The Origin of DNA ? NASA SAYS SPACE .

Discussion in 'Alternative Theories' started by river, Feb 19, 2018.

  1. river

    Messages:
    11,058
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. exchemist Valued Senior Member

    Messages:
    7,334
    Not DNA.

    Building blocks.

    Sort of like the difference between a brick and a house.
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. river

    Messages:
    11,058
    So your saying that in space , what builds DNA , the building blocks of DNA , are separate ?
     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. DaveC426913 Valued Senior Member

    Messages:
    9,198
    Yes. Nucleotides are the "bricks" of DNA. Essentially, they are the foundation for the base pairs
    that, in bulk, encode the genetics in DNA.

    The nucleotides may have formed in space - that does not suggest that DNA itself formed in space.
     
  8. river

    Messages:
    11,058
    Yet so far as I have found , none are found in Nature in free form , meaning not by themselves . The bricks , as you call them , Dave , a foundation of DNA , are not found independent of the other base pairs .
     
  9. exchemist Valued Senior Member

    Messages:
    7,334
    The link provided in the OP explains what kind of building block has been found. These are, apparently molecules such as adenine, guanine etc.

    These are not nucleotides, or even nucleosides, but some of the components of these - the naked forms of the individual "bases" found in the DNA structure.

    DNA, being such a highly complex structure, can be seen as made up, like a car, of various sub-assemblies (nucleotides), each of which involves further sub-assemblies (nucleosides, phosphate groups) and each of these is itself made up of many components, one of which is a "base", itself a fairly complex polyatomic molecule - by the standards of interstellar space at least.

    By way of example, more on adenine here: https://en.wikipedia.org/wiki/Adenine This refers to the Nasa finding, which dates from 2011 apparently. I find it interesting that they say it has complex photochemistry that helps explain its survival under UV light exposure. (I'd like to know more about that - though obviously as it is a 2-ring heterocyclic aromatic compound, it would be expected to have a number of interesting options in its excited states.)
     
  10. river

    Messages:
    11,058

    I'd like to know more about that - though obviously as it is a 2-ring heterocyclic aromatic compound, it would be expected to have a number of interesting options in its excited states.


    Why , what is it about being a , 2-ring heterocyclic aromatic compound , that stirs your curiosity , enough to know more about this , compound ?

    I would like to know .

    river
     
  11. DaveC426913 Valued Senior Member

    Messages:
    9,198
    On Earth. A warm and chemically very active cauldron. It would be pretty much impossible for a given nuceolotide not to be incorporated into some passing form of life.

    That says nothing about the vacuum of space (such as in an asteroid) - where active molecules are few and far between, and temps are far, far below any activation temperature. They can't build up into proteins.

    i.e. nucleotides and DNA are pretty much found (and not found) exactly where you'd expect them to be found (and not found).
     
  12. exchemist Valued Senior Member

    Messages:
    7,334
    I have not found more on adenine but I did find this interesting paper suggesting that the base pair guanine-cytosine as arranged in DNA has a much broader UV absorption band than other possible arrangements: http://www.pnas.org/content/pnas/102/1/20.full.pdf

    This suggests that the lifetime of the excited state formed by UV absorption is far shorter for this arrangement than for others, due to internal conversion, that is, non-radiative ways of redistributing the energy and returning the molecule to the ground state. (Due to the Uncertainty Principle, a short lifetime implies an uncertainty in energy, hence a broadening of the absorption band.)

    The authors suggest that this would make the base pair in its DNA arrangement more resistant to degradation by UV than expected, enabling it to hang around longer for other reactions to occur. Cool stuff.
     
  13. nebel Valued Senior Member

    Messages:
    1,332
    perhaps chemistry at it's most basic level is primed for life in space, like the lengthening telomeres on chromosomes of astronauts in orbit. (see "primed for life" topic, Exobiology)
     
  14. Gawdzilla Sama Valued Senior Member

    Messages:
    2,802
    The Daily Mail will be talking about "Alien DNA found on Earth!"
     
  15. exchemist Valued Senior Member

    Messages:
    7,334
    I'm not sure that means anything. Chemistry is a consequence of physics: it is what it is.

    I think it is probably more useful to say that the chemistry of life may have arisen the way it has due to the ability of certain strcutures to withstand the early environment - a form of pre-biological natural selection, if you like.
     
  16. river

    Messages:
    11,058

    Disagree

    Chemistry is about reactions of physical things to physical things . Physics is the consequence of these reactions .
     
  17. exchemist Valued Senior Member

    Messages:
    7,334
    Typically half-witted contribution.
     
  18. DaveC426913 Valued Senior Member

    Messages:
    9,198
    No. There are no reactions of things to other things without physics.

    Physics occurs whether or not chemistry occurs.
    Chemistry does not occur without physics there to make it occur.
    Chemistry is an emergent property of physics.
     
  19. billvon Valued Senior Member

    Messages:
    14,143
    Nope. Physics underlies chemistry, not the other way around.
     
  20. river

    Messages:
    11,058
    Agreed

    Cosmic Plasma's , ionization of electrons and protons is physics .
     

Share This Page