Question about viruses.

About microscopic forms of life, including Bacteria, Archea, protozoans, algae and fungi. Topics relating to viruses, viroids and prions also belong here.

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thoughtudied999
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Question about viruses.

Post by thoughtudied999 » Sun May 27, 2007 7:04 pm

Why are viruses not considered living? They contain DNA and reproduce. I have been told that it is because they must have a host cell, but I don't see how that makes them non-living. Can anybody clear this up for me?

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david23
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Post by david23 » Sun May 27, 2007 7:18 pm

It's just a classification. There obviously have to be limits to the definition of a living organism. if you broaden the definition, u might as well include prions, or even a plasmid. It's not really anyone's fault except who ever came up with those definitions like decades ago.

You understand that a virus need a host cell, so I guess there is no need to explain the structure of a virus.

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alwaysasking
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Post by alwaysasking » Mon May 28, 2007 7:54 am

They reproduce only in a host cell and they cannot generate energy if not in a host cell.

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victor
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Post by victor » Mon May 28, 2007 9:59 am

they can't generate energy? do they produce ATP or else? :?
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A: They have all the solutions.

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alwaysasking
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Post by alwaysasking » Mon May 28, 2007 10:04 am

They can't generate their own energy.They use the host's ATP.They also lack ability of synthesizing organic molecules.

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Post by Darby » Mon May 28, 2007 8:57 pm

There are a few other things that they lack:

- they are not truly cellular (even the ones with membranes steal it from the host cells, and many have protein coats rather than membranes).

- they neither grow nor develop - they are produced in their "final" form.

- as mentioned, free viruses have no metabolic processes.

The one about needing a host cell to reproduce seems a bit bogus, as that also applies to a lot of bacteria and protozoan parasites.

Personally, I think that a definition of "living" that excludes viruses is too restrictive, but folks can define it as they wish...

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MrMistery
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Post by MrMistery » Tue May 29, 2007 7:53 am

Search the forum. This issue has been discussed and over-discussed
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fscottdahlgren
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Post by fscottdahlgren » Tue Jun 12, 2007 8:03 am

I define life as a system avoiding equilibrium. A virus sets up no concentration gradients, etc., and therefore is not alive. However, by my definition the atmosphere is alive, which a lot of people here probably wouldn't agree with (including myself).

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Tae Jun, Yoon
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Post by Tae Jun, Yoon » Tue Jun 19, 2007 1:15 pm

Many biologists think Organisms should satisfy this condition
(a) order
(b) evolutionary adaptation
(c) response to the change
(d) regulation
(e) energy processing
(f) growth & development
(g) reproduction
: This classification was quoted in "BIOLOGY - 7th Ed"

Viruses don't satisfy many of this standard. And especially virus can't do energy processing by itself. So biologists classify virus as non-organism
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is that somewhere it hide a well - The Little Prince

mehdi71000
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Post by mehdi71000 » Tue Jun 19, 2007 5:50 pm

Where do they come from :shock:
Are we under modification by them?
Aliens I say

david23
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Post by david23 » Tue Jun 19, 2007 9:53 pm

virus evolved just like basic cells and unicellular organisms etc etc

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Post by mehdi71000 » Tue Jun 19, 2007 11:34 pm

Have you seen them under a electron microscope they are so neat. Its like they are designed by a machine or some thing
Some are like machines like the famous phage virus i saw this picture once the needle looked like a syringe needle. Like a perfect cylinder cut at 45dgrees on th x z plane. Mind boggling.
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