Questions about DNA Replication: RNA Primer, 3' to 5', TRNA

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Discussion Overview

The discussion revolves around the mechanisms of DNA replication, specifically focusing on the roles of RNA primers, the significance of the 3' to 5' directionality, and the synthesis of tRNA. Participants explore these concepts through questions and explanations, aiming to clarify their understanding of the processes involved in DNA and RNA synthesis.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants explain that the RNA primer is essential for DNA polymerase to initiate replication, as it provides a starting point for nucleotide attachment.
  • There is a discussion about the 3' to 5' directionality, with some participants noting that DNA polymerase moves from the 3' end to the 5' end during synthesis.
  • Participants mention that tRNA is synthesized by RNA polymerase during transcription, although there is uncertainty about the specifics of this process.
  • One participant questions why RNA primers are used instead of DNA, suggesting that the presence of the 3' OH end in RNA may play a role in this choice.
  • Another participant states that DNA polymerases require a 3' OH end to function, while RNA polymerases do not have this requirement.

Areas of Agreement / Disagreement

Participants express various viewpoints on the role of RNA primers and the directionality of DNA synthesis. There is no consensus on the specifics of tRNA synthesis, and some questions remain unresolved regarding the reasons for using RNA primers over DNA.

Contextual Notes

Some claims about the mechanisms of RNA and DNA synthesis depend on specific definitions and may not fully address the complexities involved. The discussion includes assumptions about the roles of different polymerases and the nature of the RNA primer.

Who May Find This Useful

This discussion may be of interest to students or individuals seeking to understand the biochemical processes of DNA replication and RNA synthesis, as well as those curious about the distinctions between RNA and DNA functions.

Dual Op Amp
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I have a question, I saw many animations of DNA replication. But there's a couple of questions I don't understand.
1. What is the difference between RNA primer and DNA?
2. When it says 3' to 5', what's that?
3. Where is TRNA made?
 
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Dual Op Amp said:
1. What is the difference between RNA primer and DNA?

The RNA primer is there to allow the polymerase to initiate replication. The primer is a short sequence and it is complementary to the parental strand. The RNA primer is sequenced by RNA primase.

Dual Op Amp said:
2. When it says 3' to 5', what's that?

It has to do with the DNA molecule. Look at the following picture
http://www.colorado.edu/MCDB/MCDB1150/ohd/dnamolecules.JPG
You see how the each nucleotides are attached. So when the the DNA polymerase is moving along it goes from the 3' end to the 5' site.

Dual Op Amp said:
3. Where is TRNA made?

tRNA is synthesis by a RNA polymerase in the same fashion than normal gene transcription. The strucuture is a normal feature of RNA and will fold without any help. The acceptor site the added but it not well known were the this is happening.
 
Last edited by a moderator:
1.) RNA primer is the thing that lays down the primers. Primers are a sequence of complementary RNA bases to which the DNA polymerase begins attaching its DNA nucleotides. This is done in both the leading and lagging strand, except the lagging strand has more primers.

2.) During RNA synthesis, the DNA strand is read in a 3' to 5' direction. 3' and 5' are two ends of the DNA strand.

3.) I'm not sure, but I think tRNA is made via RNA replication

A good site for info is www.wikipedia.org ; or you can just google this stuff.

EDIT: Sorry, I see someone has answered this already...
 
Last edited:
iansmith said:
The RNA primer is there to allow the polymerase to initiate replication. The primer is a short sequence and it is complementary to the parental strand. The RNA primer is sequenced by RNA primase.

Why RNA primer instead of DNA? does the OH in RNA molecule have something to do with this? Or what else can be determining?

Edit: maybe 3' OH end supplies the energy for synthesis?
 
DNA polimerases cannot work without a 3' OH end, but RNA polimerase can.
 

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