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Gene expression

Genetics as it applies to evolution, molecular biology, and medical aspects.

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Gene expression

Postby bht » Wed Jun 15, 2005 11:28 am

Are there conditions for certain genes (prokaryotic) to be expressed, take for example the ampicillin resistant gene which produces the protein beta-lactamase. :?
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Postby canalon » Wed Jun 15, 2005 1:14 pm

Yes all the prokaryotic genes are not expressed all the time> Ther is gene regulation in bacteria too.

As for beta lactamase specifically it is hard to say. There are many deiffrent genes in many different bacteria in many diffrent kind of structures. Some are regulated, some are not. It is impossible to give a better answer.

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Postby MrMistery » Wed Jun 15, 2005 7:44 pm

From what i know, genes in bacteria is organised in operons, so there usually is some situation(even if only hypothetical) that the gene is not expressed
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Postby canalon » Wed Jun 15, 2005 9:10 pm

MrMistery wrote:From what i know, genes in bacteria is organised in operons, so there usually is some situation(even if only hypothetical) that the gene is not expressed


Not all genes are organized in operons, it would make microbiology uninteresting and too easy :lol:

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Postby MrMistery » Wed Jun 15, 2005 9:27 pm

Lol... thanks for letting me know. So what other way of organising genes are there in bacteria? What about inhibitors and gene expression in general?
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Postby canalon » Thu Jun 16, 2005 12:40 am

MrMistery wrote:Lol... thanks for letting me know. So what other way of organising genes are there in bacteria? What about inhibitors and gene expression in general?


An operon implies a highly organised physical grouping of genes involved in a single mechanism. Many other regulation system can be found, like:
- one promoter for many genes the closer to the promoter, the higher the transcription. This organisation can be seen in integrons, where gene order can easily be shuffled thanks to their cassette form
- specific promoter sequences. Some genes have sigma dependant transcription. Sigma being the name of a sub unit of the RNApolymerase acivated in case of some stress
- Regulatory pathways without the geographical grouping implied by the operon.

And I forget probably a good deal of things. Genetic regulation is something still not completely understood. Some people are even suggesting that randomness and selection could even play a role in genetic regulations. All books exist on the subject, and I won't pretend to be a specialist. But do not over simplify bacteria. There is still a lot to discover about my little pets.

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Postby MrMistery » Thu Jun 16, 2005 6:52 pm

I need to read a microbiology book. With the money from my next award, whatever it is, I will buy one. Thanks a milion for opening my mind patrick. I won't pretend to understand but at least I know now how complex the issue is.
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