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Name: Sidd H.
Status: Student
Age: 16
Location: N/A
Country: N/A
Date: N/A 


Question:
I read your question about the smallest organism, and I was wondering if Prions, single protein pathogens, could be counted as organisms since viruses are. This would make them the smallest organism, correct?



Replies:
Scientists still argue over whether viruses ARE organisms. I wouldn't count prions as organisms, but I would say they are the smallest INFECTIOUS AGENTS.

van hoeck


If you would take reproduction as the main criteria for being a living organism, then prions fit that criteria: they reproduce themselves by forcing pre-existing proteins to become like them. Prions are mammalian proteins that are folded in a particular way: In this structural shape they are (1) extremely stable, (2) disabled in their normal action in cellular life and (3) can force normally folded proteins of their kind to fold into this prion type.

However, reproduction in this way is different from classical biological reproduction in that it can only produce 'offspring' from already existing akind. And there is no nucleic acid involved in their life cycle. That is the major distinction with viruses.

I had a discussion with a geologist once who described how chrystals are produced from minerals dissolved in fluids. They form to a regular shape and pattern, and the way chrystals grow is similar to biological growth in some respect. Still, we would not call chrystals living material. I think the growth of prions belong to this same class of materials, although they are produced from organic material.

Whether or not you would include prions as independent living organisms depends on what definition you want to accept. They are certainly infectious, and pathogenic, and their discovery forced us to reevaluate our views on infectious diseases.

Trudy Wassenaar


Nope! Neither prions nore viruses are considered organisms...if one considers an organism a life form.

PF



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