The Nucleus and its Functional Domains

ID #1238

You said that mistakes in transcription and translation aren't as critical because RNAs are not heritable...can you explain this again?

Sure, I'm happy to clarify this. If there are no errors in the genome itself, it is still possible to make a mistake in transcription. RNA polymerases don't proofread like DNA polymerases, so these errors aren't that uncommon. But if you think about long-term effects on the organism that has made this transcriptional error, the "problem" isn't as bad as if the mistake was in the genome itself. For one, the cell will be making multiple copies of this RNA, and it is unlikely that it will make the same mistake again in the exact same place. And also, RNAs are quickly degraded, so there's a good chance that this "bad" copy of the RNA will be gone by the time the cell divides. With the exception of the RNA molecules that are still around when the cell divides (and will be degraded sometime after that), RNAs are not inherited molecules passed down from generation to generation. It's the DNA that is passed that way, and new RNAs are transcribed as needed. For both of these reasons, making an incorrect copy of an RNA molecule is not going to be as consequential as making a change in the genome, which is lasting and permanent.

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