BIOL 303 DNA Replication vs Transcription

What is the ORI?

DNA Replication start site; initiator proteins bind here.

Promoter

Transcription start region; transcription machinery binds here.

DNA polymerase

DNA Replication; Enzymes that builds new DNA in the 5′ → 3′ direction.

RNA polymerase

Transcription; builds RNA 5′ → 3′ without a primer.

dNTPs vs. rNTPs

dNTPs build DNA; rNTPs build RNA.

Primase

Replication; makes RNA primers that provide a 3′-OH.

RNA primer

Provides the 3′-OH that DNA polymerase needs to begin DNA replication.

Are Promoters part of DNA Replication or Transcription?

Transcription; they lay down RNA code so that RNA polymerase can attach to the strand and begin transcription

Helicase

Replication; unwinds DNA at the replication fork.

Is it RNA Polymerase or DNA Polymerase in Transcription?

RNA Polymerase

Single-strand-binding proteins (SSBs)

Replication; stabilize exposed single-stranded DNA.

Is it DNA Polymerase or RNA Polymerase in DNA Replication?

DNA Polymerase

Topoisomerase

Replication; relieves torque ahead of the replication fork.

DNA ligase

Replication; seals nicks and joins Okazaki fragments.

Leading strand

Continuously synthesized in the 5′ → 3′ direction.

Lagging strand

Discontinuously synthesized 5′ → 3′ using Okazaki fragments.

Okazaki fragments

Short DNA fragments produced during lagging-strand replication.

Initiator protein vs. sigma factor

Initiator → ORI/replication; sigma → promoter/bacterial transcription.

Sigma factor

Bacterial transcription; helps RNA polymerase recognize the promoter.

True or False: RNA Polymerase requires a primer before attaching to the DNA strand and start transcribing.

False; DNA Polymerase needs a primer, not RNA polymerase

Core RNA polymerase + sigma factor

Bacterial RNA polymerase holoenzyme.

Template strand in transcription

DNA strand copied to make complementary, antiparallel RNA.

Is helicase part of DNA replication or Transcription?

DNA replication

What does helicase do?

Nontemplate strand

DNA strand not copied during transcription of that gene.

Transcription unit

Promoter → RNA-coding region → terminator.

Terminator

Region that signals the end of transcription.

Rho-dependent termination

Uses rho protein to terminate bacterial transcription.

Rho-independent termination

Uses an RNA hairpin followed by uracils; no rho protein required.

Telomerase

Replication; extends chromosome ends to address the end-replication problem.

Replication vs. transcription

Replication = DNA → DNA; transcription = DNA → RNA.

Primer requirement

Replication requires RNA primers; transcription does not require a primer.

5′ → 3′ synthesis

Both DNA replication and transcription synthesize new strands 5′ → 3′.

Promoter vs. ORI

Promoter starts transcription; ORI starts DNA replication.

Replication building blocks

dNTPs.

Transcription building blocks

rNTPs.

Replication main enzyme

DNA polymerase.

Transcription main enzyme

RNA polymerase.

Leading vs. lagging strand

Leading = continuous; lagging = discontinuous; both are synthesized 5′ → 3′.