Prebiotic Notes

Discussion in 'Health and medical' started by Tomhendricks474, Jan 30, 2004.

  1. Here's some interesting notes that may connect up to my origin scenario.

    1. Collision is important for hybridization. If, as I suggest, there was an h-bond world where the
    sun cycle was exactly that which denatured nucleotide strands completely at the high end and then
    annealed them into novel hybrids at the low end. And selection was on the variant best able to
    survive. THEN Where there was the most nucleotides, there would be the most chance for collision
    and annealing.
    2. Also any paired strand that did not completely denature in the highest heat of the day, would be
    the first to anneal or zip up. And it would do so very quickly - thus giving it a selective
    advantage.
    3. Complimentary bases will zip up faster in the annealing part of the cycle. That suggests that
    whatever was the most repetitive code in the nucleotides would also be the more likely to anneal,
    and more likely to anneal quicker and more often.
    4. There are different levels of thermal stability. Molecular Bio by Friefelder lists three in order
    from most to least stable: double stranded DNA, single stranded DNA, free bases. That suggests
    that each is more likely to survive a heat cycle than that that follows it on the list
    5. One phenomenon of DNA is breathing in which double stranded regions frequently open to become
    single stranded bubbles. The same text says, "Note that since a GC pair has 3 hydrogen bonds and
    an AT pair has only two, breathing occurs more often in regions rich in AT pairs than in regions
    rich in GC pairs." A good ex. of this is tRNA today. Note the GC rich stems and the AT rich
    loops. What this suggests to me is that in a thermal cycle the most often open or denatured areas
    would be those that are AT rich and the most often bonded areas would be those GC rich. Also if
    coding is more from the bubble areas then it would be more heavily AT.
    6. Salt levels can help or hinder denaturation. Thus if one could determine the temp. range of
    this h-bond world, then would could probably figure out the amount of salt. Or vice versa - if
    one knows the probable level of salt, one could suggest a reasonable temp range of denaturing
    or annealing variants. (Note the annealing temp needs to be about 25-30 C below the
    denaturation temp)
    7. Because polynucleotides tend to have a '3D structure that maximizes the contact of the highly
    soluble phosphate group with water and minimizes contact between bases and water', It would
    suggest that the obvious, that nucleotides were selected in a water environment. Yet it doesn't
    rule out that there was a dry part to this cycle.

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