Difference between living and dead cells

Discussion in 'Biology & Genetics' started by madiyaan, Apr 7, 2007.

  1. madiyaan Registered Member

    Messages:
    1
    Hello,

    I don't have a strong biology background but do have an interest in biology (let's just say it's curiosity). Do present-day scientists know the difference between a living cell and a dead cell (is there a difference chemically)? How about the difference between a living organism and a dead organism (when can an organism be officially called "dead"?) Are there any intermediate states between living and dead? Does the protein structure get altered? Can scientists somehow undo the process (is it a reversible chemical process)?

    Thank you,
     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. globenstein Registered Senior Member

    Messages:
    74
    The requirements for something to be "alive" are the followings:

    1. Homeostasis
    2. Organization
    3. Metabolism
    4. Growth
    5. Adaptation
    6. Response to stimuli
    7. Reproduction

    Since anything that doesn't have all these characteristics is not alive, I'd say there's no intermediate state (except for rare exceptions where reproduction is not possible, such as mules or ant workers).
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. Read-Only Valued Senior Member

    Messages:
    10,296
    Actually, the third one is quite enough by itself. If there is no metabolism present there is no life present, either.
     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. S.A.M. uniquely dreadful Valued Senior Member

    Messages:
    72,822
    I would say life is signified by metabolism, adaptation and reproduction.
     
  8. S.A.M. uniquely dreadful Valued Senior Member

    Messages:
    72,822
    One can simulate metabolism in incubations using substrates and enzymes.
     
  9. Read-Only Valued Senior Member

    Messages:
    10,296
    Correct.

    Please Register or Log in to view the hidden image!

    But as you said, it's a simulation. Therefore, not life.
     
  10. S.A.M. uniquely dreadful Valued Senior Member

    Messages:
    72,822
    Granted, but it begs the hypothesis that metabolism can exist independent of life and may have, prior to biogenesis.

    Please Register or Log in to view the hidden image!

     
  11. arauca Banned Banned

    Messages:
    4,564
    Granted, but it begs the hypothesis that metabolism can exist independent of life and may have, prior to biogenesis.

    So what remains is reproduction, then life is actually in the sperm?
     
  12. valich Registered Senior Member

    Messages:
    3,501
    An eunuch is a fully functional living human being, as are the other exceptions mentioned above that are life forms: hybrids, worker ants, etc. Cancel reproduction as an apriori criteria. I'd narrow it down to just metabolism and response to stimuli. At that point there's a very fine line as to what constitutes life or death. Take for example a person in a coma. They may or may not return to a fully functional state, or may eventually be declared brain dead, and then declared dead. It starts to get into a moral issue.

    Are there any intermediate states between living and dead? Yes. How about the dormancy period in seed germination: some live, some die, some germinate. People too can be temporarily dead and be brought back to life through such means as mouth-to-mouth resuscitation and/or CPR. So where do you draw the line? It gets to be a moral issue. The cells are still alive, but the wholistic organism is dead.
     
  13. S.A.M. uniquely dreadful Valued Senior Member

    Messages:
    72,822
    Your argument is incorrect, because an eunuch is not the sole representative of the human being, if he were, the species would be over.
     
  14. valich Registered Senior Member

    Messages:
    3,501
    The question posted was: "How about the difference between a living organism and a dead organism (when can an organism be officially called "dead"?)." I am giving an example where reproduction is irrelevant in classifying an organism as living or dead.
     
  15. Idle Mind What the hell, man? Valued Senior Member

    Messages:
    1,709
    Yes, but the requirements for what is alive does not answer the question. Those criteria are where the line is drawn between living and non-living -- e.g. a virus. How many of those criteria does a viral particle meet? How many does a single celled organism meet? Etc.

    Nobody is going to argue whether a eunuch is alive or not. They are still human, and we know humans are alive. Humans meet all the required criteria put forth by that list. It is general, and not specific. Don't over-complicate things.

    Yes, there certainly is a difference chemically between a dead cell and a live one.
     
  16. invert_nexus Ze do caixao Valued Senior Member

    Messages:
    9,686
    A eunuch may not be able to reproduce with another human to create another human, however he is composed of cells that undergo mitosis.

    I'm not saying that reproduction is a criteria of life, however. More like it's a criteria for potentially successful life. If a molecule is unable to replicate itself, then no matter how many fancy tricks it can do, it is meaningless in short order.
     
  17. Maddy Registered Member

    Messages:
    1
    what is the answer of
    Do present-day scientists know the difference between a living cell and a dead cell (is there a difference chemically)?
     
  18. Aqueous Id flat Earth skeptic Valued Senior Member

    Messages:
    6,152
    Hello, welcome to SciForums.

    You resurrected a 5-year old thread. So speaking of living vs dead...

    Please Register or Log in to view the hidden image!



    There are several ways to dig into this. You might want to start with the basics:

    http://en.wikipedia.org/wiki/Life
     

Share This Page