RNA polymerase vs. DNA polymerase??

[unsung]

It's been a long time since genetics. I read the EK genetics chapter but am still unclear: so, for DNA replication, an RNA polymerase is needed to make an RNA primer ?

When is DNA polymerase used?

What is a primer?

How does that differ from a promoter?

I'm very confused, apparently.

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[andafoo]

Hey pal,

DNA Polymerase is a polymerase that synthesizes a DNA strand ... so it's used in DNA replication.

RNA Polymerase is not used to form the primer - that is primases job. RNA Pol is used during transcription to synthesize the mRNA strand.


EK does a decent job describing a primer. I believe it is in orange text on the right hand margin. Anyhow, the primer starts DNA Polymerase off during replication. Just like for PCR, the primer is required for elongation to begin.


How primers differ from promoters is pretty simple. Primer is RNA in the case of replication. Promoter is a segment of DNA preceding genes or an operon. The promoter indicates or signals the transcriptional machinery to begin transcribing.

 

[Christo1]

..

👍

And just for the sake of completion, RNA Pol is about 10x slower than DNA Pol. RNA Pol also does not have any proof reading capabilities, which isn't really a bad thing, for if a gene gets transcribed 100s of times, resulting in many good, translatable mRNA, then that 1 bad mRNA won't make a difference.