Are Viri (viruses?) Alive?

We have discussed the origin of life a lot. I don't think we've ever had any discussion on just what being "alive" means that came to any kind of conclusion.I will come down on a particular side of this question. I think that viri are alive.My reasons are that they use resources, reproduce and evolve.

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Common sense isn't

I'll come down on the opposite side: like prions, I think they're just short of being alive.My reason is that they require other living things to perform "basic" life functions, and in the absence of those other organisms are unable to use resources, reproduce, or evolve.I don't think they're exactly non-living, either - maybe, proto-life? Sub-life?

I think it's just a definition, and if scientists would choose a definition, then whatever definition they chose would be just fine. Life could mean "anything that reproduces," and virii would be alive. Life could mean "anything that can reproduce without help from other life forms," and they wouldn't be alive.A lawyer would eat me alive for that one, since no human can reproduce without help from another life form (another human), and you can't survive to reproduce without help from bacteria. But if we could ban all lawyers and lawyer thinking, so that I don't have to rewrite the above definition in good, legal terms, I think you can understand what I'm saying.

Ok, read this except from "The Fifth Miracle"
http://www.creationtalk.com/...age-board-forum/viewtopic.phpNow, this virus needed very special chemicals that couldn't reasonably be expected to be available outside the lab. But they were replicating without a cell around to help out. And some forms arose from what we can all agree (I think) are non living chemicals.

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Common sense isn't

In fact, it looks like it needs everything that it uses in the cells. And it doesn't appear to be the entire virus that is replicating, just the RNA payload. No protein coat, nothing but the RNA.I can stick my DNA in a test tube and run a PCR to duplicate it a thousand-fold, but I've hardly "self-replicated."At best, we're on two sides of a very thin line, I think. You say tomato, etc.

Yea, I agree about the thin line. But this "thing" is replicating without a living cell and it is capable of evolving. How is that not alive?

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Common sense isn't

I get the distinct impression that in the nailing down of a definition for life we would be in the same trap we encounter with the definition of transitional.Would it be not more conducive to an investigation of the phenomena of life to simply be able to take what we know about physical chemistry and the interplay of forces at that level and show how they can produce any of the processes that we can consider necessary for life.We understand the way in which ATP,for instance,performs its work[At least in a basic way]or how hemoglobin in the blood transports oxygen to tissues and uptakes carbon dioxide for disposal by the lungs.It is a long haul to being able to explain great details since life is complex but that is not to say that we are not at least defining the borders enough to glimpse a vague outline..With time the shadows gradually give way to the illumination provided by scientific investigation.But the beauty of it that always will stay with me is that for every question we answer we garner many more questions each of which shows an new piece of a puzzle,often which delight us most when they are not what we expect.We know that elements have certain properties on their own. We have two poisons combined which we cannot live without in salt.Water is the comination of two hydrogen atoms and one oxygen atom and look at the amazing properties displayed by it.who can look at the periodic table and guess at what the outcome of combining any of just 2 of them much less 3 or dozens.And then to have them change configuration from one location to another so that they do not repeat themselves over and over like water or salt. Imagine the possibilities such as nerves transmitting electrical impulses as a result of the potential difference between just 2 elements, potassium and sodium.All your thoughts, every beat of your heart, every movement of your body comes down to this.The devil is in the details.

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'Everyone is entitled to his own opinion but not his own facts.'
(Daniel Patrick Moynihan)

I guess I thought I covered that. It's not really replicating, because it's not reproducing the entire thing. Just the RNA.I mean, how is what this RNA is doing different than crystal growth?

I'm actually replying to your earlier comment regarding viruses. I have to side with Ned that they are alive.Your main problem, seems to be that they need other organisms to allow them to do what other organisms do on their own.But I am not sure if that is the right way to look at it. How is that different from an organism needing a specific chemical environment to be able to do what it does?The only difference seems to be that viruses need the nice chemical bath environments that cells generally provide (or else labs, which is what this later post was about).In fact, bacteria end up acting like viruses when not in the correct environment and go dormant until they happen to get placed back into that environment.How then can we really distinguish between the two (as far as "life" is concerned)?

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holmes
"...what a fool believes he sees, no wise man has the power to reason away.."(D. Bros)

Or how about a tapeworm?

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Common sense isn't

Since I study a strange class of virus like elements that pervade the genomes of just about all lifeforms, I thought I would throw in my two cents. I also think that making a clear distinction between life and non-life in the case of viruses is a tricky. From population genetics to evolutionary strategy, there is very little (if anything) to distinguish a virus from any other "living" replicating organsism. They are under the same constraints and are influenced by the same evolutionary parameters as any other parasite. That they require a host cell to live is not such a fixed trait of non-life as we require food (i.e. external factors that we do not produce to live) and their are other non-viral obligate parasites. The viruses evolutionary strategy is to minimize its own content and maximize its usage of the environment i.e. extremely streamlined. Even at that, some viruses such as HIV for example are monsterously complex. There is also some theoretical work suggesting that retrotransposons (related to retroviruses) are the basis of life i.e. they are simple replicators that diversified and produced genes with other functions not virally related. So proto-life, simple-life, streamlined life..whatever, it still seems they meet the criteria.But I agree with sidelined as well, defining life is probably as difficult a concept as defining a species.

It seems to me that something must have a sufficient number of "systems" on-board to be really alive. Viri just don't do enough by themselves.Do viri do the same things as bacteria? Sure. But only in the presence of cells. Prior to that they're inert, lifeless. Bacteria may take on a similar spore form, but that's a specific reaction to a stimulus, not their basic state.I realize that my line may be arbitrary, but the thing is, I think yours is, too. If viri are alive, are prions? And if prions are alive, are crystals? All these things reproduce soley in a specfic chemical environment. Prions are more like crystals than they are like bacteria. And viri are more like prions then they are like bacteria. Therefore I come to the conclusion that viri, like crystals and prions, are not living things. They're the closest you can get to life without actually being alive, maybe.Heh, I think we're all hampered by the fact that nature feels no particular need to divide itself into easily recognized boundaries, but rather, there's an entire continuum of life, and every time you try to draw a line, there's something with a foot on both sides. [This message has been edited by crashfrog, 02-03-2004]

actually a virus is more like a bacteria than a prion. You produce the prion protein, it is not an exogenous agent. In addition, a prion infection does not lead to an increase in the number of prion molecules. The infecting prion causes the host prions to take on the misfolded form. Thus, prions are not replicators but modifiers. Also, prions are exculsively endogenous i.e. produced from a vertically transmitted gene, and the misfolded ones are more like a poison contained in food, than an exogenous infectious agent.A virus contains a genome with enough information to replicate itself in a cell and enough information to get itself back out of the cell when necessary including modifiying and controlling host cell functions to serve that end. These are hardly minimal functions. Saying that they do not have "enough" to qualify as alive to me is too arbitrary. Then only plants are alive because they can photosynthesize and we are absolutely dependent on their photosynthesis to survive.

Nonetheless I see the distinction as arbitrary. A virus can only replicate in a specific chemical environment - the cell. A prion can only replicate in a specific chemical environment - one that includes the nominal protien. A bacterium can replicate in any envrionment in which it can maintain life chemistry."Modifers?" Prions modify protiens into exact copies of themselves. Living things "modify" materials into copies of themselves. Seems like the terms aren't much of a distinction to me.Viruses have no metabolism. Prions have no metabolism. Bacteria have metabolism.Viruses don't respond to changes in their environment. Prions don't respond to changes in their environment. Bacteria respond to changes in their environment.To me, it's like the difference between a combustion engine and a lever. At idle, the engine is still doing something. The lever does nothing until you use it for a task. Even if a bacteria isn't responding to something in the environment, it's still doing something - life processes continue. The virus is inert until specific chemical interactions occur.Viruses seem much more like prions than like bacteria to me. But then, I'm no biologist. Maybe my criteria are irrelevant, but they seem noteworthy to me.I'm comfortable with putting viruses and prions in a "proto-life" category, as I feel that they're more alive than crystals. But they're less alive than bacteria, it seems to me.If I might ask - how would you tell the difference between a "living" virus and a dead one?[This message has been edited by crashfrog, 02-03-2004]

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Or how about a tapeworm?

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No thanks Ned, I'm fine with the omelette.

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The dark nursery of evolution is very dark indeed.
Brad McFall