Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Genetics > DNA Repair > Flashcards

DNA Repair Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

factors that lead to DNA damage

A

UV light, chemicals, radiation, pH, smoking, basic chemistry of nucleic acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

short term consequences of DNA damage

A

reduced proliferation, altered gene expression, apoptosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

long term consequences of DNA damage

A

aging, diseases like cancer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

difference between DNA damage and DNA mutation

A

DNA damage becomes DNA mutation if the DNA replicates before there is a chance of repairing the damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

two types of mutation

A

spontaneous or induced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

induced mutation is due to

A

exposure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

two classes of spontaneous mutations

A

errors during replication (only happens in S phase of cell division)

spontaneous lesions (chemical changes that happen spontaneously when cell is resting)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

ability of certain chemicals to exist as a mixture of two interconvertible isomers

A

tautomerism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

thymine spends more time in which one of its isomeric phase

A

spends more time in its keto from than its enol form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what happens if replication occurs while thymine is in its enol form

A

its enol form pairs with G instead of pairing with A hence leading to a spontaneous mutation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

difference in values of DNA polymerase error rate vs. actual error rate

A

DNA pol rate = 1/100,000 bp

actual rate = 1/10,000,000bp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

characteristics of DNA pol that helps correct bp mistakes

A

DNA pol has a 3’ - 5’ exonuclease activity where it backs up and corrects mistakes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

defect in BLM gene and DNA helicase

A

Bloom Syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

BLM gene is needed for what

A

replication repair and recombination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

characteristics of bloom syndrome

A
  • smaller than average
  • narrow chin, prominent nose and ears
  • facial rash (pigment and dilated blood vessels) upon exposure to sun
  • often get diabetes and have neurological, lung and immune system deficiencies
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is going on with the chromosomes of those with Bloom Syndrome

A

chromosomal instabilities - lots of chromosomal breaks and sister chromatid exchanges
(higher chance of getting cancer)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

rare autosomal recessive disorder that has increased spontaneous chromosome breakage which is made worse by exposure to DNA cross linking agents

A

Fanconi anemia (associated with DNA repair)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

people with Fanconi anemia have an increased risk of what

A

neoplasia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Fanconi anemia is associated with how many genes

A

8 different genes - locus heterogenity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

distinguishing characteristic of Fanconi anemia

A

dislocated thumb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

common places for frameshift mutations

A

where there are base repeats

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

causes of frameshift mutation

A
  • slipping of DNA pol during replication of base repeats

- DNA loops and kinks at these points and one or more bases are not copied or copied twice

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

changes that occur in resting cell due to chemical nature of the DNA

A

spontaneous lesions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

types of spontaneous lesions

A

deamination, depurination, oxidative damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

most common type of spontaneous lesion

A

depurination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

mechanism of depurination

A

breaking of glycosidic bond between purine base and sugar and purine is lost but the backbone stays intact - if it persists –> mutation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

mechanism of deamination

A

amine group lost from cytosine and it forms uracil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

why is deamination easy to fix

A

easy to fix because DNA does not have uracil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what is the issue when deamination occurs in CpG islands

A

the cytosine are methylated there so 5 methyl cytosine would deaminate to thymidine –> now have T-G pair –> both of which are normal bases —> so would be repaired to TA or CG —> mutational hotspot made

30
Q

mutational hotspots include what

A

CpG islands where 5 methyl cytosine are present and places with repeated bases

31
Q

oxidative damage is a result of

A

production of reactive oxidative compounds due to oxidative metabolism

32
Q

how to prevent oxidative damage

A

you cannot …unless you stop breathing ha!

33
Q

problem with oxidative damage

A

it places oxygen on nucleotide bases making it able to pair with the wrong bases —> mispairing with A leading to possible transversion

34
Q

increase frequency of normal mutations

A

mutagens

35
Q

serious mutagens in our evironment

A
  • UV (from sun or tanning beds)
  • ionizing radiation (from space or the ground) • aflatoxin (from moldy grain)
  • benzene
  • formaldehyde
  • mustard gases
36
Q

not so serious mutagens in our environment

A
  • alcohol (acetaldehyde breakdown product) • barbequed hamburgers
  • cigarettes
  • anything fun
37
Q

gamma rays, x-rays, and radioactive particles are all

A

ionizing radiation

38
Q

where do we get most radiations from

A

the ground - terrestrial radiation

39
Q

ionizing mutation can cause extensive damage of DNA which includes

A

heritable mutations - pass it on to next generation (offspring)

40
Q

what happens to adjacent thymine residues in presence of UV light

A

form deleterious photoproducts such as thymine dimers/pyrimidine dimers –> 6-4 photoproduct (6-4PP) and cyclobutane pyrimidine dimers (CPD)

41
Q

what do thymine dimers/pyrimidine dimers do

A

interfere with normal pairing and block replication

42
Q

ways to fix DNA damage

A

nucleotide excision, base excision, mismatch repair

43
Q

which one of the mechanisms of fixing DNA damage is post replication repair

A

mismatch repair

44
Q

how are thymine/pyrimidine dimers repaired

A

nucleotide excision - removing a few base pairs (up to 30) around damaged site

45
Q

how are DNA damage by methylation or oxidation repaired

A

base excision - repairs a single or just a few of the damaged bases by removing it

46
Q

mechanism of excision repair

A

recognition of damage and removal of damaged base or bases around the damage using specific repair proteins

replacement of excised region using shared repair proteins

47
Q

what protein removes sugar phosphate from damaged DNA

A

endonucleases

48
Q

mutation in 9 different NER genes

A

Xeroderma Pigmentosum (AR)

49
Q

incidence of xeroderma pigmentosa is higher in what population

A

Japan

50
Q

characteristic of Xeroderma Pigmentosa

A

extreme sun sensitivity, freckled with hyperpigmented skin lesions, ocular tumors, conjunctivitis, DNA damage cumulative and irreversible

51
Q

protein that recognizes specific damaged bases in DNA

A

DNA glycosylases

52
Q

removes small repeats that tend to expand (triplet repeat disorders)

A

mismatch repair

53
Q

which one of the repair mechanisms show strand discrimination and how?

A

mismatch repair

due to methylation in prokaryotes
due to methylation and replication machinery in eukaryotes

54
Q

mismatch missed by proofreading is recognized by

A

MMR protein

55
Q

repair occurs in what phases in mismatch repair

A

S phase if missed by proofreading

or G2 when genome is scanned for errors

56
Q

result of mutations in genes encoding mismatch repair proteins (MSH2 or MLH1 and more)

A

hereditary nonpolyposis colon cancer

57
Q

hereditary nonpolyposis colon cancer results in

A

microsatellite instability - simple repetitive DNA sequences show size variability due to inaccurate replication

58
Q

A 25-year old male spends a lot time basking in the sun, and also in tanning beds. Which type of DNA damage occurs with this behavior?

A

pyrimidine/thymine dimer

59
Q

A 12 year old pediatric cancer patient is found
to have a germline mutation in a gene encoding a DNA helicase. He is relatively small for his age, and he develops a rash when exposed to sunlight. Which of the following is
contraindicated for the treatment of his cancer?

A

CT scan, x-rays, UV tanning bed, DNA damaging agents

60
Q

with this type of break, there is a high probability of loss of genetic material

A

double strand breaks

61
Q

two mechanisms for repairing double stranded break

A

non-homologous end joining (more common) and recombination repair (uses homologous chromosome hence less error than NHEJ)

62
Q

BRCA1 and BRCA2 are involved in what processes when DNA can’t be repaired

A

DNA repair and apoptosis

63
Q

higher risk of developing ovarian cancer with mutation in which protein

A

BRCA1 (55%)

64
Q

good outcome of errors in DNA/DNA damage

A

they allow for evolution

65
Q

which errors can result in cancer and aging

A

somatic errors

66
Q

which errors can result in genetic diseases visited on your descendants

A

germline errors

67
Q

DNA repair genes are susceptible to mutation which can result in

A

increased error rate and genome instability (bloom syndrome)

68
Q

defect in ATM - a serine threonine kinase that detects DNA damage and activates cell cycle arrest and DNA repair protein

A

ataxia telangiectasia

69
Q

ataxia telangiectasia affects

A

cerebellum (=ataxia), immune system, ocular telangiectasia

70
Q

ATM/ATR - mediated signaling pathway

A

genotoxic stress –> sensor proteins –> apical kinases –> signal relay proteins –> effector proteins –> responses

Genetics (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions