RNA Proofreading

[MedPR]

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Unlike DNA Polymerase III (?), RNA Polymerase doesn't have a proofreading mechanism. Why isn't that a problem? I think EK explained it, but I can't find it in there.

 

[ljc]

I think I remember hearing this somewhere in AO, but couldn't find it on a quick speed through. The only thing I could find was the fact that RNA has a half-life of only 30 minutes, which might be relevant.

I'll give it another, longer, listen later as now I'm curious.

Edit: Found it, though it doesn't answer your question: "Transcription is much slower than replication and produces far more errors because unlike replication, there is no proof-reading and repair system for transcription. Transcription is also the most common point of regulation..."
This is in AO, Bio Lecture 2, Track name "RNA", @1:33

 

[MT Headed]

It isn't a problem because one DNA can be used as a template to make a lot of RNA transcripts. If a few of them are broken, the odds are it would just lead to a broken protein here and there, and not some supervirus.

The cell is probably transcribing in response to some event (like low glucose). So if it creates some broken proteins that are incapable of relieving the stress, then the cell will likely keep transcribing until good rna is made, functional proteins are created, and the stress is relieved.

Apparently this solution is good enough, and the alternative of proofreading rna hasn't generated a significant selective advantage.

 

[Pisiform]

Mainly because RNA is a transient molecule, it is being made, used and degraded quite often so there is no point in the proof reading mechanism similar to DNA pol.

 

[MedPR]

I think I remember hearing this somewhere in AO, but couldn't find it on a quick speed through. The only thing I could find was the fact that RNA has a half-life of only 30 minutes, which might be relevant.

I'll give it another, longer, listen later as now I'm curious.

Edit: Found it, though it doesn't answer your question: "Transcription is much slower than replication and produces far more errors because unlike replication, there is no proof-reading and repair system for transcription. Transcription is also the most common point of regulation..."
This is in AO, Bio Lecture 2, Track name "RNA", @1:33

I didn't figure out what "AO" was until that last line 🙂 I think I heard it in there too. Thank you.

It isn't a problem because one DNA can be used as a template to make a lot of RNA transcripts. If a few of them are broken, the odds are it would just lead to a broken protein here and there, and not some supervirus.

The cell is probably transcribing in response to some event (like low glucose). So if it creates some broken proteins that are incapable of relieving the stress, then the cell will likely keep transcribing until good rna is made, functional proteins are created, and the stress is relieved.

Apparently this solution is good enough, and the alternative of proofreading rna hasn't generated a significant selective advantage.

That makes sense, I hadn't even thought of that before. Thank you.

Mainly because RNA is a transient molecule, it is being made, used and degraded quite often so there is no point in the proof reading mechanism similar to DNA pol.

I think this is exactly what I read (or heard) in EK! Thanks again.