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Virus

wjmelements
Posts: 8,206
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4/22/2010 9:48:08 AM
Posted: 6 years ago
It's hard to classify what is living and what is not for arguing this. The primary reason that viruses aren't considered life involves that they don't collect energy, while other life does. However, we can say that all other life except Prokaryotes have atleast one cell nucleus, so Prokaryotes aren't life. It's only a matter of defintion, and there is no valid criterion for drawing the line.
in the blink of an eye you finally see the light
Volkov
Posts: 9,765
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4/22/2010 9:49:07 AM
Posted: 6 years ago
Viruses are not considered alive. They're sort of inbetween the definition of "life" and "inanimate." They have no metabolic functions and they can only replicate through infecting a biological, living cell. They don't fit the definition of "life" in any normal way.
belle
Posts: 4,113
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4/22/2010 11:39:00 AM
Posted: 6 years ago
At 4/22/2010 9:49:07 AM, Volkov wrote:
Viruses are not considered alive. They're sort of inbetween the definition of "life" and "inanimate." They have no metabolic functions and they can only replicate through infecting a biological, living cell. They don't fit the definition of "life" in any normal way.

this pretty much covers it, although wjm's point about things depending on how you define life is also valid. after all, it can't *just* be the ability to reproduce on your own. no doubt many parasites require other species in order to reproduce properly but it doesn't make them not alive. i think the lack of metabolism of any kind is much more damning.
evidently i only come to ddo to avoid doing homework...
Anarcho
Posts: 887
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4/22/2010 5:01:01 PM
Posted: 6 years ago
At 4/22/2010 11:39:00 AM, belle wrote:
At 4/22/2010 9:49:07 AM, Volkov wrote:
Viruses are not considered alive. They're sort of inbetween the definition of "life" and "inanimate." They have no metabolic functions and they can only replicate through infecting a biological, living cell. They don't fit the definition of "life" in any normal way.

this pretty much covers it, although wjm's point about things depending on how you define life is also valid. after all, it can't *just* be the ability to reproduce on your own. no doubt many parasites require other species in order to reproduce properly but it doesn't make them not alive. i think the lack of metabolism of any kind is much more damning.
Damn you took the words right out of my mouth.
InsertNameHere wrote: "If we evolved from apes then why are apes still around?

This is semi-serious btw. It's something that seems strange to me. You'd think that entire species would cease to exist if other ones evolved from them."

Anarcho wrote: *facepalm*
omelet
Posts: 416
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4/22/2010 5:34:25 PM
Posted: 6 years ago
At 4/22/2010 11:39:00 AM, belle wrote:
after all, it can't *just* be the ability to reproduce on your own. no doubt many parasites require other species in order to reproduce properly but it doesn't make them not alive.
Plus, what about all those people who are infertile and incapable of breeding?
That also causes problems with a consistent application of the primary "species" definition.
cult-logic
Posts: 20
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4/22/2010 7:32:34 PM
Posted: 6 years ago
At 4/22/2010 5:34:25 PM, omelet wrote:
Plus, what about all those people who are infertile and incapable of breeding?
That also causes problems with a consistent application of the primary "species" definition.

It's not a matter of whether or not each individual can reproduce. Being infertile does not make one inanimate.
The basic criteria of life are biological self-sustaining processes. The ability to maintain homeostasis and metabolism, being capable of growth and response to a stimulus, and the ability to reproduce and adapt through generations are the main ones, I believe.

Because there are so many of these requirements, it makes it hard to know where to draw the line with things like viruses, which don't possess all of these characteristics.
Puck
Posts: 6,457
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4/22/2010 8:04:41 PM
Posted: 6 years ago
At 4/22/2010 7:32:34 PM, cult-logic wrote:
At 4/22/2010 5:34:25 PM, omelet wrote:
Plus, what about all those people who are infertile and incapable of breeding?
That also causes problems with a consistent application of the primary "species" definition.

It's not a matter of whether or not each individual can reproduce. Being infertile does not make one inanimate.

I think you will find that was the point of his post. :P
sherlockmethod
Posts: 317
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4/22/2010 10:28:16 PM
Posted: 6 years ago
Ernst Mayr's book "This is biology" shows some of the arguments for the definition of life and the struggle to find the right term. This is a great subject involving levels of organization and other matters. The book is an easy read for the most part. I recommend it as a starting point.
Library cards: Stopping stupid one book at a time.
Kleptin
Posts: 5,095
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4/24/2010 9:55:59 PM
Posted: 6 years ago
Prions engage in the same type of activity viruses do, and they're essentially nothing more than protein chains.
: At 5/2/2010 2:43:54 PM, innomen wrote:
It isn't about finding a theory, philosophy or doctrine and thinking it's the answer, but a practical application of one's experiences that is the answer.

: At 10/28/2010 2:40:07 PM, jharry wrote: I have already been given the greatest Gift that anyone could ever hope for [Life], I would consider myself selfish if I expected anything more.
Ragnar_Rahl
Posts: 19,297
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4/24/2010 10:16:29 PM
Posted: 6 years ago
Infertile organisms still reproduce their own cells do they not?
It came to be at its height. It was commanded to command. It was a capital before its first stone was laid. It was a monument to the spirit of man.
belle
Posts: 4,113
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4/25/2010 5:07:09 AM
Posted: 6 years ago
At 4/24/2010 9:55:59 PM, Kleptin wrote:
Prions engage in the same type of activity viruses do, and they're essentially nothing more than protein chains.

meh, prions don't really infect cells, they just induce normal proteins to take on the abnormal configuration... and then stick together. which is what causes the havok. they don't need to get themselves replicated the way a virus does, or even necessarily break into cells at all. depends on the distribution of the normal proteins.
evidently i only come to ddo to avoid doing homework...
Kleptin
Posts: 5,095
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4/25/2010 9:55:55 AM
Posted: 6 years ago
At 4/25/2010 5:07:09 AM, belle wrote:
At 4/24/2010 9:55:59 PM, Kleptin wrote:
Prions engage in the same type of activity viruses do, and they're essentially nothing more than protein chains.

meh, prions don't really infect cells, they just induce normal proteins to take on the abnormal configuration... and then stick together. which is what causes the havok. they don't need to get themselves replicated the way a virus does, or even necessarily break into cells at all. depends on the distribution of the normal proteins.

Note that I didn't say "infection". I said "activity". The activity is the change of normal body components into a form that will carry on the chain.

Whether or not a prion engages in the act of cellular invasion is irrelevant. What we're talking about right now is the use of replication as a life-defining characteristic.

For all intents and purposes, the hijacking of cellular machinery to produce more viruses and the conversion of normal protein into a damage-inducing misfolded protein are identical.
: At 5/2/2010 2:43:54 PM, innomen wrote:
It isn't about finding a theory, philosophy or doctrine and thinking it's the answer, but a practical application of one's experiences that is the answer.

: At 10/28/2010 2:40:07 PM, jharry wrote: I have already been given the greatest Gift that anyone could ever hope for [Life], I would consider myself selfish if I expected anything more.