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Molecules to Cells > DNA Replication > Flashcards

DNA Replication Flashcards

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Organic Chemistry 101 flashcards
1
Q

What are the four steps of DNA synthesis?

A
  1. Initiation
  2. Priming
  3. Synthesis
  4. Termination
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2
Q

How many initiation sites are there in prokaryotes?

A

1

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3
Q

Is prokaryotic synthesis unidirectional or bidirectional?

A

bidirectional

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4
Q

Why are AT rich repeats important for initiation?

A

They are less stable than native DNA and can open to form the replication bubble

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5
Q

What MUST come before DNA polymerase?

A

RNA primase!!

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6
Q

In what direction is DNA made?

A

5’ to 3’

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7
Q

What is the function of DNA pol III?

A

Replicative chain elongation

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8
Q

What is the function of DNA pol I?

A

Primer excision (nick translation) and DNA repair

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9
Q

Does DNA pol I or III have higher processivity?

A

Pol III

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10
Q

What does the beta subunit of Pol III do?

A

A sliding clamp that encircles DNA and holds the polymerase onto the DNA

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11
Q

What does the alpha subunit of Pol III do?

A

Polymerize DNA

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12
Q

What does the epsilon “ε” subunit of Pol III do?

A

Proof reading/ 3’ to 5’ exonuclease

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13
Q

How many Pol III complexes will you have?

A

2! One at each replication fork

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14
Q

On the leading strand DNA is synthesized in the _____ direction as the replication fork and on the lagging strand DNA is synthesized in the _______ direction as the rep fork.

A

Leading = same

Lagging = opposite

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15
Q

Single strand binding proteins protect open DNA on the _____ strand.

A

Lagging

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16
Q

What does the gamma complex do in DNA Pol III?

A

It loads the beta subunit clamp

17
Q

How are RNA primers removed from the lagging strand?

A

DNA Polymerase I in a process called Nick Translation

18
Q

How does Nick Translation work?

A

DNA Pol I uses 5’ to 3’ exonuclease activity to hydrolyze primers and simultaneously the 3’ end of the Okazaki fragment is extended by incorporation of dNTPs. The nick is then sealed by DNA ligase

19
Q

What enzyme joins all the okazaki fragments?

A

DNA ligase

20
Q

What is the final step of e. coli DNA synthesis?

A

Type II topoisomerase separates interlinking strands of the replicated circles and refolds the DNA into supercoils

21
Q

What does DNA polymerase alpha do in eukaryotic DNA?

A

Makes the RNA primer at both leading and lagging strand

22
Q

Rnase H is defective in Aicardi-Goutieres syndrome. What is Rnase H responsible for?

A

Removal of RNA primer during eukaryotic DNA replication

23
Q

What is the diagnostic feature of Aircardi-Goutieres syndrome?

A

INF alpha in CSF

24
Q

What is the electrostatic charge of the inside of the inside of the Pol III B-subunit?

A

Negative–has a low affinity for DNA and keeps from sticking

25
Q

What is the origin of replication called in prokaryotes and eukaryotes?

A

OriC

ARS–autonomous replicating sequences

26
Q

What binds the origin of replication and initiates replication in prokaryotes and eukaryotes?

A

dnaA complex

ORC–origin of replication complex

27
Q

What helicase is used in prokaryote and eukaryote DNA replication?

A

dnaB/dnaC complex

MCM–minichromosome maintenance proteins

28
Q

What stabilizes single stranded DNA in prokaryotes and eukaryotes?

A

SSB’s

RPA–replication protein A

29
Q

What increases the processivity DNA replication?

A

B-subunit of Pol III

PCNA-proliferating cell nuclear antigen–of DNA Pol delta 𝛿

30
Q

What serves as the clamp loader in DNA replication in prokaryotes and eukaryotes?

A

γ gamma subunit

RFC-replication factor C

31
Q

What makes the RNA primer in prokaryotes and eukaryotes?

A

dnaG

DNA Pol α alpha

32
Q

What removes the RNA primers in prokaryotes and eukaryotes?

A

DNA Pol I (nick translation)

Rnase H and FEN1 (flap endonuclease)

33
Q

What eukaryotic polymerase is responsible for synthesizing DNA on the leading strand?

A

DNA Pol ε epsilon

34
Q

What eukaryotic polymerase is responsible for synthesizing DNA on the lagging strand?

A

DNA Pol δ delta

35
Q

What eukaryotic polymerase is responsible for synthesizing mitochondrial DNA?

A

DNA Pol γ gamma

36
Q

What are the two components of telomerase?

A

hTERT–protein component–reverse transcriptase

hTR–RNA component–serves as template

37
Q

What type of structure stabilizes the binding of telomere-binding proteins?

A

D-loop-T-loop

38
Q

What is the difference between exonucleases and endonucleases?

A

Exo–cleave at the end of polynucleotide chain

End–cleave in the middle of polynucleotide chain

39
Q

Describe the structure of DNA polymerase III

A

Consists of a core enzyme (theta, sigma, alpha, beta, tau) and a gamma-complex clamp loader

Molecules to Cells (34 decks)

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