On 7/22/2019 3:55 PM, smitra wrote:
This doesn't address the fundamental problems. People like Leslie
Orgel have explained why metabolism first is a non-starter.
And you think Nick Lane hasn't read Orgel?
He has argued on the basis of the difficulties of getting to
functional RNA, and more recently people like Paul Davies have pointed
out the fundamental nature of this problem. My suggestion is not some
new model, it simply makes conventional models such as e.g. the
protocell work better by putting these in a micro-environment that
itself has been forged in far from equilibrium conditions. The
micro-environments break the symmetry that can steer the chemistry
that takes place inside more coherently in one or the other direction
compared to whatever chemistry can go on in a macroscopic environment.
Keep in mind that the simplest functional living organism is likely
going to be similar to a microbe, involving hundreds of thousands of
different enzymes that are then all necessary to make each other and
maintain and copy the organism. There thus exists a massive gap from
simple chemistry to the simplest self-reproducing lifeforms. The only
plausible solution is then a scenario where simpler systems that would
not function good enough to be able to reproduce with a multiplication
factor of larger than one, can reproduce with a multiplication factor
larger than 1 in a protected environment.
Which Lane and others postulate to alkaline "white smokers".
Brent
But that environment must then have features that would have to play
the role of the more sophisticated molecular machinery that makes the
more advanced life forms work. Fixed features on the inner surface
area of a micro-environment can then work. The effect such features
have over the entire volume can be non-negligible in a small system.
Saibal
On 07-07-2019 08:32, 'Brent Meeker' via Everything List wrote:
I think Nick Lane's metabolism-first theory, which he discusses in his
book "The Vital Question", is more plausible. There's good online
talk by Lane https://www.youtube.com/watch?v=PhPrirmk8F4.
Brent
On 7/6/2019 8:32 AM, smitra wrote:
https://arxiv.org/abs/1711.01945
A followup article which focuses more on the mathematical issues is
under construction, the key points are:
1) In interstellar space, simple organic compounds captured in small
ice grains were subject to UV radiation and occasional heating due
to incident cosmic rays (CR). This induced a bond percolation
process that led to large clusters of organic molecules on a time
scale of $\gtrsim 10^6$ years.
2) On a proto-planet, such clusters can merge into loosely bound
superclusters. The deep interior of such superclusters can provide
for chemical micro-environments in which conventional models of
abiogenesis driven by cold-warm cycles can be considered.
3) Rapid fluctuations in the chemical potentials of certain chemical
compounds that can penetrate the supercluster, will be damped down.
Long term gradual and periodic changes then dominate, allowing any
biochemical systems inside the superclusters to more easily evolve
toward exploiting the conditions in their micro-environments,
compared to a similar system in the outside environment.
4) As the supercluster breaks up, the system experiences more of the
shorter term fluctuations that has more of a random character. The
system can then evolve to adapt to these fluctuations, when doing so
right from the start might not have worked.
5) On a small fraction of the superclusters these processes led to
microbes capable of surviving in the outside environment.
6) Microbes were transferred to Earth via a collision of a
microbe-containing proto-planet with the Moon. Fragments containing
microbes resulting from the giant impact rained down on the Earth.
Saibal
On 06-07-2019 10:48, 'Cosmin Visan' via Everything List wrote:
https://www.youtube.com/watch?v=r4sP1E1Jd_Y [1]
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[2].
Links:
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[1]
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