Before I started this topic, I looked up the words Life, virus and The characteristics of life.

NOTE: if you come across terms you don't understand, plz scroll down. I have included a term-list there.

The definition of life is too long to post here, check it out on the link. Why is this definition so long? It's easy: exceptions. Our planet houses such a biodiversity that everytime they make an all-included definition, a (new) species pops up from which we're sure it's an animal, but misses one key in the chain that makes it life. In order to make a correct definition it expands everytime, again and again.

As qwijibow put it:



quite an understatement

Let's look at what a virus is as an object.



That's what science has been debating about for a long time now. I won't clear it out with one post But I'd like to clarify it to you guys.



These are 2 of the more standard viruses out there. As you see they look a bit like moonlanders (especially the 2nd one). That isn't surprising. Let's look at what a viral infection really is:


(don't look at how crappy the img is, did it in paint )

As you see, the viron (name of one virus molecule) actually 'lands' on this great 'orb' which represents a cell in your body. I'll guide you through the process.

1. This is the evul viron, seeking a good host. No, not a site-hosting company . A host is a living organism in which a parasite (such as a virus) can live, and eat from.
2. The ship has landed. The virus now clamps it's little clawlike tentacles into little tentacles on the outside of your cell to get a good grip for the next phase.
3. In this phase the viron pushes itself through the membrane of the cell with brute force, and injects it's DNA into your cell (a viron can also contain only RNA, but for the sake of simplicity, we'll keep to DNA). Notice that the other viron, the on the right, just uses a sort of needle.
4-5. The DNA reaches the core of the cell and infiltrates it. In this core lies the most important part of the cell: your DNA. The viron's DNA pushes itself between yours and assumes control over the cell. It starts redirecting everything in the cell: it orders the cell to make new virons. Many new virons.
6. After a while, there is no space left for the new virons to go, but they keep coming, so eventually, the cell bursts open, and the young virons are cast out into the cruel world to go find a new host.

Not a nice scene now is it?

Next: the symptoms of life. If a supposed organism shows these signs, it's alive. So they say.

These 7 signs are as follows:
Theme #1 - Cells
From Dictionary.com:

Biology. The smallest structural unit of an organism that is capable of independent functioning, consisting of one or more nuclei, cytoplasm, and various organelles, all surrounded by a semipermeable cell membrane.

Here we come across the first flaw. It says: ...capable of independent functioning... which is not the case with a virus. He has to use a host-cell in order to do things like a normal cell.

Theme#2 - Organization

This means to say that living organisms have a basic structure. Like an energy provider, a command centre, etc.

This is partly true with a viron. They have a nuclei (the core, containing DNA), but nothing else. So there is only a commando centre. So well, they are organised, as one big structure.

Theme#3 - Energy Use

'Living matter acquires matter and energy from the external environment and converts it into different forms.'

ripped from Oceans Online.

Well, this certainly is a DON'T. That exactly why viruses need hostcells, they can't make energy for themselves.

Theme#4 - Homeostasis

'Living matter maintains some type of homeostasis.'

This one is universally accepted. Homeostasis is the property of an open system, especially living organisms, to regulate its internal environment so as to maintain a stable condition. Well, this one we can also cross out on our list. As a matter of fact, a viron has a very minimalistic internal environment.

Theme#5 - Growth

Does a virus grow? Well, if you see a car being built -piece by piece is being put on- and consider that the 'growth' of the car to adulthood, then yes, a viron can grow. But as I see it virons are mainly assembled.

Theme#6 - Reproduction

'Living matter reproduces and passes on genetic material as a blueprint for growth and subsequent reproduction'

Well these babies produce allright. They produce so well we are being killed in the process.

Theme#7 - Evolution

'Living matter evolves.'

Yes, a virus can evolve. Look at the recent 'SARS'. Or influenza, to stay closer at home (influenza = flu, your average home-garden-kitchen virus). SARS originally only affected pigs and animals of the like, until it evolved slightly and could acces humans. And Influenza shows signs that they are becoming more and more resistant to anibiotics, the big medicine that stopped great influenza epidemics. So yes, a virus can certainly evolve.

Lacking 4 of the 7 needed signs, I'd say that it is not really alive. But then again, the most important of these characteristics of life are containing DNA and evolving, in which viruses excellently succeed.

If I had to put it in my own words:
Virons are like zombies are to men. Not with a free will, not with the capability to make food for itself, and needing a host (like a human) to survive, but still with the few vital signs of life.

NOTE: zombies need to eat human flesh in order to 'stay alive'. (Never really figured out why )

Terms:
Viron: A microscopic object consisting out of an outer membrane, an inner membrane and a core with DNA/RNA
Virus: A collective noun for a specific group of virons.
DNA: A long spiralled string of specific proteins that is the blueprint of your body. It describes exactly how you look and what kind of curve your nose has. It is in every cell of your body. If you could take one DNA-string out of a cell and stretch it out, it would be around 2 metres in length (6.6 feet). Surprising, no ?
RNA: Similar to DNA, but not quite the same. It is also a a string of proteins, but one of the main functions of RNA is to copy genetic information from DNA and then translate it into proteins. In virons it is like a copy of DNA that never existed.

URLS:
Physics forum
Wikipedia
And some other site I couldn't remember

Hope this makes maybe somewhat clearer, plenty to debate still!

Qop

 

 

 

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viruses arent alive because they depend on other cells in order to keep themselves alive. if a virus was not able to infect another cell it would just die off.

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Ah ha! But how can something "die off" if it is not "alive?"
I remember kindergarten when we used to talk about what was alive and what was not... or maybe it was on TV, the two kind of blend together. If it moves, eats, and breathes it's alive... But of course there are exceptions... Like some politicians, but that's another topic

 

 

 

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The confusion could go on and one and one and one

I would say a virus is alive, just a much lower form of life.
but then again i would also say a virus is a very very tiny chain letter.

chain letters cannot write themselves, but they do mutate (spelling mistakes)
and spread, and inconvinience a lot of poeple...

Are chain letters alive ???

(maybe life sould be a scale, from a brick (not very alive) up to humans.. (very alive), with virii somwhere in the middle)

what about a snowball rolling down a very very big hill... and every now and again it gets too big, and breaks into 2 rolling snowballs...

Personally, i would define life as a self sustaining chemical reaction.
but that bring the question, are stars alive.

maybe i should have taken philosophy. lol.

EDIT:

and if i was unable to find anything to eat, i would die off
i think thats a question of immortality, not life.

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you just contradicted yourself by saying that viruses aren't alive and then at the end of the sentence talking about them depending on other cells in order to stay alive..
I'm not arguing with you I'm just trying to understand what you're saying

I believe viruses are alive because they can die.
you sort of have to be alive in order to die don't you think?

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Maybe a more appropriate term would be "decay." Buildings don't "die off," they deteriorate. Buildings don't move and infect other buildings though, so that's just a lose analogy

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Viruses are not alive! Their like a person who's become a vegetable because of a car crash. The person is technically dead, but may be kept alive on life support. They rely and recieve energy from their host and they either take over their hosts and terminate it or the host is able to get rid of the virus and form antibodies. secondly, viruses don't posses DNA, meaning they realy don't have a genetic identity.

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A car 'eats' fuel, moves, and needs another life-form to exist (humans). It can 'die', by crashing into a building, or damage.

Still, a ca ris not alive.

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lloydkirk1989, i could argue that you are not alive with similar arguments you gave.

An unborn baby needs life support, yet its not dead is it. its alive, growing.
Virii recieve energy from a host... its alled eating, you recieve energy indirectly from the sun. The earth, and tree's and sun are your life support.

First of all, Virii do have DNA, and who said somthing needs DNA to be alive ?

Did you know your red blood cell's dont have DNA, they dont have a neucleus !
Yet the can live !

Malaria parasites use red blood cells to grow and spead (killing them as they mov on)

People talk of God often.. i dont believe in god myself... BUT.. if god greated everything, then he must have existed before protein existed ?

therfore god has no DNA, nor has he brain cell's blood, or anything else that you have said are essential for life and intelligence.

yet you believe god is alive and intelligent dont you ?

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About the God stuff. The general phrase used is that "He created man in His own image." In other words, he had all that stuff and created us with it. You do bring about a good point though... Where did HE get it? I think this particular subject belongs in a different topic, though, because no one really has room for debate on whether or not a being is alive if it first cannot be proven to exist.

Going back on topic... here's a thought. Computer virus acts in a similar way a real life virus works: Both have "code," whether it be DNA or otherwise, and they replicate by infecting other things (files and cells). Now, which one is more alive than the other? You could say that a computer virus doesn't exist in physical space, but in reality, it is spreading its code on the hardware that is your hard drive. Think about it

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