mechanism for recognition of DNA mismatches and chemically induced damage arising during DNA replication?
mismatch repair
28
mutations in which DNA repair pathway are associated with familial colon cancer? what are the mutations?
mismatch repair, MLH1 and MSH2
29
name the 2 types of DSB DNA repair?
NHEJ and homologous recombination
30
NHEJ and homologous recombination repair double strand breaks that arise during which 3 things?
replication, from chemical damage and ionising radiation
31
what are the 4 alternatives to DNA repair mechanisms?
activation of signalling systems, cell cycle arrest, apoptosis and senescence
32