From my understanding, If you are to accept cell theory as is, then viruses are not to be considered living as all living organisms consist of one or more cells. A virus is not a cell and does not consist of any cells. To call something life, it must contain DNA/RNA, so is are viruses living or not living?
They can replicate and spread...depends on how you define 'living' I guess...or you have to accept cell theory.
It depends on how you define living, as already mentioned. It's not so much that viruses aren't cells that make them not "alive" by conventional definitions, but rather that they cannot replicate on their own-- they require a host cell to provide the necessary mechanical machinery to replicate. "Life" requires that the cell be able to reproduce and pass on heritable information on their own. That's my understanding at least....I'm not a virologist.
To me, if it self replicates and evolves, then it is alive. The opposite of simple chemical reactions which is subject to entropy. (Yes i know life is subject to "entropy" i just didnt know how to word it) Life is able to sustain its own chemical reaction, and even expand it By this definition dna is not required Sent from my LG-E739 using Grasscity Forum mobile app
Viruses do not have the ability to reproduce reproduce on their own. They are not living Sent from my iPhone using Grasscity Forum mobile app
Virus's are DNA or RNA strands..... When you have that info the definition of life or not seems irrelevant. They are chemicals doing what they do like we are chemicals doing what we do
What if....an animal evolved that couldn't reproduce on it's own....like it had to inject DNA into a sacrificial organism or something?
dont we all kinda do that? not that women are sacrificed....but we certainly arent reproducing asexually. also, mules cant reproduce.
I was envisioning something like it injects DNA into a cell of the other organism, and that DNA alters it to where it changes the entire organism into another one of the injecting organisms. Almost like a zombie virus of some type I guess lol
I think that's more or less what a virus does... True, but their cells can replicate and pass on genetic information.
This is a question that has intrigued microbiologists for quite some time. As other people have mentioned, currently viruses aren't considered living organisms. Due to their relatively simple structure, they're somewhere between large molecules and the simplest of biological life. When viruses aren't in the process of infecting a cell, they appear no different than any other molecule which have no metabolic activity. It's when they come into contact with a potential host cell that their "liveness" comes into play. Given these two disparate states, it's hard to permanently classify viruses either way but scientists seem to have favored viruses as non-living. There are of course other aspects to take into account. Two of the most interesting to me are the existence of giruses and virophages along with the existence of non-viral obligate intracellular pathogens. Giruses, as the name implies, are giant viruses with sizes comparable to small bacteria and they have a large genome to boot. Some giruses have even been found to possess genes for antibiotic resistance. They are also susceptible to infection by other viruses, virophages, which can "sicken" the giruses thereby reducing its ability to replicate. The fact that viruses need a host cell to replicate is often used to strip them of "living" status but there are also other pathogens which also depend on a host cell for replication and metabolism. There are multiple species of bacteria, protists, and fungi which are heavily dependent on a host cell and can't complete their life cycle without it yet they are all considered to be living. Chlamydia is the one that's probably most familiar to most people. It's also important to note that viruses are subject to evolutionary principles, such as natural selection, just like "living" organisms are. Im conclusion, they aren't considered living but I think they deserve something more than simply being "non-living".
I disagree. Viruses needing to find host cells is no different than humans needing to find food. Humans cannot reproduce on their own either. You need a mate. You need oxygen. You need food and water. Sent from my LG-E739 using Grasscity Forum mobile app
But when you look for a mate you don't steal their replication machinery to reproduce because you don't have any Sent from my iPhone using Grasscity Forum mobile app
I'm talking the whole organism is changed, not just a portion of it's cells. Also a virus is just a strand of DNA. I talking like what if a cat or something suddenly evolved some capability for it's genes to leach into another organism and turn it into a cat also
Well at this point we are just drawing very thin lines in the trchnical definition of "life" Sent from my LG-E739 using Grasscity Forum mobile app
I think you highlight the root of why viruses aren't considered living - they have no metabolism, and they do not mate with each other. But if you consider the things djsmokebowls mentions such as how chlamydia are in the same boat, then you start to agree that they should fall into a separate class between "non-living" and "living".