Virus: A Living Entity?

Tough one. I would consider a virus to be a seed. A seed can sit very long periods of time and be viable, but it is incapable of doing anything on it's own without a particular set of circumstances being in place.

So, while an individual virus wouldn't be considered life, in my mind, it definitely is an inert representation of life................much like a dried seed is nothing without water and soil. The cells of the host become the water and soil for the virus.

Even the professionals don't completely agree.

When I consider if something is life, a number qualities are associated. If something lacks only one quality, I might still be able to consider it life. If something lacks most of the qualities, it may be some discrete part of something that is alive (but not alive by itself) or it may not be life at all.

Here are some of the defining qualities:

Is it typically produced by one or more similar things?

Is regular respiration detectable?

Are there patterns of behaviors, functions or processes that that strongly promote the ability to continue exhibiting qualities that suggest it might be alive?

Additionally if it is something people have known about for while, attempting to figure out which to which Kingdom it belongs will provide some historical perspective.

Viruses are produced by other organisms not by other viruses.

Viruses do not respire.

Viruses do not exhibit self preservation on an individual basis.

Additionally viruses aren't part of any Kingdom of life.

I don't consider viruses to be a form of life. They are no more alive than a gesture or a word.

As far as I remember my biology class lessons, Viruses are living things, they learn and adapt. They have a dna//rna depending on their type. They go into a deep sleep or hibernation when out of the host. They dont die, a hardened shell forms as an encapsulation, which breaks open and the virus revives.

They are living things. Non-Living things dont have intelligence, they do-not adapt, they do not re-produce at a large scale... My Vote is out for the "Viruses are living beings".

regards,

Vishal...

Living beings may be a bit of a stretch, but I agree that they are a life form.

If scientists agree that these are alive, I would think that a virus would also be considered to be alive/life.

Furthermore, if scientists believe that viruses can be killed, then by definition, they have to consider them to be alive.

They can't claim that that aren't alive, and also claim that they can kill them. It makes no sense.

They are not defined as life anymore than strands of DNA or RNA are called life.

The capsule of a virus simply contains the RNA or DNA segments inside. The capsule is nothing more than various proteins that form a complex shell to hold the RNA/DNA.

When a virus invades a cell it uses external proteins at one end of the capsule to bind to protein receptors at the host cell's cell wall. They fit together like a lock and key. The lock and key is one method that is used to foil HIV in humans with drugs that either denature the virus protein engagement or jam the receptor site.

When the lock-key is engaged it activates another set of proteins that either drill through the cell membrane walls or use a specific pathway built into the cell wall to inject the virus RNA/DNA inside the host cell.

The RNA/DNA will be carried to the cell nucleus wall by specialized organelles inside the host cell where they are replicated by ribosomes on the nucleus wall.

The host cell's organelles do all the work and a virus is not able to replicate with out the host cell to do its work. Therefore, a virus is not defined as "life".

Viruses can be "killed" by a process called denaturing (unfolding the protein and breaking its hydrogen bonds) or lysing (cutting up) the RNA/DNA or protein chains so that they become inactive or no longer perform their intended function.

The "killing" really is simply rendering the protein system inactive by breaking the functionality of the capsule system and/or lysing the internal RNA/DNA strands.

Oh goody..................is this another argument unfolding?

Intelligent design anyone?.............................just kidding.

Maybe a virus doesn't fit the standard definition of life. But they exist nonetheless, and as far as anyone can tell, their sole purpose for existing is to reproduce............though not by conventional means.

Every species on earth requires something outside of themselves to reproduce. Why should the poor little virus deserve to be called non-life?

Maybe it's time to expand our definition of life.

It wasn't very long ago that these would have been considered absolutely impossible, and yet not only are they here, but they are quite alive.

I really was kidding..................I'm all argued out at the moment. We're just splitting hairs anyway. I can already tell that consensus isn't going to be reached on CR4.

You wrote, "But they exist nonetheless, and as far as anyone can tell, their sole purpose for existing is to reproduce"

Many things exist. Thought exists and is that self replicating?

Again, in order to answer the question their needs to be a standard definition or a yardstick to measure by. This yardstick already exists and by that yardstick the answer to the original question is "no."

Arguing about the validity of that yardstick is another topic altogether and you could probably take it up with the academics that are the keepers of that yardstick. I was just a lowly biology major that has turned electrical engineer-VP.

I accept that definition because:

1. It provides a needed foundation to build a class of learnings on and develop classifications for biological studies.
2. It's current definition is not lacking nor creates a problem with extending our knowledge-base and understanding of biology into the future.
3. Any change to the current definition does not improve or substantially change the subject and study of biology, so there is no compelling reason for scientists, educators, or engineers to tamper with it.

On the flip side, such an argument might be a good excuse to get up and get a beer as an aid to further contemplate the subject, but it is much, much too early in the day to start down that path. ;-)

Yeah, it's too early for beer, and attempting to google my way to a definitive answer from the experts is just giving me a headache. I'll check back in later.

Here's some reading, for anyone that wants to join me in getting a headache.

http://serc.carleton.edu/microbelife/yellowstone/viruslive.html

The definition for life is self-replication.

Viruses require a host cell, so it technically doesn't fall into the category of life, even though it contains proteins, RNA, and in some cases DNA.

The same thing applies to prions, which are proteins, but are unable to self-replicate. Prions are much more insidious than a virus.

Viruses require a host cell's organelles, specifically the ribosomes to copy the RNA (and in some cases DNA) contained in the virus capsule.

The host cell becomes a hatchery and assembles new virus capsules with the RNA/DNA inside. At some point the cell goes into a process called lysis (bursting) and releases copies of the virus into the interstitial fluid outside of the cell and eventually into the bloodstream, etc.

Viruses are an amazing structure and the protein bonding and folding involved is stunning to study, but they are not a life-form as defined by the self-replication clause of life. So, your student is technically correct.

We require lot of food sources to maintain our nourishment which are dissimilar to the food requirements of trees for instance. Our mode of reproduction is different from an amoeba. So is it right to claim the amoeba just breaks into itself and does not reproduce and is not a living entity.

If something can react, learn, adapt and propagate (no matter how) I think it can be claimed to be a living thing.

vishal...

That is not the "accepted" definition of life.

Amoebas reproduce by mitosis, which is the same basic process any cell undergoes. Amoebas still need to replicate their internal DNA and create two nucleuses just like any cell in your body.

You may want to argue what you "feel" constitutes "life", but in the end there needs to exist a standard definition for life and that definition is "self-replication". A virus can not do that by itself.

Correct, self replication is one of several attributes required. Metabolism is another requirement among others.

Many living things need hosts to replicate, I guess now they really aren't living?

Examples?

As I stated earlier, I believe that if a multi-cell creature needs a host, then look at the individual cells in that creature. If those individual cells meet the requirements for life, then the multi-cell creature must also meet those requirements by inheritance of properties.

You've been given examples already and ignored them. Why should anyone offer more?

You charge that I am ignoring previous examples, but you are also ignoring my previous posts that specifically addressed that case.

I see no reason to repeat this information ad nauseum if it is just ignored.

So what you are saying is that a truck carrying vegetables/plant is alive as the vegetables/plants inside the truck are alive..

That a school building is alive as the students and staff inside the building are alive...

Is that exactly what you are implying ... aka by the property of inheritance...

vishal...

You are taking that too far. A building is not alive because it is occupied by people.

However, let's deconstruct what you said. By your definition the reverse would be true, that a multi-cell organism that requires a host to reproduce would imply that the individual cells that make it up must be dead because the greater collection of those cells can not reproduce without a host.

My point was that if the individual cells of an organism are able to satisfy the definition of life, then the organism itself can be classified as life, too.

Your saying a virus can't be alive because it needs a host to replicate. I can think of numerous other living things that can't replicate with out a host. Their are numerous examples in the protozoa, plant, animal, fungal, etc. familes.

If self-replication is one of the requirements for life, then it could be argued with some merit that I'm not a life form since I require a multi-celled host, in my case a female since I'm a man, to replicate. And the replication draws upon material from the host through the umbilical cord for its growth and existence. It may contain the blueprint for full development within its seed, but so does a crystal which depends upon external materials and environmental factors for its growth. So it seems that replication through a host could be considered a factor in defining what constitutes a life form.

You missed the definition, I think, but I am not sure much of me is replicating today, either. Whole family is sick. ;-)

You probably picked up a virus.

Yeah, it comes from the kid - the petri dish for all forms of germs (living and dead). ;-)

The argument goes both ways on whether a virus is living. It has some of the properties that defines life but not all. That can also be said about some bacteria.

You Masters student was expressing the opinion of their educator's or their own conclusions.

If we can agree that a virus is organic at one time it was alive in a host. Why can we not say it living.

You wrote, "If we can agree that a virus is organic..."

Many things are organic and there are many organic compounds in the universe. None are considered life (by themselves).

Organic simply means it either is mater that is derived from a living plant or animal or a compound that contains carbon as part of its molecular structure (i.e., organic chemistry).

By your definition C3H6O would be a living compound. However, you would not consider the acetone in nail polish to be living.

Your definition of self replicating is not the only criteria that they base life on. By this criteria sperm is not alive. What we going to call the egg the host.

Don't see any DNA in Acetone.

It's not my definition. From the Medical Dictionary:

1. The property or quality that distinguishes living organisms from dead organisms and inanimate matter, manifested in functions such as metabolism, growth, reproduction, and response to stimuli or adaptation to the environment originating from within the organism.
2. The characteristic state or condition of a living organism.
3. Living organisms considered as a group.
4. A living being, especially a person.

#1 is the definition that is important here.

My previous point was that "organic" by itself does not denote life. The organism must satisfy other traits to qualify. One of those is self replication, but you are correct that is not the only one.

In the instance of the original post if a virus is "alive" - self replication is the one attribute that a virus can not satisfy and so fails the definition above. Metabolism is another trait that viruses lack.

Someone mentioned a parasite that could not replicate without a host as an example that also fails the definition. I would challenge that. The parasite is a complex creature that is made of specialized organisms that each would satisfy the definition for life and self replication. The parasite is "life" by "inheritance". That is, the properties contained in the individual cells of the parasite endow the parasite with the definition of life.

As I said the argument goes both ways.

You used kill as a metaphor to turn off an engine. In the same aspect we say we kill viruses. Every company out there that produces a disinfectant the label says it kills.

The main definition of kill is to cause death to a living organism. Isn't that what the manufactures of these product are trying to imply in their use if the word kill.

You wrote, "The main definition of kill is to cause death to a living organism."

Like an internet kill switch? Or the kill switch on a tractor, or pain killers, or killing time, or killing legislation, or kill the lights, or kill a rumor, or ...?

How can you back up your statement that states the main definition of kill applies to biological entities?

I think the definition of kill is so permeated in our language as to mean to stop something and that doesn't limit it to the biological.

Regardless, just because you can kill something does not grant it biological life status.

LoL, You just killed His argument...or perhaps it was an execution?

The origins of the word. Though we use the word kill as you have stated are we really killing anything. People have adapted the use of the word kill as a metaphor for ending a lot of things. When I a noisy environment how many time have you seen someone while telling someone to turn something off drag their finger across there throat.

Okay. How does that prove a virus is a living entity?

Your premiss is that because some agent states that it kill bugs or germs implies that they must be alive, but the argument is much too loose because I have already shown that kill is used in a wide variety of ways beyond biological.

To prove something is alive requires more than a simple test whether an agent can extinguish something.

Case in point is halogen can kill a fire. Because we can kill a fire does not imply that fire is alive - at least I find that test too simple and full of flaws.

It in it self doesn't prove anythings alive.

When a manufacture states that their agent what ever the agent is kills bugs or germs . In content are they not implying that it brings death to the bugs or germs? So in the same content a disinfectant says it kills germs and virus. If agent caused death then they must have had life what ever it may be. If life then living.

Your use of kill as a metaphor in terminating something is admirable. Lets see we have killed an engine, a switch, pain, time, legislation, lights, rumor, supposedly my argument and now a fire. Now you want to change word play to extinguish.

Rarely would a fire extinguisher company use the word kill to describe what their product would do to a fire. Nor a insecticide label say it extinguished bugs.

If we use words to define if a virus is living then lets start with Virions which is the infectious form of a virus outside its host.

Simply tell me your definition of life.

Just as we expand our knowledge in many fields and recognize the changes in what that knowledge gives us. Many will differ in view on it as we have.

"An organism is the unit element of a continuous lineage with an individual evolutionary history."

SE Luria, JE Darnell, D Baltimore and A Campbell (1978) General Virology(1978)

Well, Anon, the Medical Dictionary definition does not specifically say that a living organism must be 'self replicating' - it mentions "reproduction" and this is certainly something that viruses do, although they need a host to do it.

Think about what distinguishes a virus from simple strands or bits of DNA - in nature or in the lab. Those bits of DNA do not have any drive nor mechanism to reproduce nor to disperse into an environment (or organism) in which they can reproduce. They have tried and tried to create 'life' in a lab - so far no dice. Non-living bits of DNA do not have the capacity to adapt or evolve or reproduce or take on those characteristics defined as life - there's no question that viruses have these 'life' qualities. If you check out some of the amazing virology sites on the net, you'll see what a bunch of family trees are out there, for the viruses. These characteristics overwhelmingly distinguish a virus from a stray piece of DNA, as a living organism.

The dogma that viruses are not living by definition is an old one, and I think, obsolete.

Read #1 again. The exact operative word used is reproducing, which is the same as self-replicating.

Viruses reproduce. They replicate themselves. They pass on their genome. They mutate and/or adapt to stressors in the environment, and evolve.

Stray bits of DNA don't do any of these 'life like' things.

My opinion in this is based on all the available facts of the day, on which I do not believe the old dogma definition that viruses are not alive. In my opinion viruses meet the criteria stated in your 'medical dictionary' definition, as well as any other living thing.

It would be tough to argue that these are not alive. Isn't DNA the building block of all living things?

http://phagesdb.org/glossary/

Not to mention the fact that they have cute little tails. Cuteness, it seems, is a universal defining feature of life...

Bacteriophages are likely the most abundant biological entities on the planet, with a global population estimated at 10³¹

^{http://www.pnas.org/content/106/11/4160.full}

Kram, Kram, Kram,

You've been a member of CR4 for three and a half years and you still think that its hard to argue anything. All you have to do is ignore the other side and repeat incessantly your own set of opinions. Ignoring everything from the other side is a bit rude but we've seen it happen.

Getting to my point here, as your Scientific American article points out, even in the scientific community there's ambivalence as to if a virus should be on one side or the other of the living or non-living line. This is why I prefer to say its a pointless, useless, misleading description to say a virus is or is not alive. I say this mainly because regardless of either side of the line one stands one can easily make false assumptions about what a virus can or cannot do.

Wow, it's been 3-1/2 years already? Time flies.

I'm not trying to argue that viruses are alive. It's just an interesting subject. The link in # post 41 seems to indicate that even scientists are rethinking their position on these little critters.

Like I've said. I'm still good with yes/no. The reason I'm posting what I find at this point, is that I think that AH's assertion that they are absolutely not alive is inaccurate.

If there is no life process associated with viruses, then scientists are using very sloppy and misleading language when they publish papers that describe ways to kill them...................................and I don't want to hear the kill-switch comparison. It doesn't fit.

It all depends on what your definition of "alive" is.

If you want to make it anything with DNA, then you would have to include phage as living organism.

I think your definition is too wide. We can easily synthesize RNA and DNA in the lab to any specification you want. That would constitute creating life in the lab.

This company takes a little longer than Lens Crafters takes, but they claim to make any sequence you want.

Anon, when you find someone who can synthesize DNA or RNA that actually has the key features of life: reproducing, adapting, evolving etcetera, - be sure to let us know.

DNA is easy to replicate in the lab. DNA is not self replicating, nor self changing. It simply is a chain of amino acids and hydrogen bonds (Adenine, Thymine, Guanine, & Cytosine) bonded together in a specific sequence.

The link I provided will make whatever sequence you like. Just give them the code and limber up your credit card and go.

Anon, you know very well, these labs cannot synthesize an infective virus. They may be able to synthesize a replica of a 'dead' one, which does not do any of the things that are on the list in the definition of 'life'.

In fact the present day proof that viruses should be classified as living things, is exactly in those labs. If viruses were non-living, then a purely synthetic replica would be infective and would behave as naturally occurring viruses do, entering host cells and reproducing, adapting, mutating, etcetera. This is not the case. Ergo, viruses are living things, since the synthetic replica is just a dead one.

You wrote, "Anon, you know very well, these labs cannot synthesize an infective virus."

I did not say that they did or could make a virus. I said that it is easy for a lab to make DNA. DNA (or more often RNA) is the package inside what is called a capsid. The capsid is a "vessel" that is constructed of proteins and bound together to form a rough sphere. Actually, it is more like an icosahedron. Inside that capsid is the RNA and other proteins and enzymes. Some viruses contain DNA instead of RNA.

Here is a schematic of a virus, which is much, much more than just DNA or RNA:

However, I probably should start with a little introduction of DNA (deoxyribonucleic acid) and RNA (Ribonucleic acid). DNA is a double helix strand of amino acids that are composed of four components and arranged in a spiraling staircase like this:

Basically, it is a software program that instructs the cell organelles what proteins to synthesize inside the cell by a process called transcription. DNA is highly packed and held into shape by hydrogen bonds. In the human eukaryote cell nucleus a single DNA strand can be up to 6 feet long if unfolded! Now that is efficient packing!

RNA is like DNA, but instead of a bonded pair it is a single strand of material.

The capsid of a virus contains segments of RNA or in some viruses, DNA. There are other chemicals such a reverse transcriptase enzymes which are used to help the virus insert their RNA strands into the DNA of the host cell. Essentially, the enzymes cleve the host's DNA at a specific point in the chain and then insert the virus's RNA at that point.

When a cell transcribes its own DNA a series of remarkable processes copies the DNA inside the into a single strand of RNA called mRNA (messenger RNA). It is this strand that is the blueprint for making a specific protein needed by the cell. The nucleus wall contains an organelle called a ribosome that is fed one end of the mRNA strand where it then ratchets each segment of the mRNA one at a time and builds a protein as described by the mRNA.

A cell that is hijacked by a virus will not only produce its own needed proteins, but proteins specific to the virus. Essentially, the host cell builds a replica virus (many, actually) out of the raw material inside the host cell and assembles capsids and copies of the virus RNA inside the capsid.

At some point the host cell is loaded with these new replicated viruses and a message is sent to the nucleus of the host cell to auto-selfdestruct (apoptosis). The host cell walls burst and the replicated viruses spew forward into the fluids that surround the dead host cell to infect other cells in the organism. The process repeats until either the host organism dies or its immune system destroys the viruses.

I am sorry for being long winded, but I felt that a clearer understanding of the biology of a virus was in order so that you (and perhaps others) could understand a little better how it all works. There is a lot more than what I have outlined and the whole field of study is amazingly complex (and fascinating). However, this is some of the basics.

As for your argument "Ergo" proof, I hope you can see, first, we can not (to the best of my knowledge) synthesize a complete virus in the lab. Second, if we could it would be just as viable as a real virus because a virus is nothing more than an ordered set of chemicals.

By ordered set of chemicals I mean that a virus is a collection of enzymes, proteins, and other organic chemicals arranges in a specific structure assembled together by hydrogen bonds. The structure may be very complex, but as we are learning, it is something that we can understand as we peel back the layers of the onion (so to speak).

Whether a virus is alive or not purely depends on one's definition of life, not what we can or can not yet do in the lab.

Viruses lack the ability to make copies of themselves without a living host to do the heavy lifting. Viruses do not metabolize or make their own energy like a living cell. Both of these attributes are key (I would postulate) to determining if something is alive. Viruses do neither and there is no energy intake nor waste output from a virus. They are completely inactive until activated by a host cell, which initiates a set of complex protein unfolding when a virus contacts the right spot on a host's cell wall.

Lets make sure I'm following correctly..................

So the capsid is much like the outer shell of a seed, (which you say is alive). Much like a seed, contained within the capsid is the genetic material that undergoes a chemical change that insures the continuation of that particular line of virus, when coming into contact with a suitable host cell.

It sounds a lot like a survival mechanism. Although things that were never alive, could not be programmed to survive........................since survival, continuation of the species, and replication, (even through a host), would be considered traits of a living entity.

I see the virus as a mechanical construct made of proteins that contains fragments of RNA and DNA (among other proteins and enzymes). In other words, a capsid is simply a shell made of proteins much like a cell wall is made of lipids.

The virus shell will simply mechanically change when in contact with another specific protein. The process is simply a form of chemistry where hydrogen bonds are made and broken to change the shape of proteins. It is called protein folding and it is one of the fundamental functions of life.

Proteins and protein folding are not life, but simply structural changes in a collection of organic molecules that determine the protein's shape and thus its function.

The cell walls of your body's cells move material into and out of the cell this way and so do the operation of the organelles.

I think it is wrong to label the activities of protein folding as survival mechanisms. They are too fundamental and we generally look at the systematic function of the whole cell to describe survival or evolution because there are many, many other factors beyond protein folding that are responsible for survival and evolution of a cell.

DNA is not alive........................therefore nothing is alive. Just a collection of mechanical constructs and chemical reactions.

We should have stopped here. Everything would be much simpler.

If it don't fit...............it don't exist.

http://en.wikipedia.org/wiki/Linnaean_taxonomy

In his Imperium Naturae, Linnaeus established three kingdoms, namely Regnum Animale, Regnum Vegetabile and Regnum Lapideum. This approach, the Animal, Vegetable and Mineral Kingdoms, survives today in the popular mind, notably in the form of the parlour game question: "Is it animal, vegetable or mineral?".

I will stop, too.

Did you read the paper?

Mainstream science is slowly reaching the conclusion that viruses resemble "life" more so than "non-life", albeit not in the traditional sense of what is considered to be life.

I'm still content with yes and/or no. Based on my limited amount of knowledge, if someone that knew nothing at all, was to ask me the question, I wouldn't feel comfortable explaining it any other way. Stick to your guns if you want to.

Further conversation will be redundant.

Oh.................one more thing.

Please tell these people to either stop doing the impossible, or change the language in their process.

Thanks

http://childrenshospitalblog.org/live-virus-vaccine-vs-killed-virus-vaccine-whats-the-difference/

From the paper, "Our findings unroot the universal tree of life, and, for the first time, provide evidence for an evolutionary origin of viruses."

That paper supports the idea that viruses evolve. That does not answer the question of whether they are defined as life in of themselves...

Unless, the only attribute that assigns life to any matter is that is simply must evolve to be classified as life.

Is that your definition for life?

For that matter, make this argument easy for all of us. Simply provide what you believe is the definition of life so that we are clear.

From the paper:

Viruses are relatively simple living entities and in many cases maintain a regular structure.

Based on your argument, this statement is grossly inaccurate, and never should have been allowed to stand in a peer reviewed, published, accepted paper.

Somebody is off base here......................is it you, or the guy that published the paper, which was accepted in Feb of 2008 by the International Society for Computational Biology?

Simple question.

If it's not you, then the premise of this paper, and this line in particular, has been turned on it's head, and must be withdrawn.

Yet another inconvenient and published paper:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2837877/

Sorry AH, but the more poking around I do, the weaker your argument becomes.

There's a remote possibility that some things have changed since you were in college.

Nice paper, Science moves on.

Thanks.

Nice work!

The author seems to boil the definition down to possession of a capsid and an organelle such as a replicon.

Essentially, he is trying to reach a redefinition for the term life. Nothing wrong with this, but when we can get a definition that most can agree on we can answer the question with a more positive result.

For now we have seen a number of definitions posed here, some with a systematic set of attributes and some that are a bit more (if not a lot more) ad-hoc. The answer depends on which definition you apply.

It seems to me as though scientists are having to slightly redifine what "life" is, in order to further their understanding of viruses..................................or, the further they understand viruses, the more they feel the need to redefine what "life" is.

Either way, at this point, there doesn't seem to be a right or wrong......................it's simply a definition that may be in transition.

Science is cool like that.

The vaccine example makes it pretty obvious that viruses are widely considered to be living. Here's a quote from the FDA:

"Live-attenuated viral vaccines are manufactured by purifying whole virus from infected cells. Because the virus has been attenuated, or weakened, and no longer is able to cause disease, the purified live virus is used as the vaccine."

If it's good enough for the FDA, I reckon it's good enough for me.

There you go. Scientific proof.

And just think. The great biological debate could have been solved by just contacting the FDA.

For that matter, I bet the EPA could settle the Climate Debate, too? Al Gore should have known that, too!

Okay, Comedy Mode off. ;-)

'....The vaccine example makes it pretty obvious that viruses are widely considered to be living. Here's a quote from the FDA:

"Live-attenuated viral vaccines are manufactured....'

...

REALLY?

...

With that standard of proof all kinds of (non-living) things would gain status as living entities:

Electrical Live Wires

Live TV Broadcasts

Live music recordings or Live music performances.

Concerning defining attributes of something: arguing for the inclusion of any attributes merely on the basis that the same combination of letters can also have that meaning, if a logical fallacy, as it begs the question.

We're talking about alive vs not alive, specifically in the context of viruses, and the scientific definition of what constitutes life.

We've already done this skit.

You're late to the party.

Well, then by self replicating, Humans are not alive, by ur definitions,. Cause we do not "self replicate".

Or now u will provide a new definition for self replication, saying that the organism need not exactly self-replicate...

Definitions are not like "the only way". They are but a guideline based on one's experience and understanding or a groups understanding, experience and approval.

They could not have defined something they did not know existed. That does not mean that it does not exist.

Viruses learn, they adapt, they evolve. And they do replicate or reproduce.. And dont get too literal on the "Kill" issue.

regards,

Vishal..

GA. It is an interesting and obsolete line in the sand. Carl Zimmer has written some interesting books on Parasites and another on viruses called; "Parasite Rex" and a "Planet of Viruses". It was not until I read his short stories on viruses that I changed my view on the role of a virus and had to redefine my view of a parasite. This is a small excerpt from "A Planet of Viruses":

"Many scientists now argue that viruses contain a genetic archive that's been circulating the world for billions of years. When they work try to trace the common ancestry of virus genes, their often work their way back to a time before the first true cells existed.....Patrick Forterre, a French virologist, has even proposed that in the RNA world,viruses invented the double strand DNA molecule to protect their genes from attack. Eventually, the host took over the DNA, which then took over the world. Life as we know it, may have needed viruses to get started."

My vote would go to a living organism. They are drivers of evolution and the inventors of genes. We have evolved from the parasitic take over of viruses.

The entire subject is far more interesting than I ever would have thought. Once again, CR4 has served as a springboard to pique my interest in a subject that never would have occurred to me to look into.

Looks like good reading.

This is an interesting argument, but I'm afraid I'll have to agree, viruses are not living things....They exhibit no signs of life, they don't breath, they don't eat, they don't drink, they don't seek to control their own destiny, they merely reproduce as chance permits...Like fire, fire reproduces itself by chance, but it does not live....It does not seek to replicate by free will....

Depending on the definition one chooses for "life" and the semantics of that definition a virus can be considered either alive or dead. There is no single correct answer for a virus being alive or dead. Somebody here proposed that the definition of "life" is self replication. Under this definition a virus is clearly not a life for it must replicate itself only inside a host cell. A yeast cell, an amoeba and a whole collection of microbes neatly fit in this definition of life for they can replicate without the aid of a host.

However under this definition I am dead, too. I cannot replicate by myself no matter how hard I try. I know that I can be very boring at times but I don't believe that I am dead. So this leads one to question first if the definition for "life" is correct or if the definition is just abbreviated to fit an argument. The definition of life offered does aptly fit for one set of microbes, so it seems that this is an abbreviated definition for the sake of an argument. What is that argument?

To coin a phrase, there in lies the rub. Depending on where one wants a virus to reside in the life, non-life question one can choose a different definition for life. This is precisely the paradox of a virus because the cycle of virus existence goes through dormant times that most closely resemble being dead and active times that closely resemble being alive. Complicating this choice of alive or dead is that most dormant viruses can be altered (sometimes with great difficulty) so that they can never have an active phase again. One cannot readily discriminate an altered dormant virus from an unaltered dormant virus until one prompts it to become an active virus. Philosophically, how can something that appears to be dead, be killed unless it was actually alive while appearing to be dead.

So, are viruses living or dead? I have two answers for this question and only one is probably what readers expect.

Yes! Viruses are living or dead. (There's the obvious answer.)

Living or dead is an invalid question for a virus. This criteria does not apply to a virus.

Some very interesting discussion by all. The biologist in my class said that although viruses contain DNA, that alone does not technically constitute life. I didn't want to start into an arguement in class so I just told him that was a good point but that I would have to check with my priest on his point. Thanks everyone.

Not that it matters, but I'm just fine with the explanation given in the link in #16.

Yes and/or no. It works for me.

I agree. Yes/no is an acceptable answer. I do prefer though that this maybe an inappropriate question for a virus. The question of life for a virus is kind of like quantum mechanics for Biology. Its like asking how an electron can tunnel from location "A" to location "D" without ever traveling across locations "B" & "C". It doesn't make Newtonian sense that any object can do this but it does happen. Well it doesn't make any sense that you cannot say if anything is alive or not but neither maybe the correct answer.

Yeah. We could drive ourselves crazy with this.

No one would try to argue that a radish seed is alive..................it's just viable or not. But sure enough, when it comes into contact with a "host"..............which would be moist soil with some light shining on it, the preprogrammed, chemical reaction takes place that insures the survival of the species, and it creates a plant...............which everyone would say is alive. I don't think the seed ever was. Nor will the seeds that the plant produces be alive.

A virus doesn't resemble life until it latches onto the host cell and goes through the chemical process that insures it's survival. A short lived, parasitic relationship, in which the host cell is forced to become the reproductive organ of the virus. Outside of that moment, the virus is no more alive than the radish seed. Only viable or not.

I think the seed is simply a dormant plant cell (it is still alive) and not a viable example.

These seeds sure were alive for a long time. What kept them alive? What nourished them to keep them alive? From Wiki:

• The oldest carbon-14-dated seed that has grown into a viable plant was a Judean date palm seed about 2,000 years old, recovered from excavations at Herod the Great's palace on Masada in Israel. It was germinated in 2005.^[1][2][3][4] (For more details refer to Judean date palm: Germination of 2000 year-old seed).
• The second oldest viable seed recorded is the carbon-14-dated 1,300-year-old sacred lotus (Nelumbo nucifera), recovered from a dry lakebed in northeastern China in 1995

I swear I found this after I posted the seed analogy. Do you disagree with this?

http://www.scientificamerican.com/article.cfm?id=are-viruses-alive-2004&page=2

they verge on life.

Nice reduction.

It's funny how he won't quite go one way or the other...............on the verge of a distinction.

I'm still good with yes and no.

Because the nut of the article is that viruses play a role in the development of life. Nor argument here about that.

For your case here I think you should point out to a similarly high minded biologist in a future terrorism class that a non-living toxin will be a limited quantity to be identified and contained. Since viral and bacterial agents can make more of themselves inside or outside of a host the easy to remember designation of living is more appropriate to both agents regardless of the truth of whether a virus is actually living.

I don't think viruses 'can make more of themselves inside or outside a host'.

I'm fairly certain that viruses are not produced 'outside' a host. Additionally,

the production inside a host is done by the host, so 'make more of themselves' isn't accurate.

Tattoos are not alive, right? Yet, the effect of some people being exposed to the sight of tattoos on other people can cause new tattoos to be produced on those effected. Still the population of tattoos cannot be usefully described as 'making more of themselves'.

Observing the discussion, I wonder:

Is a virus the semiconductor of biology?

Is it a conductor or not? versus Is it alive or not?

Answer: Sometimes.

The human race is a virus on this earth (multiply and destroy).....we are alive.

"Viruses, however, parasitize essentially all biomolecular aspects of life. That is, they depend on the host cell for the raw materials and energy necessary for nucleic acid synthesis, protein synthesis, processing and transport, and all other biochemical activities that allow the virus to multiply and spread."

Yep!.....that sounds like us.....the host being the earth. Problem is, we dont have another host to go to, once this one is spent. Bugger!

Gentlemen I must share this, as this was the essay question in a college microbiology final years ago. I had similar views to most of your personal interpolations, and believed a virus to be a living thing. I wrote for three pages on the subject, in much the same vein, and felt awfully proud of my efforts. I recieved a single large red x through each page from my professor, with a terse note directing me to a single paragraph in the text...which I will not repeat here. Suffice it to say that your friend with the Masters is absolutely correct scientifically.

And I still believe I'm correct philosophically, but I left that experience a wiser man....with a B not an A.

Light can be considered as both a particle and a wave because it exhibits the properties of both. Both aspects are understood and are treated as equally valid, but they are rarely viewed together. How it is treated depends on what property of light the viewer is studying at the time.

Viruses fall into the same category, it can be considered as both a life form and a non-living chemical structure, because it exhibits the properties of both.

So my answer to the original question is, Yes............and No. I consider either answer to be equally valid, and in no way to be contradictory.

The prion is a step below a virus. It causes BSE or Mad Cow Disease. I would consider anything that reproduces itself to be a living thing in some sense of the word living. I like your answer. Issues need to be looked at from various points of view.