DNA Flashcards

1
Q

DnaB

A

helicase, ATP-dependent unwinding of DNA

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2
Q

DnaG

A

primase (RNA polymerase) synthesizes primers

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3
Q

TopA

A

topoisomerase, detangles DNA

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4
Q

PolA

A

DNA polymerase 1. replaces RNA primers

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5
Q

LigA

A

ligates 3’OH of strand with 5’P of okazaki fragments

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6
Q

DARS1 (site in the genome)

A

DnaA activation

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7
Q

DARS2 (site in the genome)

A

reactivation of DnaA. free ATP bind to DnaA and now DnaA has high affinity for the nucleotide binding site.
-Fis and IHF bind to DARS2 in order to facilitate and activate this exchange of ADP to ATP.

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8
Q

factors involved in replication initiation

A

HU, IHF, Fis

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9
Q

HU

A

nucleoid associated protein that helps destabilize double-stranded DNA at the origin.

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10
Q

IHF

A

integration host factor, bends DNA

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11
Q

Fis

A

factor for inversion stimulation. helps stabilize initial initiation complex.

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12
Q

where does DnaA bind in the OriC?

A

between the duplex unwinding element and the IHF binding site

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13
Q

SeqA-oriC regulates?

A

prevents binding of DnaA at the oriC. SeqA fxns when hemimethylated DNA is present. methylation occurs on the A of GATC motifs in the DNA.

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14
Q

ATP-DnaA regulates?

A

prevents dnaA gene transcription

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15
Q

steps for initiation

A
  1. DnaA is activated with ATP
  2. DnaA binds to DnaA binding box (between DUE and IBS) - DnaA oligomerizes
  3. DnaB is recruited
  4. DnaG is recruited
  5. DnaA is inactived and dissociates, priming by DnaG
  6. DNA polymerase III holoenzyme will bind and replication starts.
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16
Q

DNA polymerase I

A

removes primers and replaces them with nucleotides

17
Q

DNA polymerase III

A

has 3-5 exonuclease activity as proofreading

18
Q

Tus

A

binds to ter sequences
interferes with DnaB function.
(terminus utilization substance)

19
Q

regulation of DnaA-ATP

A
  1. ATP-DnaA inhibits its own transcription
  2. seqA inhibits ATP-DnaA from binding to the oriC
  3. datA hydrolyzes the ATP
20
Q

Negative controls - Dna replication

A
  1. ppGpp: shows up when the cells are low on energy (nutrient limitation). down regulates the DnaA in the cell
  2. Arc: senses O2 concentration and redox potential. binds to the TATA box (DUE) repressing replication
  3. Ici: binds at DUE region. present in cells in stationary phase growth, so replication is not initiated.