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Thread: Oxygen-based Life...?

  1. #1 Oxygen-based Life...? 
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    I'm sure this question has been asked before, but why is oxygen critical to sustaining life? Is there a possibility that there is life beyond Earth that is dependent on another element? From what I've read, apparently oxygen is a catalyst for life, but is it possible that another form of life is able to live off of a different element?


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    Forum Cosmic Wizard i_feel_tiredsleepy's Avatar
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    Lot's of anaerobic life exists on Earth and Oxygen is toxic to most of them, oxygen is the terminal electron acceptor for all eukaryotic life and a good portion of bacteria. However, many less electronegative molecules can suffice but oxygen happens to be the best suited as an electron acceptor because oxygen is abundant on Earth as a result of photosynthesis and is highly electronegative.


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    Forum Masters Degree Numsgil's Avatar
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    Or in layman's terms: Oxygen is abundant (because it can be stripped from water and CO2), and highly reactive.

    Other biochemistries might exist, though. See this wiki article.
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  5. #4 Re: Oxygen-based Life...? 
    Forum Cosmic Wizard spuriousmonkey's Avatar
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    Quote Originally Posted by npaulaus
    I'm sure this question has been asked before, but why is oxygen critical to sustaining life? Is there a possibility that there is life beyond Earth that is dependent on another element? From what I've read, apparently oxygen is a catalyst for life, but is it possible that another form of life is able to live off of a different element?
    It isn't. It's a 'recent' invention.
    "Kill them all and let God sort them out."

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  6. #5 Re: Oxygen-based Life...? 
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by npaulaus
    I'm sure this question has been asked before, but why is oxygen critical to sustaining life? Is there a possibility that there is life beyond Earth that is dependent on another element? From what I've read, apparently oxygen is a catalyst for life, but is it possible that another form of life is able to live off of a different element?
    Well, probably not a "catalyst" for life. But a nice reactive element like oxygen certainly makes more energy available to life. Early life wouldn't have needed it so much (and there wouldn't have been much of it about when life first started), and as i_feel_tiredsleepy says, we can see loads of modern examples of life forms that do not use oxygen at all. What they all have in common though, is a much lower energy requirement than us hyperactive animals.
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    Forum Masters Degree organic god's Avatar
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    I think water is one of the critical components of life rather than oxygen
    everything is mathematical.
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    Forum Cosmic Wizard spuriousmonkey's Avatar
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    Oxygen is a poison. It was a byproduct of early lifeforms and it changed the way the biosphere was organized. Adapt to the poison or find a niche where it can't reach you.

    Oxygen didn't come first. Life never depended on it. Till some asshole organisms decided to spew the atmosphere full of oxygen.
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    There was a recent discovery of an Arsenic fixing bacteria...Not only is it not toxic, but it uses it in it's metabolism!
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  10. #9  
    Forum Cosmic Wizard spuriousmonkey's Avatar
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    jesus christ.

    The biosphere of earth never had oxygen similar to the current content. The oxygen levels were raised to current levels and beyond due to the emergence of a specific type of organisms.

    That meant a complete destruction of the old organization of the biosphere since to most life oxygen was actually toxic.

    They retreated to their current niches and expanded the niches later on of course.
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  11. #10  
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by organic god
    I think water is one of the critical components of life rather than oxygen
    Yeah, all life that we know of be it aerobic or anaerobic uses water as a solvent. As far as I know, all of our idea on abiogenesis also rely on liquid water.
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  12. #11  
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    Quote Originally Posted by TheBiologista
    water as a solvent
    It seems mild and harmless to us, but water could be a horribly destructive compound to alien life. If they were no smarter than us, and viewed this world, they'd think, "hostile, absolutely inhospitable."
    A pong by any other name is still a pong. -williampinn
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    Forum Ph.D. Raziell's Avatar
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    Quote Originally Posted by spuriousmonkey
    Oxygen is a poison.
    Why do our bodies need oxygen to stay alive if oxygen is a poison? Or is there something else then oxygen that also benefits us from the act of breathing?

    If oxygen is a poison, wont that mean that we shouldve adapted our bodies through evolution to resist it? If we have adapted to depend on it instead, it would mean we are forced to live with the poision forever.

    Is it possible through science to manipulate our bodies to create offspring that dont need oxygen to survive?

    Im confused and clueless, but my curiosity is tearing me apart >.<
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  14. #13  
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    He means oxygen is poisonous to the original life. Imagine if animals urinated much much more than they do, what would happen to the present biosphere and what radically new organisms could thrive in that.
    A pong by any other name is still a pong. -williampinn
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  15. #14  
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by Pong
    Quote Originally Posted by TheBiologista
    water as a solvent
    It seems mild and harmless to us, but water could be a horribly destructive compound to alien life. If they were no smarter than us, and viewed this world, they'd think, "hostile, absolutely inhospitable."
    I dunno about that- we look at worlds like Titan and think "that's a good spot for life". There's an ammonia/water mixture mantle beneath a thick layer of ice, not to mention lakes of liquid hydrocarbons. It's not hard to imagine alternative life chemistries that use ammonia or organic solvents instead of water. They'd be quite remarkably different from the life we are familiar with, mind you.
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  16. #15  
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    I think we're agreeing.
    A pong by any other name is still a pong. -williampinn
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    Forum Cosmic Wizard i_feel_tiredsleepy's Avatar
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    Yes it is quite evident that oxygen caused mass extinction early on in the history of life, most oxygen using organisms also have catalases and antioxidants that help deal with the nasty consequences of being around oxygen. Photosynthesis relies on the enzyme RuBisCo (ribulose bisphosphate carboxylase) to fix carbon dioxide, however this molecule is heavily inhibited by oxygen. This suggests that the photosynthetic system evolved prior to oxygen concentration in the atmosphere being a problem. Plants have some very clever ways to get around this problem like compartmentalisation and temporal separation of the light dependent and independent reactions. Like spurious said, life would have retreated to oxygen free niches until some organisms evolved to first tolerate oxygen and then to utilize it.
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  18. #17  
    Universal Mind John Galt's Avatar
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    Quote Originally Posted by Pong
    I think we're agreeing.
    This is an internet forum. You are not allowed to agree.
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  19. #18  
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    It has to do with oxidation reduction potential. Transferring electrons to oxygen is a much more favourable reaction than transferring them to other common electron acceptors. For example:

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    Quote Originally Posted by i_feel_tiredsleepy
    long paragraph i didn't repeat just because you can go up to read it.
    To build upon what you said, if you follow the writings of a person I know pretty well, apparently post-ediacaran life really took hold strongly by living around hydrothermal vents, entire communities of more than just weird crabs, shrimps and of course pogonophorans.
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  21. #20  
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    Interesting. I feel much smarter after reading this thread.
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