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Abiognesis: excerpt from a book.

  1. Aug 26, 2011 #1
    Hello!
    I'm reading a book titled Abiogenesis: How Life Began. The Origins and Search for Life. I was hoping someone would be able to explain the following. Its based on the theory that life emerged around hydrothermal vents:

    "The real entropic output of life then is not the complex organic molecules that constitute life and enable the processing, but those waste products closer to equilibrium than the reactants, such as methane, acetate and certain sulfides and oxides as well as the recalcitrant stable organic molecules such as the hydrocarbons that tend to be interred within the sedimentary piles." (my own emphasis).

    This makes no sense to me. Particularly the bolded part.
    Any help at all is appreciated.
    Thanks in advance.
     
  2. jcsd
  3. Aug 26, 2011 #2

    Ryan_m_b

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    The exert is talking about entropy, in that respect is it saying that the waste products increase the entropy of the system. Do you understand this?

    Also if you are interested in abiogenesis this video is very good



    https://www.youtube.com/watch?v=U6QYDdgP9eg
     
    Last edited by a moderator: Sep 25, 2014
  4. Aug 26, 2011 #3
    Thanks for the response Ryan. I appreciate the principle of entropy, but this bit in particular I am confused about:

    "those waste products closer to equilibrium than the reactants"

    I am not sure what reactants the sentence is referring to. Surely the equilibirum is dependent on the reactants as well. I do not see how the waste products can be closer to equilibrium without the reactants also approaching equilibrium...
     
  5. Aug 26, 2011 #4

    Ryan_m_b

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    Perhaps it meant "those waste products closer to equilibrium than the reactants they came from". So it's comparing the waste products of the reaction to the reactants that were there at the start, does that make sense?
     
  6. Aug 26, 2011 #5
    Entropy as used here means there's less energyin in a system available to do work. That is, complex molecules have been metabolized leaving waste products with less avalable energy.
     
    Last edited by a moderator: Aug 26, 2011
  7. Aug 26, 2011 #6
    Thanks again Ryan.
    So its a comparison across time? As in: there is some conc of the reactants at t=0, the reaction proceeds, approaching equilibrium, and the waste products are being considered at this later time, comparing the conc of the waste products at this later time to the conc of the reactants at t=0. Which has an associated increase in entropy, which apparently drives the process to a large extent.
     
  8. Aug 26, 2011 #7

    Ryan_m_b

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    This is not true and misleading. There is a wealth of scientific evidence and study pertaining to abiogenesis. You are displaying an ignorance here, whilst there is no comprehensive Theory of Abiogenesis there is far more investigation than simply "pedantic speculation".
    I guess so, that's all I can make from that statement.
     
  9. Aug 26, 2011 #8
    Thanks Jorge, not experts but excerpt, as in a short extract.
    Can't entropy be associated with an increase in energy. Indeed, the book does state a movement towards less energy, but can that really be taken from the use of the word entropy here?
     
  10. Aug 26, 2011 #9
    Thanks Ryan, thank goodness its not only me (that finds it ambiguous), then!
     
  11. Aug 26, 2011 #10
    Think so nobahar - entropy is a property that can be used to determine the thermodynamic energy in a system available for work. I had a bit of trouble understanding what this has to do with abiogenesis in this brief extract.
     
  12. Aug 26, 2011 #11

    Pythagorean

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    Work is a physics term. biological systems are physical systems. The system must take matter from the environment and metabolize it. It then uses that matter (and energy, coincidentally) to send signals, build structures, replicate itself. This all requires "work" to move matter in specific ways like this.

    An example of energy that's not work would be heat byproduct. The heat must go from source to sink for us to extract energy in a usable way. The byproduct is the heat that doesn't go into work, but goes to the sink (see image in link below)

    http://en.wikipedia.org/wiki/Heat_engine
     
  13. Sep 2, 2011 #12

    bobze

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    Ryan is on the right path here. They are referring to, I believe, that more complex organics can build up over time (particularly hydrocarbons) through various chemical processes. Life then in this instance, though complex itself, would increase the total entropy of the system by metabolizing those more complex natural molecules. While the life maybe "complex", remember that it is the net change here we are worried about. Its important to remember that even in something like a theoretical isolated system you can have local decreases in entropy, so long as your net change is 0 or increasing.

    There seems to be an idea, a hypothesis if you will, growing in popularity amongst prebiotic chemists involving RNA polymerization and UV light--Which when RNA polymerizes in the presence of UV light it turns out to be good at increasing the entropy of the system. This maybe one of the ways that earlier "trial and error" nucleotide permutations eventually formed the first replicators.

    Edit: Just to address something that seems to have been taken care of so everyone (particularly the OP) is getting good information; there certainly are experts when it comes to abiogenesis. Prebiotic chemistry is their field of study and there are many cataloged facts and observations left over from those yesteryears that those experts and scientists explain and seek to explain. Certain processes have left more information about the early earth than many people realize and there is data there for science to be preformed on. Contrary to certain posters ill-founded beliefs, such areas are not a lot of "guess work". Little self education could go a long way.
     
  14. Sep 2, 2011 #13
    Thanks for the response bobze.

    Can you elaborate on this bit? According to the University of Southern Mississippi website, polymerization is almost always associated with a decrease in entropy.
     
  15. Sep 3, 2011 #14
    Equilibrium is associated with the entire reaction and not only its reactants or products. But 'equilibrium' over here does not talk about any reaction, but a state of high entropy or a more 'probable state'.


    Yes while the polymerization does decrease the local entropy, the energy released in the reaction increases the entropy of the surroundings, resulting in a net increase in entropy of the system. That is what Bobze wrote.
    {emphasis mine}
     
  16. Sep 3, 2011 #15
    Lemme' take a shot at that ok?

    You'll agree that at equilibrium, we have the maximum entropy. The second law has driven the system to maximum disorder and free-energy to do work is at a minimum. But life is an ordered system that is constantly being bomb-barded by the second law to become disorded. To stay alive then, life must continuously feed on order in the form of ordered molecules. Those ordered molecules represent negative entropy. Life feeds on this order by "riding" the free-energy trajectory during the process of converting these high-ordered molecules into smaller, more disordered ones like water and CO2. These smaller, low-energy molecules represent an increase in entropy and thus are closer to equilibrium. Life, to persist then, creates entropy during this order-conversion and it does so by pushing chemical processes closser to equlibrium like in the conversion of a high-ordered sugar molecule to low-order and greater entropy of water and CO2

    If it were a test question, that's what I'm goin' with. Figure it's a B maybe.
     
    Last edited: Sep 3, 2011
  17. Sep 3, 2011 #16
    Dispute there are "experts" in a phenomenon no one understands or has replicated in whole or in validated part. There are hypotheses only for abiogenesis.
     
  18. Sep 3, 2011 #17

    Ryan_m_b

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    An expert is simply someone who has extensive knowledge of the field (most often because they have long time experience working within it) regardless of how complete the field is.
     
  19. Sep 3, 2011 #18
    You kinda' don't believe it huh? Chemistry is really very beautiful. Life too. And if you study them for a long time, things begin to emerge about them. Your ideas about them become more than just the sum of all that you've learned. It's a slap in the face to chemistry to doubt it can, all by it's lonesome, create something wonderful like life. That's part of the beauty and that's part of what emerges I think. But it's not easy for someone to just blindly accept that without going through the painstaking synthesis of reaching that conclusion through emergence. There are things you can only know by living a long time and for me at least, I find it easy to accept that chemistry can create life all by itself.
     
  20. Sep 3, 2011 #19
    Extensive knowledge? In chemistry associated with hypotheses but not in abiogenesis where science sees no theory prevailing.
    An expert in building and understanding roads can tell you nothing about the destination until he gets there.
     
  21. Sep 3, 2011 #20

    Ryan_m_b

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    (Emphasis mine)

    Why would he need to? He's an expert in building and understanding roads.
     
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