QUOTE (Calantyr @ Jul 27 2006, 10:41 PM)
However here you have the RNA strands simply using external methods to move. Why does it need another method? I suppose it's a bit like parasite in that respect. I would say that it pretty much fulfills most if not all the main criteria for life.
M Movement - It uses external methods to move, it doesn't really need anything else. Can anyone think of other life forms that rely on external methods to move? Maybe a Verruca or something? Or does that dig itself into the flesh?
R Reproduction - It replicates itself.
G Growth - As part of the process of replication, yes.
R Respiration - Hmmm... okay that's a tricky one. Not sure it does that.
I Irritability - It responds to external stimulus, so yes.
N Nutrition - It feeds of healthy cells, so yup.
E Excretion - I think that there is waste material left over once it has replicated itself, so yup.
Movement: nope it don't move
Replication: Ok, I'm gonna go into depth on this because I had some thoughts on this. Let's say I had a photo of someone I liked a lot. I liked it so much I placed it into a photo copier and as if by magic I had produced 100 copies of that person that I could place in a shrine to them. I certainly wouldn't call photos a self replicating thing. The photocopier did that. That's a bit like virus' they are a a set of instructions to make more of themselves. They need a cell to infiltrate to the manafacture additional cells, and it's the cell they infiltrate that does the creation. On their own though, given all the materials nessecary they would do nothing.
Growth: Well growth and replication are too different things. They don't gain any physical size in their life cycle, so they don't grow.
Respire: Don't do that either
Irritability: They don't respond to external stimuli. As in they don't change their actions based on situation. Since they don't move, excrete, fire off electrical activity, grow, run, or even activily seek out cells. They don't really respond. They literally by the luck of sheer overwhelming numbers end up filling all available space, through the above method of infiltrated cells spewing them out on mass.
Nutritions: a tricky one you could argue that it needs cells to replicate more of it self, and that on some level we all need that. But then you could argue that the cell it infiltrates isn't actually killed, it's just reprogramed to another means, and since the virus doesn't actually take anything from the cell it infects. It can't be drawing sustenance. So both ways.. well kinda work. Dunno. Iffy.
Excretion: nope they don't excrete, they enter cell, mass produce virus. The cell normally dies because neighbours of host kill it for being different. Or else because the cell ceases all normal functions and eventually starves to death. That's closer to suicide than viral waste. Otherwise we could say the US excretes out bombed out middle eastern countries. Amusing a phrase as that is. It's not true.
The thing about RNA and DNA is that, generation one of life (the basics of the basics), didn't have either. DNA and RNA came into existence most likely as without them, life can't send even the most simple improvements to it's descendants. Making it quite literally a blueprint rather than it's own entity.
Somewhere along that chain, Virus' came into existence, as RNA sequences that rather than spawning themselves, they kinda got other cells to make more of themselves for them (anyone else think that's so god damned lazy?) They certainly seem in the spirit of what makes life, and have been around for the majority of the time lifes been on earth. They just work on such a basic and fundamental different way because their evolutionary divide from what we consider the main vein of life was so early in life's history. They have differences on how they work, down to even the basic molecular level. Unlike say plants, which divided from us evolutionarily on the grand scheme of the age of the world fairly recently (theories say that the majority of the age of the world, the world never developed beyond the microscopic, large visible plants and animals are actually new features, compared to the age of life on earth.)
I've decided that virus' are alive, just the definitions are way too limited by the fact that we only consider things alive that have inherited a certain set of traits and method of getting things done. Virus' despite being a lot older than even plants, just happened to have divided from the main vein very very early, so wasn't on the band wagen to get nifty and neat features that we got, They did however gain super fast evolution, a side affect of spawning in such massive numbers.
However with it said that fundamental and basic, molecular differences in things not being a reason for things to not be alive, that opens the door to more and more things like the early mentioned computer virus' which are even more fundamentally different from the main vein of life, then normal virus' are.