Question about viruses.

[thoughtudied999]

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?

Thanks

[david23]

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.

[alwaysasking]

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

[victor]

they can’t generate energy? do they produce ATP or else? 😕

[alwaysasking]

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

[Darby]

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…

[MrMistery]

Search the forum. This issue has been discussed and over-discussed

[fscottdahlgren]

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).

[Tae Jun, Yoon]

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

[mehdi71000]

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

[david23]

virus evolved just like basic cells and unicellular organisms etc etc

[mehdi71000]

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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[victor]

wow…that’s an HIV you posted there…
yes, I ever saw a film which said…."viruses are too symetric compared to living things…". I also heard that virus is an another evolution from piece of genetic material (DNA/RNA) when the world is filled with RNA (RNA world)

[ninetails]

yeah if you guys think you are bored and tired of this topic listen to this, if we welcome viral particles to the world of the living, which city do they go to Plant city or the animal city. 😛

Forget it, let them enjoy their special status, come on everyone wants to be different. Don’t they ❓

[victor]

I think that they’ll make a whole brand new city there 😆

[lara]

fine.letz look at it this way.probably,viruses are a totally diffrerent group of organism that evolved in a different pathway.their lifestyle may represent a higher level of specialization that is viruses are more advanced than any other living form????/

[victor]

hmmm…we have made some categories to consider something whether is a living thing (organism) or a non-living thing.
You can see that virus can be considered as a living one because you see that virus shares the common things with the other life-forms which are genetic material and bio-polymers…only those.
But how about the others? anything that virus doesn’t share with the other living thing, such as self-metabolism, reproduction, differentiation? Even though virus shares the most basic and universal things with other living things, it doesn’t mean that virus is a living thing. It lacks another categories to be considered as a living thing….

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