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Starting a new thread as a way to kill boredom............................
So, do you guys believe virus, prions and RNA's living? i have read multiple article on wikipedia that seems to show different sides to this problem, but no sides have really won
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Viruses and prions aren't alive, but they almost are. Essentially, they are complex proteins; a strand of RNA, a complex protein wrapped in a shell of simpler protein.
What would your definition of life be?
Prions are proteins that contain no genetic information, the only thing close to a living being it does is replicate; likely by molecular interactions at the right spot, but it seems the procedure is still unknown. To me, this is not life; just an interacting protein sequence.
RNA is a molecule. It can act as both genetic coder and enzyme, so it important to life; but I don't consider it alive.
Viruses are likely more difficult to categorize... they are replicating units containing both proteins and genetic molecules, and are subject to selection pressures; yet they have no metabolism and cannot replicate alone. I think I would consider it not alive in the traditional sense, but certainly as a class of biological units that are on the verge of life.
Who knows, maybe they are the oldest "living fossils", maybe they arose at the same time as the very first living cells without making the last step towards life?
Viruses would be classified as living if they could reproduce by themselves, as the rest of all organisms can do. Seeing as how they require other organisms to complete this process, they are just shy of classified as being alive. They have everything else, but not that.
Yet ironically, viruses win at life, even though they aren't alive, because some viruses have been found at age 65 million.
What would your definition of life be?
Personally, i would consider anything than can reproduce and replicate itself and have a detailed substructure to be "alive".
Anyway i have found the contradiction in what wikipedia said. what do you think this :
. In particular, it is sometimes found that the Hadean eon is subdivided into the Cryptic era and Basin Groups 1-9 (which collectively make up the Pre-Nectarian), and the Nectarian and Lower Imbrian. The first lifeforms (self replicating RNA molecules, see RNA world hypothesis) may have evolved on earth around 4 bya during this era.
.....meant? because according to the definition of life in 09philj's link, the bolded sentence directly contradicts this
Personally, i would consider anything than can reproduce and replicate itself and have a detailed substructure to be "alive".
1) What about obligate parasites that need a host to reproduce?
- IMO, Viruses rely on the replication machinery of a living cell to reproduce, while parasites have their own reproductive organs; they simply rely on other factors like resources or heat.
2) Define "detailed substructure". Are the structure proteins making up a virus' shell too simple for life?
1) What about obligate parasites that need a host to reproduce?
I would consider obligate parasites (viruses) alive, simply because it has the ability to reproduce, even if if he used other cells to replicate. other reasons as to why i take such stance is because i have been taught that the basic purpose of life for any organism is to reproduce and to propagate itself using whatever means necessary.
2) Define "detailed substructure". Are the structure proteins making up a virus' shell too simple for life?
a detailed substructure is, as it names suggest, a very complex inside structure of something. that "something" must have a way to maintain that complexity ( in normal conditions) and to keep it from breaking apart into simpler components. It may be better to define this as having a negative entropy, as most of anything alive is far more complex than anything not living or were once alive
a virus shell is far, far more complex than anything that is not alive. a shell of numerous proteins and fat which combine to make the bi-layer membrane is very complex and consist of several micro structures like docking proteins that add the apparent complexity of a viruses shell
I would consider obligate parasites (viruses) alive,
Sidenote: I do not consider viruses to be parasites, but rather pathogen agents. An obligate parasite is for example a tapeworm.
And while reproduction is of course important to continuing life, I personally do not consider the mere fact of replicating to be sufficient in and on itself. The difference of being an organism with its own cells and metabolism that needs a host, compared to a structure that needs something else for basically everything and lacks any metabolic process or any kind of machinery, really, is big enough to draw the line. But that's just me.
a virus shell is far, far more complex than anything that is not alive. a shell of numerous proteins and fat which combine to make the bi-layer membrane is very complex and consist of several micro structures like docking proteins that add the apparent complexity of a viruses shell
There are also far more simple viruses out there. What about those?
far more simple viruses
At their most simple, RNA in a protein coat.
I do not consider viruses to be parasites, but rather pathogen agents. An obligate parasite is for example a tapeworm.
Well we have a disagreement here, because i was taught that virus ARE obligate parasites. He defined "obligate parasites" as anything that requires a host to reproduce.
And while reproduction is of course important to continuing life, I personally do not consider the mere fact of replicating to be sufficient in and on itself
Which is why i added detailed substructure and negative entropy to the mix.
The difference of being an organism with its own cells and metabolism that needs a host, compared to a structure that needs something else for basically everything and lacks any metabolic process or any kind of machinery, really, is big enough to draw the line.
The difference are big, but in my opinion not good enough to disqualify virus as a living object. Because it has a pretty detailed subsystem under the microscope.
There are also far more simple viruses out there. What about those?
All virus have docking proteins and bi-layer semipermeabel membrane, it forms the shell of all viruses
Well we have a disagreement here, because i was taught that virus ARE obligate parasites. He defined "obligate parasites" as anything that requires a host to reproduce.
Anything or any living thing? It's semantics, really, but I just need to make this clear. To me, a parasite is a parasitic organism. A virus is not an organism, it is a pathogen.
The difference are big, but in my opinion not good enough to disqualify virus as a living object. Because it has a pretty detailed subsystem under the microscope.
The difference is enough in my eyes because the virus is a passive structure. It doesn't do anything by itself; transmission, replication... even the docking is just a physical reaction of the structure with the structure of the host cell.
All virus have docking proteins and bi-layer semipermeabel membrane, it forms the shell of all viruses
Not all viruses have such a membrane, and those who do "steal" it from the host cell (basically not every part of the virus is of viral origin).
Anything or any living thing? It's semantics, really, but I just need to make this clear. To me, a parasite is a parasitic organism. A virus is not an organism, it is a pathogen.
anything
The difference is enough in my eyes because the virus is a passive structure. It doesn't do anything by itself; transmission, replication... even the docking is just a physical reaction of the structure with the structure of the host cell.
if it was a passive structure, then it won't be able to replicate or reproduce. just think about it, if the docking WAS just a physical reaction and the adsorption is just a reaction, then that would meant the cell literally have done suicidal attempt to kill itself, and the virus is just an innocent bystander that "happens" to adsorb itself to the cell, "happens" to destroy it's host DNA in the nuclei, "happens" to replicate itself by using the cell's compounds and also "happens" to blow up a cell open. which if i think about is not really logical.
Not all viruses have such a membrane, and those who do "steal" it from the host cell (basically not every part of the virus is of viral origin).
Without a bi-layer semipermeable membrane, the virus itself can't survive on it's own, because it's contents would just spill out of the virus. A docking protein is essential to any virus, because without it, it can't reproduce ( it can adsorb itself to the host cell if it can't cling to it using a docking protein). And now you are telling me that not all virus from the start have those? then how, i ask, that those virus survive, let alone replicate in the first place?
anything
Ok, I'll take that into account...
if it was a passive structure, then it won't be able to replicate or reproduce.
Reproduction=replication in viruses. And yes, it is able to do so, because the host cells do it all; the virus just needs to dock to the cell and inject the RNA strand (with the right chemical structure this happens easily); everything else happens by itself from there on. The strand will eventually be transcribed and copied, the proteins built by the cell, and everything added together. Eventually the cell will be so full of viruses that it simply bursts open and releases them.
Without a bi-layer semipermeable membrane, the virus itself can't survive on it's own, because it's contents would just spill out of the virus. A docking protein is essential to any virus, because without it, it can't reproduce ( it can adsorb itself to the host cell if it can't cling to it using a docking protein). And now you are telling me that not all virus from the start have those? then how, i ask, that those virus survive, let alone replicate in the first place?
Easy there. All viruses have a capsid, a protein coat protecting them. And all viruses have some kind of docking system, or docking proteins. Some viruses additionally take a piece of the host cells lipid bilayer as an additional protection. All I was saying is not all viruses have this lipid bilayer; but that's fine since they still have the capsin.
Reproduction=replication in viruses. And yes, it is able to do so, because the host cells do it all; the virus just needs to dock to the cell and inject the RNA strand (with the right chemical structure this happens easily); everything else happens by itself from there on. The strand will eventually be transcribed and copied, the proteins built by the cell, and everything added together. Eventually the cell will be so full of viruses that it simply bursts open and releases them.
well then, we have a disagreement here. let me list them all.
1. if a foreign object comes inside a cell, then lysosome bodies will engulf and destroy it to pieces using lysozyme enzyme. it will literally destroy the virus RNA, unless it secretes something to counteract this. If the virus is passive, then the RNA/DNA strand would also be passive and not doing anything to counteract the destructive lysozyme enzyme, so the virus infection processes would be stopped in it's tracks right there.
2. even if the passive RNA/DNA can somehow get past these lysosome that form the waste and foreign object cleaning crew, they would not be able to take over the cell machinery unless they destroy the nucleus of the host cell. now, a cell would not just blow up it's own nuclei. the virus's DNA/RNA strand HAD to intervene and secrete DNA destroying enzyme.
3. A cell rupture ( or lysis ) most commonly happen because the virus, having crowded the cell, secrete membrane destroying enzyme.
if a virus was passive, it can't get past all the stages with no problems. it has to be active inside the cell, or the cell would just destroy it using lysosomic bodies. it has to secrete important enzyme or become one if it wants to replicate and that won't happen if the virus is passive
Easy there. All viruses have a capsid, a protein coat protecting them. And all viruses have some kind of docking system, or docking proteins. Some viruses additionally take a piece of the host cells lipid bilayer as an additional protection. All I was saying is not all viruses have this lipid bilayer; but that's fine since they still have the capsin.
Oh, i thought you meant that the capsid itself as it is also a bi-layer semi-permeable membrane. my bad.
Hold on, I think there are a few misconceptions in your post above, but I have to refresh my own knowledge first before I say anything wrong. I'll get back to your post soon.
so some of my point is invalid? well i'll blame it on my good-for-nothing science teacher if there are misconceptions
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