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Intro To Biochem: DNA-Msap Wk 1 > Origin Of replication > Flashcards

Origin Of replication Flashcards

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1
Q

What is the typical shape of prokaryote genomes?

A

Circular

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2
Q

How many origins of replication (ORI) do prokaryote genomes usually contain?

A

One

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3
Q

What is the function of the ORI in DNA replication?

A

It is the site where DNA replication is initiated

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4
Q

In E. coli, how is the replication process regulated?

A

Only at the point of initiation

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5
Q

What happens once the replication fork is established in E. coli?

A

Replication proceeds until completion

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6
Q

What are the products of DNA replication in prokaryotes?

A

Two circular daughter DNA molecules

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7
Q

Fill in the blank: DNA replication is initiated at distinct sites called _______.

A

origins of replication (ORI)

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8
Q

What is OriC?

A

OriC is the origin of replication in E. coli, with a length of 245 bp.

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9
Q

What are the important sequences found in OriC?

A

OriC contains two important sequences: 13-nucleotide sequences and 9-nucleotide sequences.

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10
Q

How many 13-nucleotide sequences are present in OriC?

A

There are three 13-nucleotide sequences in tandem array.

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11
Q

How many 9-nucleotide sequences are present in OriC?

A

There are four 9-nucleotide sequences present.

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12
Q

What is the significance of the 9-nucleotide sequences in OriC?

A

The 9-nucleotide sequences serve as binding sites for DnaA protein.

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13
Q

What is the consensus sequence of the tandem array of 13-mer sequences?

A

The consensus sequence is GATCTNTTNTTTT.

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14
Q

What is the characteristic of the 13-mer tandem sequences at the Ori?

A

They are A-T rich.

Bonding between A-T is weaker than G-C, facilitating easier melting and strand separation of the DNA molecule at this region.

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15
Q

What initiates the process of replication at the Ori?

A

DnaA initiator proteins bind to the 9-nucleotide regions.

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16
Q

What is the consensus sequence for the binding sites of DnaA protein?

A

GATCTNTTNTTTT.

17
Q

What is the length of the oriC region?

A

245 bp.

18
Q

What are the 9-mers in E.coli OriC?

A

The 9-mers are specific DNA sequences at the origin of replication where initiator proteins bind.

19
Q

What role does DnaA play in the initiation of replication?

A

DnaA is an initiator protein that binds to the 9-mers at the origin.

20
Q

What is the function of DnaC?

A

DnaC is a helicase inhibitor protein that delivers helicase (DnaB) to the template.

21
Q

What is the role of ATP in the initiation of replication?

A

ATP is required for the binding of DnaA and the formation of the initial complex.

22
Q

What is DnaB?

A

DnaB is a helicase that unwinds the DNA during replication.

23
Q

What occurs at the 13-mer sequences during replication initiation?

A

Strand separation occurs at the region of the 13-mer sequences.

24
Q

What is the prepriming complex?

A

The prepriming complex is formed when DnaB clamps around each single strand of DNA.

25
Q

How does helicase unwind the DNA?

A

Helicase unwinds the DNA in opposite directions away from the origin.

26
Q

What is the role of initiator proteins (DnaA protein) in DNA replication?

A

Initiator proteins bind to the origin of replication and break hydrogen bonds between bases.

27
Q

What is the function of helicase inhibitor (DnaC)?

A

DnaC delivers helicase to the DNA template.

28
Q

What does DNA helicase (DnaB) do during replication?

A

DnaB opens the helix and binds primase to form the primosome protein complex.

29
Q

What is the role of single stranded binding protein (ssb)?

A

ssb binds to single stranded DNA in the replication bubble and prevents it from re-annealing or forming secondary structure.

30
Q

What is the primosome?

A

The primosome is a protein complex formed by helicase and primase.

31
Q

What does ‘oric’ refer to in DNA replication?

A

Oric refers to the origin of replication in prokaryotes.

32
Q

What components are involved in the pre-primosome complex?

A

The pre-primosome complex includes DnaA, DnaB, and primase.

33
Q

Describe the difference between a leading dna strand and a lagging dna strand.

A

Leading : continuous in the direction of the replication fork
Lagging: discontinuous in the opposite direction of the fork

34
Q

Why are Okazaki fragments, formed?

A

They are synthesized from the discontinuous lagging strand. DNA polymerase must elongate from 5’ to 3’ direction. It needs enough 3’ to be exposed to do so. Okazaki fragments continue to help the elongation of 3’ end , then they are lysed together(Ligase)

Intro To Biochem: DNA-Msap Wk 1 (4 decks)

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