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Biochem exam 3 > DNA replication and repair > Flashcards

DNA replication and repair Flashcards

1
Q

DNA replication is conservative

A

False, semiconservative

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2
Q

The two DNA strands separate and each is copied so that the new DNA double helices contain _____ original strand and one newly synthesized strand

A

one

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3
Q

DNA replication is bidirectional. Replication proceeds in both directions from an origin of
replication

A

true

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4
Q

Replication is discontinuous. One of the two strands is copied discontinuously as a set of
fragments called Okazaki fragments which are then joined to form an intact strand.

A

false, semidiscontinuous

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5
Q

Replication is discontinuous. One of the two strands is copied discontinuously as a set of
fragments called Okazaki fragments which are then joined to form an intact strand.

A

false, semidiscontinuous

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6
Q

Okazaki fragments are longer in E. coli than in eukaryotes

A

true

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7
Q

semi conservative replication has _____ bonds which is an advantage to separating them.

A

weak

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8
Q

DNA polymerases in semi-discontinuous replication only synthesize DNA 3’-5’

A

false its 5-3

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9
Q

the two DNA strands of the double helix must be
in opposite directions

A

true

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10
Q

Replication is initiated in Prokaryotes, at the origin of replication (_____) by the binding of DnaA protein (the initiation factor), which separates the strands of the double helix.

A

oriC

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11
Q

in Prokaryotic replication, ______ protein (a helicase, or DNA-unwinding protein) binds to the separated strands and moves along the DNA, unwinding the double helix as it moves.

A

DnaB

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12
Q

in Prokaryotic replication, SSB (single-stranded DNA binding protein) prevents the ________ from
coming back together.

A

two strands

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13
Q

In prokaryotes, DNA ________ (DNA topoisomerase II) relieves stress in the helical DNA
structure caused by DNA unwinding

A

gyrase

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14
Q

elongation in Prokaryotic replication:
(a) DNA-unwinding proteins (DNA _______, gyrase)
(b) _________ enzyme, which synthesizes an RNA primer
needed for DNA replication.
(c) DNA polymerase ___ holoenzyme, which synthesizes the new DNA strands

A

a. helicase b. Primase C. III

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15
Q

Prokaryotic replication: DNA _________ ____ __________ consists of 10 different
subunits:
α ε θ τ β γ δ δ’ χ ψ

A

polymerase III holoenzyme

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16
Q

Prokaryotic replication: “Core” DNA polymerase III, which shows DNA
synthesizing activity in vitro, has 3 subunits:
α – ______________
ε – ______________
θ – ______________

A

α – polymerase activity
ε – proofreading activity (3-5 exonuclease)
θ – stimulates proofreading activity

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17
Q

Prokaryotic replication: The two bidirectional replication forks continue to move around the circular E. coli chromosome until they meet at a termination region (____ region), and replication is terminated

A

Ter

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18
Q

During termination in prokaryotic cells, a replication termination protein, ____,
is bound to Ter and helps to bring about termination

A

Tus

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19
Q

DNA in higher cells interacts with histone proteins to form nucleosomes and ___________, and these must be opened up to make the DNA accessible to replication proteins

A

chromatin fibers

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20
Q

in __________ replication, The beads-on-a string
nucleosome fiber (10 nm)
with DNA wrapped around
_______ proteins

A

eukaryotic and histone

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21
Q

A ______ fiber (30 nm)
produced by helical coiling
of the nucleosome fiber.

A

chromatin

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22
Q

A ______ fiber (30 nm)
produced by helical coiling
of the nucleosome fiber.

A

chromatin

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23
Q

Eukaryotic replication: Polymerase α—functions in the ______ of nuclear DNA replication.

A

initiation

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24
Q

Eukaryotic replication: Polymerase δ—principal DNA polymerase in eukaryotic DNA replication, works on ___________ ________.

A

Ozaki Fractions

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25
Q

Eukaryotic replication: WHICH POLYMERASES SYNTHESIZE MOST OF THE DNA

A

POL δ and POL ε

26
Q

Eukaryotic replication: Polymerase β—functions in DNA _______. Synthesizes short parts.

A

Repair

27
Q

Eukaryotic replication: Polymerase γ—DNA _________ enzyme of mitochondria.

A

Replicating

28
Q

Eukaryotic replication: ______—protein complex that binds to replication origins; essential for assembly of the pre-replicative complex. Brings in other proteins to bind to it

A

ORC

29
Q

Eukaryotic replication: _____proteins—eukaryotic helicases that unwind the double helix at replication origins and separate the DNA strands. learn more about this one

A

MCM

30
Q

Eukaryotic replication: ____ proteins—bring about the binding of MCM proteins to
replication origins

A

Cdc6

31
Q

Eukaryotic replication: ______ ____—kinase complex that initiates DNA replication by adding phosphate groups to ORC, MCM, and Cdc6 proteins

A

Cyclin CDK

32
Q

Eukaryotic replication: The ________ in the cyclin CDK have charges that fold and activate

A

phosphates

33
Q

Eukaryotic replication: A pre-replication complex is formed by the binding of Cdc6 and MCM proteins to the replication _____ region where ORC protein is bound.

A

origin

34
Q

Eukaryotic replication: cyclin–CDK then initiates DNA replication by adding _________ groups to ORC, MCM, and Cdc6 proteins.

A

phosphate

35
Q

Prokaryotic replication uses polymerase I and III

A

true

36
Q

Polymerase α will synthesize the _______ _____ and it also adds ________ ______ to start.

A

DNA nucleotides, RNA primer

37
Q

polymerase α contains 4 subunits Pol α1, Pol α2, and prime α1 and prime α2. Two will synthesize ______ and the other two will synthesize _______.

A

DNA and RNA primers

38
Q

Which polymerases in Eukaryotic cells have 3’-5’ proofreading exonuclease activity?

A

Polymerase δ and ε

38
Q

Which polymerases in Eukaryotic cells have 3’-5’ proofreading exonuclease activity?

A

Polymerase δ and ε

39
Q

which DNA polymerase does not help with replication in the eukaryotic cell?

A

Polymerase β

40
Q

Where do the polymerases replicate in the eukaryotic cell?

A

nucleus, except for γ, which does it in the mitochondria

41
Q

in eukaryotic cells the replication origin is called _____ while in prokaryotic cells it is called______.

A

ORC and oric

42
Q

MCM in eukaryotic cells are equivalent to _____ in prokaryotic cells.

A

DnaB

43
Q

go over telomeres- 1:20

A
44
Q

in eukaryotic replication: ___________ extends the 3’ end by adding TTAGGG repeats. this allows a DNA polymerase to extend the 5’ end.

A

Telomerase

45
Q

make flashcards on repair

A
46
Q

what enzyme removes the damaged
base by cleaving the glycosidic bond
between the base and deoxyribose

A

DNA glycosylase

47
Q

An ________ cleaves the backbone
to remove the deoxyribose and
phosphate group.

A

endonuclease

48
Q

an _________ removes a number of
additional nucleotide residues

A

exonuclease

49
Q

______________fills in the gap with a
patch of DNA.

A

DNA polymerase I

50
Q

___________ seals the deoxyribose-phosphate
backbone to create a continuous strand of
DNA

A

DNA ligase

51
Q

Corrects errors introduced when DNA is replicated. strands without a Methyl group are identified as incorrect.

A

Mismatch repair system

52
Q

Acts on single bases damaged by oxidation or other chemical modifications

A

Base excision repair

53
Q

Repairs larger regions of damaged DNA than base excision repair

A

Nucleotide excision repair

54
Q

DNA double-strand breaks caused by radiation or free radicals are repaired

A

Nonhomologous end-joining

55
Q

Uses homologous recombination to repair double-strand breaks that occur
during the cell division cycle

A

Recombination repair

56
Q

Chemically modified bases are directly repaired; an example is photolyase, an enzyme that repairs thymine dimers

A

Direct reversal repair systems

57
Q

in base excision repair, DNA _________ removes the damaged
base by cleaving the glycosidic bond between the base and deoxyribose

A

glycosylase

58
Q

in base excision repair, An ________ cleaves the backbone to remove the deoxyribose and
phosphate group.

A

endonuclease

59
Q

in base excision repair, An ___________ removes a number of
additional nucleotide residues

A

exonuclease

60
Q

in base excision repair, DNA ____________ fills in the gap with a patch of DNA

A

polymerase I

61
Q

in base excision repair, DNA ______ seals the deoxyribose-phosphate backbone to create a continuous strand of
DNA.

A

ligase

Biochem exam 3 (6 decks)

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