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Dental Biochemistry Exam 1 > DNA Damage and Repair > Flashcards

DNA Damage and Repair Flashcards

1
Q

The chemical nature of DNA makes it highly susceptible to ______

A

damage

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2
Q

distortions to the shape of the DNA helix facilitates recognition of DNA _______

A

lesions

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3
Q

DNA replication is prone to ______ and enzymes can
accidentally remove or add a base (examples… ______ and ________)

A

error, cystic
fibrosis, Tay-Sachs disease

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4
Q

________ DNA damage are caused by environmental or external factors

A

exogenous

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5
Q

_______ DNA damage is caused by internal processes within the cell

A

endogenous

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6
Q

Cancer and aging are a
consequence of
unrepaired or faulty ______

A

DNA repair

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7
Q

DNA polymerase gama functions during DNA replication in ______

A

mitochondria

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8
Q

DNA polymerase delta functions in replication by synthesizing the ______ strand and helping with DNA ______

A

lagging, repair

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9
Q

DNA polymerase epsilon functions in replication by synthesizing the ______ strand

A

leading

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10
Q

cell cycle checkpoint proteins are an important factor in the consequences of ______

A

DNA damage

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11
Q

DNA damage will cause a delay in _______

A

cell cycle progression

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12
Q

check point 1 will prevent a cell from entering into ____ phase if its DNA contains damage

A

S

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13
Q

check point 2 will prevent a cell from entering
into _____ phase if there are breaks or damage sites in the DNA

A

M

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14
Q

_______ and _______ are caused by oxidation and alkylation of the DNA

A

single stranded breaks, oxidized bases

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15
Q

______ and ______ are caused by UV light and anti-tumor drugs

A

bulky lesions, cross links

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16
Q

mismatches in DNA is caused by ______

A

replication errors

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17
Q

_______ are caused by irradiation, anti-tumor drugs and replication fork collapse

A

double stranded breaks

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18
Q

________ is a type of spontaneous DNA damage that causes an unnatural DNA base change from C to U that will be carried over into DNA replication

A

deamination of cytosine

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19
Q

________ is a type of spontaneous DNA damage will cause a base change to thymine which will escape DNA repair

A

deamination of 5-methyl cytosine

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20
Q

_______ is a type of spontaneous DNA damage where the base of a nucleotide is cleaved causing the nucleotide to be missing a nitrogenous base

A

depurination

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21
Q

_______ is the addition of a methyl or ethyl group to DNA bases

A

alkylation

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22
Q

tobacco specific nitrosamines will be metabolized by the liver and lungs and will then base pair to DNA causing a base that is ______ which creates problems during ______

A

too bulky, DNA replication

23
Q

tobacco specific dimethylnitrosamine is a carcinogen that is metabolized by the liver which causes a methyl group to be transferred to _____ this _______ now base pairs with thymine causing a permanent A:T mutation

A

guanine, O6-methyl-gunaine

24
Q

smoking can cause many types of alkylated DNA including ________, _______, _______ crosslinking, and _______ crosslinking

A

monoalkylation, intercalation, interstrand, intrastrand

25
Q

DNA damage by oxidation targets guanine and creates a OxoG which basepairs with C but also basepairs with A causing a _______

A

mismatched pairing

26
Q

oxidation of aromatic polycyclic benzo[a]pyrene in cells causes covalent binding to _______ residues in DNA and interrupts H bonding in G-C pairs which forms ______

A

guanine, bulky adducts

27
Q

DNA damage by ___________ causes the formation of adjacent pyrimidine dimers, the formation of covalent dimers on the C=C double bonds and the defective base pairings stops replication and transcription

A

Ultraviolet UV irradiation

28
Q

blue light irradiation generates __________ and induces oxidative stress in oral tissues and the eyes however some oxidative stress is counteracted by antioxidants and DNA repair mechanisms

A

reactive oxidative species

29
Q

__________ are the most lethal types of DNA damage

A

double stranded breaks

30
Q

double stranded breaks are caused by ______ and ______

A

gamma irradiation, X-ray

31
Q

if double stranded breaks are left unrepaired, this can lead to the breakdown of ________ and ________ as well as interferes with DNA replication and transcription

A

chromosomes, chromosomal rearrangements

32
Q

the indirect effects of gamma irradiation and X-rays include production of _______ that cause single strand breaks and abasic sites

A

ROS

33
Q

the direct effects of gamma irradiation and X-rays include ______ and _______

A

single, double strand breaks

34
Q

Base excision repair repairs _____, ______, ______ and _______

A

Uracil, OxoG, O6-methyl-G, single strand breaks

35
Q

the steps of base excision repair include the removal and replacement of modified ______, DNA glycoslyase binds DNA and removes damaged ______, AP endonuclease nicks the _______ and DNA polymerase _______ the gap then ligase ______ the nicks

A

bases, base, backbone, fills in, seals

36
Q

nucleotide excision repair repairs _______ and ______ caused by chemicals

A

pyrimidine dimers, bulky adducts

37
Q

the steps of nucleotide excision repair include the scanning of DNA for damage, a pair of coordinated incisions by _______ on either side of the DNA strand carrying the lesion, ______ removes the single strand segment with the lesion, ________ will fill in the gaps and _____ will seal the gaps

A

DNA nucleases, helicase, DNA polymerase, ligase

38
Q

individuals with xeroderma pigmentosum are unable to perform ____—

A

nucleotide excision repair

39
Q

transcription coupled excision repair is nucleotide excision repair coupled with ______

A

RNA transcription

40
Q

transcription coupled excision repair ensures the transcribed DNA strand of an active gene is repaired faster, where RNA polymerase senses damage and _______ to trigger the recruitment of ______ protein to next recruit components of _____

A

stalls itself, CSB, NER

41
Q

direct repair refers to mechanisms that remove damage directly without ______ or ______ of segments of DNA

A

cutting, rearranging

42
Q

DNA photlyases are photoreactivated enzymes that use visible light to cleave ______ dimers

A

pyrimidine

43
Q

methyl transferases are adaptive response enzymes that transfer a _______ group from O6-guanine to a _______ residue within the protein

A

methyl, cysteine

44
Q

direct repair of pyrimidine dimers, not found in humans, uses _______ to cleave clyclobutane ring

A

DNA photolyase

45
Q

direct repair of O6-methylguanine uses _________ to bind and take away the added methyl group from guanine

A

methyltransferases

46
Q

double stranded breaks are repaired using __________, __________ and ________

A

homologous recombination, non-homologous end joining, alternative NHEJ

47
Q

double strand break repair repairs double strand breaks as well as _______, _____ and _____ strand crosslinks

A

single strand breaks, inter, intra

48
Q

homologous recombination uses the _______ and the _______ to repair the broken ends

A

intact sister chromatid, homologous chromosome

49
Q

BRCA1 and BRCA2 are critical for homologous recombination in recruiting specific _____ to bind to the broken ends

A

proteins

50
Q

homologous recombination is only available at ________

A

S and G2 phase before mitosis

51
Q

non-homologous end joining and alternative non-homologous end joining directly ______ broken ends, but DNA information is _____

A

ligates, lost

52
Q

lesion by-pass (translesion) DNA synthesis is used when a damaged nucleotide was not repaired before _______, a translesion DNA polymerase allows for DNA replication to continue but does _________ causing mutations and high error prone base pairing

A

DNA replication, not repair lesion

53
Q

mismatch repair mechanism corrects _______ in DNA that were caused by DNA polymerase

A

mismatched bases

54
Q

mismatch repair mechanism starts with cutting of the ________ synthesized DNA strand, excise the _______, resynthesize the DNA and ______ the patch to the continuous DNA strand

A

unmethylated most recently, mismatched base, ligate

Dental Biochemistry Exam 1 (10 decks)

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