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Hmmm....differences between bacteria/eukaryote ribosomes?

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Hmmm....differences between bacteria/eukaryote ribosomes?

Postby sundew773 » Sun Jun 26, 2005 10:09 pm

Trying to answer a question that asks for differences between bacteria/eukaryote ribosomes?

It specifically asks for differences that are important medically. :shock:
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Postby MrMistery » Mon Jun 27, 2005 8:25 pm

Well i do not know about what differences are important medically but here are the differences:
1. The size of the ribosoms: the ribosom has 80 S in the centrifuge in eucaryotes, and 70 S in procaryotes
2. The subunits: The big subunit has 60 s in eucaryotes and 50S in bacteria
The small subunit has 40 S in eukaryotic cells and 30 S in bacteria
3. The kind of rRNA found:
In eucaryotes the big subunit contains 28 S and 5 S rRNA, and in bacteria it contains 23 S and 5 S
In eucaryotes the small subunit contains 18 S rRNA and in bacteria 16 S rRNA
*Off-topic a little: the 16 S rRNA in the subunit of archea resembles enormassly to the 18 S rRNA in eukaryotes*

Hope this helps
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Postby protozoan » Mon Jun 27, 2005 8:25 pm

I think ribosomes of procaryotic organisms are sensitive to antibiotics while eucaryotic not. This could explain why when you intake antibiotics you are not dead while procaryotic organisms in your body are dead (im not sure about it cause eucaryotic have procaryotic ribosomes in mitochondrias and plastids).
Procaryotic ribosomes have sedimental constant 70S while eucaryotic 80S.
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Postby MrMistery » Mon Jun 27, 2005 8:32 pm

I do not think it is the ribosoms that are sensitive to antibiotics in bacteria.
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Postby EmmVeePee » Mon Jun 27, 2005 8:45 pm

Some antibiotics take advantage of the ribosomal differences in the cells. For example.

Tetracycline - Binds in the A-site of the ribosome in Prokaryotes to stop tRNA binding.
Aminoglycoside - Binds to the 30S unit of the prokaryote ribosome, mishapes it, and stops transcription.
Macrolide - Binds to the 50S unit and stops mRNA movement in the ribosome.

These are usually highly effective/broad spectrum anti-biotics.

But a lot of antibiotics don't take advantage of this.

Pencillins block NAM units of the cell wall from forming, which weakens the structural integrity of the cell.

Polyenes disturb the cytoplasmic membrane by binding to molecules embedded in the cell membrane. This causes large holes to form in th membrane which messes up chemical gradients.

Quinolones and Fluroquinolones bind to DNA Gyrase which is an enzyme unique to bacterial DNA replication. (DNA Polymerase in bacteria cells are too similar to take advantage of)


I gave you a bit more information than you may want, but knowledge is power or something like that.
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Postby MrMistery » Mon Jun 27, 2005 9:05 pm

I will thank you for that, it is really valuable information... So thank you :D
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Postby sundew773 » Tue Jun 28, 2005 2:09 am

Thanks so much, this board is awesome!! I think I can come up with a good answer to the question.

I found out that many medicines will also target only 70S ribosomal units...thus targeting bacteria and not the body's cells (which are larger, at 80S). They will then block translation in the bacteria by binding 70S and "locking it."

:D
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Postby protozoan » Tue Jun 28, 2005 9:03 am

MrMistery wrote

I do not think it is the ribosoms that are sensitive to antibiotics in bacteria


Ribosomes are one of five possible sites which are sensitive to antibiotics in procaryotic cell. As EmmVeePee wrote it is Cell wall, Cytoplasmic membrane, DNA, Ribosomes and Cell metabolism too. It depends only on how antibioticum is used. I needed to say that though it probably is not needed.
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Postby zami'87. » Sat Jul 02, 2005 5:06 pm

Thanks EmmVeePee :D REALLY USEFULL INFORMATIONS!
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