My discussion about life as an energy moderator has mostly
been about amino acids, protein, RNA etc. But there may
be clues about the origin, in membranes:
"many of the most basic cellular processes, including cell movement, cell growth, cell division,
formation of intercellular junctions, secretion, and endocytosis, depend on the movement of membrane
components and would probably not be possible if membranes were rigid, nonfluid structures."
But for cells to be fluid the temperature must be high and above the transition temperature,
"If the temp is slowly lowered, a point is reached where a distinct change in the nature of the
bilayer occurs. The lipid is converted from its normal liquidlike state to a 'frozen' crystalline
gel in which the movement of the phosphlipids is greatly restricted. The temperature at which this
change occurs is called the transition temp."
But just being fluid in high temp, may not be the complete answer, or be the most selected membrane,
"Membrane fluidity seems to provide a perfect compromise between a rigid, ordered structure in
which mobility would be absent and a completely fluid, nonviscous liquid in which the components of
the membrane could not be oriented and the opportunity for organization and mechanical support
would be lacking."
So what does all this suggest? I think here too we have proof of the membrane as being a novel form
of energy moderation - and the membrane is responding to a heat cycle, and being selected within a
heat cycle.
For the membrane to be fluid, it has to be hot and above the transition temp. But sometimes being
nonfluid is advantageous and that happens below the transition temp. Therefore a cycle that crossed
that line may be the one that is selected.
Also note that the transition temp is variable due to the type of fatty acid and can seem to range
from 0-60C.
I think that because the transition temp at its highest of 60C is still lower than that of
nucleotides separating completely, we have a clue to the origin.
Couple this with the fact of a cooling earth and we have this reasonable possibility.
Early earth had a hotter heat cycle that effected the selection of nucleotides, later earth had a
cooler heat cycle that effect the selection of membranes. This is clear due to the lower transition
temperature levels. Quotes from 'Cell and Mole Bio', Karp.
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