Text 692, 68 rader
Skriven 2004-11-07 21:59:00 av Tinyurl.Com/uh3t (1:278/230)
Ärende: Re: No Grace Period for M
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(I posted this 9 days ago, via Google Groups while I was away from my
usual method of posting, but it never appeared, so I'm trying to post
it again, this time by my usual method:)
> From: tomhendricks474@cs.com (TomHendricks474)

Background: In essence, metabolism is nothing more than utilizing
the free energy of meta-stable chemical systems to do useful work
such as replicating. A single molecule can be in a meta-stable state,
able to decay to a lower energy level except it must cross a barrier.
Two molecules with different charge or redox potential can react to
neutralize each other, but there's a barrier to immediate spontaneous
reaction. Normally either would sit around waiting for random thermal
energy fluctions, or quantum tunneling, to allow the barrier to be
crossed. But a catalyst can enable a more immediate crossing of the
barrier. Some catalysts can also extract energy from this crossing,
and apply that energy to drive some useful action, hence metabolism.

> Some scenarios suggest that first came a first
> replicator - then followed a grace period where
> natural selection allowed this first replicator to
> develop a metabolism system to power itself!

I'm not aware of any such proposed scenerio. Please cite a few,
show where somebody posted such a proposal on the net.

In the pre-life time, there were probably lots of activated
chemicals caused by UV radiation and geothermal vents, including
lots of meta-stable chemicals and combinations of chemicals.
Per the abiogenesis scenerios I've usually proposed, various
spontaneous reactions occurred, resulting in lots of different
chemical species as byproducts, and by chance some of these
chemicals have catalytic capability. The first replicator may
have been nothing more than a catalytic loop. For example, if
A[i] are abundant meta-stable chemicals or combinations of chemicals,
C[i] are catalysts, and E[i] are end products of the catalyzed
reactions, we might have something like:
 A1a + A1b --(C1)-> C2 + E1
 A2a + A2b --(C2)-> C3 + E2
 A3a + A3b --(C3)-> C1 + E3
then C1 -> C2 -> C3 -> C1 is the catalytic cycle I speak of.
As soon as one molecule of C1 exists, it catalyzes the creation
of several molecules of C2, which catalyze the creation of many
molecules of C3, which catalyze the creation of very many molecules
of C1, and the cycle rapidly converts as much of A1a...A3b as available.

So do you have any proof the first replicator couldn't have been that
simple?

> how is it that that first replicator was in no way
> harmed or destroyed by the environment.

No such argument is needed under my scenerio. The catalytic cycle
makes very large amounts of itself, consuming readily-available
chemicals, using the free energy available in some of those chemicals.
Of course every so often one such molecule is damaged or destroyed,
but there are many other copies of the same molecular species to
replace it, so once the catalytic cycle is established, and so long
as the input chemicals A[i] are abundantly available, the catalytic
cycle persists.
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