DNA replication and repair Flashcards by Drew Meyer

DNA replication is conservative

False, semiconservative

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

one

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

true

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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.

false, semidiscontinuous

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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.

false, semidiscontinuous

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Okazaki fragments are longer in E. coli than in eukaryotes

true

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

weak

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

false its 5-3

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

true

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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.

oriC

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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.

DnaB

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

two strands

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

gyrase

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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. helicase b. Primase C. III

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

polymerase III holoenzyme

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

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

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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

Ter

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

Tus

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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

chromatin fibers

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

eukaryotic and histone

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

chromatin

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

chromatin

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

initiation

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

Ozaki Fractions

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Eukaryotic replication: WHICH POLYMERASES SYNTHESIZE MOST OF THE DNA

POL δ and POL ε

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

Repair

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

Replicating

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

ORC

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

MCM

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

Cdc6

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

Cyclin CDK

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

phosphates

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.

origin

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

phosphate

Prokaryotic replication uses polymerase I and III

true

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

DNA nucleotides, RNA primer

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

DNA and RNA primers

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

Polymerase δ and ε

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

Polymerase δ and ε

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

Polymerase β

Where do the polymerases replicate in the eukaryotic cell?

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

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

ORC and oric

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

DnaB

go over telomeres- 1:20

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

Telomerase

make flashcards on repair

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

DNA glycosylase

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

endonuclease

an _________ removes a number of additional nucleotide residues

exonuclease

______________fills in the gap with a patch of DNA.

DNA polymerase I

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

DNA ligase

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

Mismatch repair system

Acts on single bases damaged by oxidation or other chemical modifications

Base excision repair

Repairs larger regions of damaged DNA than base excision repair

Nucleotide excision repair

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

Nonhomologous end-joining

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

Recombination repair

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

Direct reversal repair systems

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

glycosylase

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

endonuclease

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

exonuclease

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

polymerase I

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

ligase