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Thread: Living or Non-Living

  1. #1 Living or Non-Living 
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    What do people think in depth about virus. Is it living or non-living??


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    WYSIWYG Moderator marnixR's Avatar
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    yes


    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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  4. #3  
    Forum Radioactive Isotope skeptic's Avatar
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    Depends on your definition. Some definitions of life are specifically designed to exclude viruses. My own personal opinion, FWIW, is that the key characteristics for life are reproduction and evolution. By that standard, viruses are alive.
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  5. #4  
    Forum Professor Zwirko's Avatar
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    I don't consider the virus particle to be a living entity, but rather something that is somewhat analogous to a spore or a seed. Once inside a cell the virus could maybe be described as living. By focussing on the virus particle alone it's quite difficult to describe viruses as living; thinking about their life cycles makes things get a whole lot fuzzier.

    At one extreme, some have suggested that the infected cell is actually the "virus", with the particle itself just being a way to move from host to host - a form of life that has shed the need to carry around its own cellular machinery and instead uses someone else's.
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    Forum Freshman LordKelvin's Avatar
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    My opinion is that viruses are not alive, only sophisticated molecular machines. Yes they are subject to evolution through mutation/natural selection but that is a consequence of they being encoded by nucleic acid. My opinion is rather pragmatic but I acknowledge that if we dig deep enough the limit between alive/not is fuzzy.

    For exampl, I consider that a virus is not alive because they can't do anything by themselves, but is you look at certain intracellular obligate parasites such as microsporidia, they can't reproduce by themselves either, will remain as an inert spore unless getting to infect a live cell in which to complete its life cycle.

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  7. #6  
    Forum Radioactive Isotope skeptic's Avatar
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    Kelvin

    That is a common view. This question has no obvious and clear cut answer. It is a matter of how you look at things. One reason I prefer to think of viruses as living is that it is very possible they evolved from bacteria by a process of simplification down to the essentials for a parasitic way of life. It would be kind of strange to think of living bacteria evolving into a non living form.
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  8. #7  
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    OK so now let me tell you people that virus is considered as non-living as well as living. No research has proved perfectly that is it really living or non-living. It is considered in some particular terms as living and somewhere as non-living. The most interesting character of virus which makes it living is its Reproduction. But it can not reproduce or even survive outside host's body, which proves it as non-living. I consider and believe it as a simple molecular machine which can not survive on its own....
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  9. #8  
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by Ammad Ahmed
    OK so now let me tell you people that virus is considered as non-living as well as living. No research has proved perfectly that is it really living or non-living. It is considered in some particular terms as living and somewhere as non-living. The most interesting character of virus which makes it living is its Reproduction. But it can not reproduce or even survive outside host's body, which proves it as non-living. I consider and believe it as a simple molecular machine which can not survive on its own....
    Parasites can't survive without a host. Are they non-living? This is not a good way to make the distinction.
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  10. #9  
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    What do mean Mr or Mrs Biologista ??
    Mosquitoes are also parasites, can't they live outside host body ?? Viruses are internal parasites OK ?? It depends that what type of parasite it is actually... I am talking about Viruses(Internal Parasites)... So your opinion isn't correct that,

    "Parasites can't survive without a host. Are they non-living?"

    And if you want a clear distinction of viruses, so they undergo crystallization which is not a phenomena...............
    Regards
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  11. #10  
    Forum Radioactive Isotope skeptic's Avatar
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    I support Biologista on this.

    There are parasitic bacteria that are so simplified by evolution that they have no chance at all of living outside a host body. Yet they are classified as living. So being totally dependent on a host is not a valid criterion.
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    WYSIWYG Moderator marnixR's Avatar
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    remember : current function is not always an indication of past structures
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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  13. #12  
    Forum Professor jrmonroe's Avatar
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    Quote Originally Posted by Zwirko
    I ... consider the virus particle to be ... somewhat analogous to a spore or a seed.
    Hmm ... a self-perpetuating seed ... a very interesting idea.
    Grief is the price we pay for love. (CM Parkes) Our postillion has been struck by lightning. (Unknown) War is always the choice of the chosen who will not have to fight. (Bono) The years tell much what the days never knew. (RW Emerson) Reality is not always probable, or likely. (JL Borges)
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  14. #13  
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by Ammad Ahmed
    What do mean Mr or Mrs Biologista ??
    Mosquitoes are also parasites, can't they live outside host body ?? Viruses are internal parasites OK ?? It depends that what type of parasite it is actually... I am talking about Viruses(Internal Parasites)... So your opinion isn't correct that,

    "Parasites can't survive without a host. Are they non-living?"

    And if you want a clear distinction of viruses, so they undergo crystallization which is not a phenomena...............
    Regards
    Not sure you understood me. You argued that we consider viruses non-living because they can't live or reproduce outside of a host. Sure, there are parasites that can live and reproduce outside of a host, but there are also obligate parasites- as much dependent on their hosts as viruses are- that we consider to be living.

    This doesn't mean that viruses are living, just that the dependence thing isn't a good argument against it.
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  15. #14  
    Forum Professor Zwirko's Avatar
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    I like to focus on the history of a virus, what a virus actually does and what it becomes, rather than just looking - narrowly in my view - at what is more or less an inert, lifeless virion . I've always found it quite remarkable that a virus can enter a cell, reprogram that cell through intricately complex interactions with cellular proteins and enzymatic pathways, and ultimately redirect the cellular protein synthesis machinery, transforming that cell into what is basically a virus-factory. The virus "comes to life" inside the cell, in effect. The virion is only part of the picture and something that is given far too much attention in such discussions when deciding whether or not it meets the requirements of one particular definition of life or not.

    If we want to include viruses among the living we can either change the definitions of life itself to include viruses (if that's what we want to do), or we can change the way we look at viruses. For the latter case, it's clear that the business end of the virus is inside the cell and that the virion is a stage in what can be a very complicated life cycle with a long evolutionary history. Since we can barely describe what it means to be alive or what constitutes an individual, it's no wonder viruses pose such a problem.

    To be honest I think there is no real resolution. Viruses raise more problems, such as what to with things such as viroids, satellite viruses, plasmids, transposons, or bacteria such as Wolbachia and Rickettsia, or organelles such as plastids and mitochondria. It's a minefield.

    It's unfortunate that our penchant for categorising nature into neat little boxes doesn't always map onto the real world so neatly. To me it's not surprising that life has a gray area where things are barely alive or where we struggle to even define them as living. The other end of the spectrum of life may have its own, equally fascinating, grey area of debate one day too when intelligent life finally abandons biology completely.
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  16. #15  
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    Look you didn't understand me.... I wanted to say that viruses are neither living nor non-living, in support of that I presented the above examples of biological phenomena of living or non-living......
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  17. #16  
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    While you folks are WAY out of my league... I venture to say.... isn't a virus a hunk of rna in a protein coat? And, if the host dies, the virus dies? Perhaps then the virus may evolve, per se, attenuates (?) for a more symbiotic relationship? Reading medical literature back in the early 80's I noticed many articles started out with how ....now that we don't die of infectious diseases so much, we are living longer to die of chronic diseases..... Then, Aids/HIV came along. Did we go full circle? LIke I said, you folks (this whole forum) is way out of my league. Don't eat me alive. Thanks
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  18. #17  
    WYSIWYG Moderator marnixR's Avatar
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    in my definition, life is characterised by descent with modification
    using that definition a virus is life
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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  19. #18  
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    I heard once that by definition fire would classify as life: it needs oxygen, consumes, leaves waste.....( meant only to be amusing)
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  20. #19  
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by Epidemos
    I heard once that by definition fire would classify as life: it needs oxygen, consumes, leaves waste.....( meant only to be amusing)
    It does not undergo descent with modification though...
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