Re: Nature via Nurture: What makes you who you are.

From: Phil Osborn (philosborn2001@yahoo.com)
Date: Sat May 31 2003 - 16:27:08 MDT

  • Next message: Michael M. Butler: "[MED] Guinea Pig Auditory Cells Regenerated"

    I'm trying to recall when Koestler started writing
    about the differentiation of cells from egg to adult
    and the subsequent de-differentiation of aging. His
    analogy was of a typewriter keyboard in which a lot of
    the keys were taped over, but with time the tape fell
    off.

    That IS the interesting question:

    >From: Brett Paatsch (paatschb@optusnet.com.au)
    Date: Fri May 30 2003 - 21:58:23 MDT

    (Aside: It seems to me that the popular fixation on
    DNA seems to be wrong to me. Its DNA *interacting*
    with proteins which do almost everything that matters
    in biology. DNA of itself is almost completely
    uninteresting. The same DNA is in every cell
    type. Yet what makes different cell types and this
    applies all the way back to the fertilized egg which
    contains a cocktail of proteins is the way the
    proteins interact with the DNA and selectively turn
    certain genes off and on in turn creating other
    proteins in the mix both in type and in number. If we
    knew all the proteins in the maternal oocyte, both
    number and type, that would be powerful knowledge
    indeed, because these early proteins are crucial to
    early development and they do not come from the DNA of
    the fertilized egg or new individual but from the
    mother. At this point we don't know what these are).
    >

    So, there is a kind of meta-DNA cellular memory? With
    error checking, one might presume? And the ability to
    respond to changes? Can we come up with an overall
    description or characterization of this meta-system?

    I continue to be intrigued with the fact that about
    99% of the human DNA is considered "junk." So, if it
    is "junk", then it could presumeably be deleted?
    Right? How hard would it be to test this with some
    organism with a lot of "junk" DNA but a small enough
    total to make it practical to actually clean out a
    large proportion of the "junk" and then see if the
    system still works.

    Might there not be significant advantages in deleting
    that 99%, assuming that only the 1% is in fact useful?
     A lot of the 99% is probably old viral garbage, I
    hazard. Perhaps some of it is actually used by the
    cell for blocking viral reproduction in some way, so
    that we wouldn't discover the use until it mattered?
    Perhaps, on the other hand, viruses have learned to
    use some of the "junk," like common subroutines or old
    .dll's that the OS never uses until you happen to
    bring in some old program. Removing it might disable
    those viruses.

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