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The Problem With Viruses


par4dcourse
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Since the swine flu is in the news ad nauseum of late, it started me thinking about something I read in Carl Sagan's "Shadows of Forgotten Ancestors." It's a great book on evolution, and he in one part describes the chemical workings of DNA, and how life may have emerged eons ago as a self-sustaining chemical reaction.

 

He describes a virus as just a snippet of DNA wrapped in protein. It has only one of the common attributes of life: reproduction. It's not mobile except for via second parties and doesn't use energy (eat). What it does do quite well is make host cells reproduce it. Possibly just a self sustaining chemical reaction.

 

Here's the question: Are viruses "alive"?

 

On a slightly less serious note: There is a plethora of single-celled organisms that fit all of the definitions of life, protazoa, amoeba, flagellata, etc.

 

Second question (mainly for xians): how many Petri dishes did noah have on his boat? Some of the non-lethal strains could have ridden in host animals, but there are millions of non parasitic strains. Since gawd did all of his creating back in Genesis 1, we must assume noah had two of each (stupid, since they're asexual). And why did a loving gawd create bugs no one can see to torment and kill his beloved creation?

 

Personally, I think the big guy had some killer ghangha and a fifth of Crown. What else could explain the platypus? silverpenny013Hmmm.gif

 

 

 

 

 

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Par, I think in order to address this question we must first ask the question of questions...

 

What is life?

 

Increasingly I am agreeing with the theoretical biologist Robert Rosen (yes him again). He created a relational model of organisms which he called “metabolic, repair systems”. He further said that organisms are closed to efficient causation.

 

Viruses posses no metabolism of their own. They must hijack the metabolism of honest-to-god organisms in order to replicate.

 

I would say that viruses are manifestations of ecosystems and that they are indicative of living systems, but they themselves are not alive.

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Since the swine flu is in the news ad nauseum of late, it started me thinking about something I read in Carl Sagan's "Shadows of Forgotten Ancestors." It's a great book on evolution, and he in one part describes the chemical workings of DNA, and how life may have emerged eons ago as a self-sustaining chemical reaction.

 

He describes a virus as just a snippet of DNA wrapped in protein. It has only one of the common attributes of life: reproduction. It's not mobile except for via second parties and doesn't use energy (eat). What it does do quite well is make host cells reproduce it. Possibly just a self sustaining chemical reaction.

 

Here's the question: Are viruses "alive"?

 

I have a more "liberal" definition of life than many. I think any ongoing thing that requires organization beyond the basic chemical reactions or other natural phenomena inherent to the universe for its self perpetuation could be considered alive. When we find ongoing chemical reactions on other planets, we will probably use inappropriate earth-centric criteria for determining whether this is life or not.

 

But what do I know? I think computers are alive. And computer viruses.

 

From Wikipedia:

 

Opinions differ on whether viruses are a form of life, or organic structures that interact with living organisms.

 

They don't know either.

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This is a question that plagues microbiologists, and some do classify viruses as being alive because they must reproduce and have DNA or RNA (not both) and can be rendered inactive so that they can not infect a cell.

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Viruses' ability to transfer their genetic information to subsequent generations suggests that they are 'alive' to some extent. In addition they share some (but not all) basic traits of life, they evolve and adapt to new environments and situations. The presence of both RNA and DNA viruses show that somewhere along the evolution of genetic structures viruses were able to adapt to both molecule types. Considering that we are essentially asking if replicating genetic material (regardless of mechanism) is 'alive', this appears to suggest Shyone's definition of life when considering the alive-ness of viruses.

 

It would probably be good to emphasize organization that happens on its own (from natural physical laws, like gravitationally bound systems which we do not consider to be 'alive') to organization that occurs as a result of self-propagation (such as means of genetic transfer to subsequent generations).

 

Regardless of whether we consider them to be alive or not, they are successful at replicating and are numerous all over the planet. One study showed that there is up to 2.5 x 108 bacteriophage viruses per cm3 of seawater.

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That is the classic bio question. I remember having to try to answer that question in 7th grade, only to learn there isn't a correct answer. For me, the it was a good way of showing that nature does not follow our neat organization so we are going to be stuck with some things that defy our categories.

Viruses do reproduce, but they are unable to do so by themselves, ie they don't contain the necessary molecular machinery to split or create other viruses, so they must hijack a cell. Viruses do not have a means of converting chemical energy to mechanical energy. Since they are just proteinaceous packets of genetic material (either DNA or RNA), I have always answered that I don't think they are alive. But perhaps the criteria for being alive will change.

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It's funny that YEC's never give their almighty proper kudos for creating flu viruses, the black plague, salmonella, malaria, etc. when we know he created everything that is. silverpenny013Hmmm.gif

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