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Two questions about operon (transcription/translation)

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Two questions about operon (transcription/translation)

Postby farful » Mon Jul 27, 2009 5:33 pm

Let's deal with a bacteria only.

1. Suppose an operon was transcribed. When it gets translated, does each gene have its own translation intiation site (ribosomal binding site)? Or does it only have one (like it has one promoter).

2. rRNA (5s/16s/30s, with ITS1/ITS2) are found in a bacterial genome together. Does this mean they are transcribed in an operon, or are they transcribed separately?
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Postby plasmodesmata11 » Sun Aug 02, 2009 2:16 am

I can't help you on 2, but for the first one, each gene has its own individual initiation site. If it didn't, each protein would connect into the other, and you'd have some gigantic, probably nonfunctioning protein. When one ends, the next starts
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Postby MrMistery » Sun Aug 02, 2009 11:27 pm

plasmodesmata, your reasoning is good, unfortunately biology is not that theoretical. What you described indeed does happen: some policistronic prokaryotic mRNAs have a ribosome binding site (RBS) for each open reading frame. However, others do not: sometimes the last codon of one open reading frame coincides with the first codon of another open reading frame (think AUGA for example) so that when a ribosome has finished translating one reading frame it is in an ideal position to start translating the next reading frame, making it unnecessary to have another RBS. This phenomenon is known as translational coupling.

For #2 I honestly don't know the answer, but i think you should be able to find it via a google scholar search, seeing how it's just some information, not something about a process functioning.
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