On 7/26/2019 4:13 PM, smitra wrote:
On 27-07-2019 00:39, 'Brent Meeker' via Everything List wrote:
On 7/26/2019 3:07 PM, smitra wrote:
On 23-07-2019 21:26, 'Brent Meeker' via Everything List wrote:
On 7/23/2019 12:07 PM, smitra wrote:
On 23-07-2019 04:10, 'Brent Meeker' via Everything List wrote:
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?
Orgel's original arguments can be generalized into a no-go
argument that precludes all existing biochemical models for
abiogenesis. This has been pointed out by Paul Davies. However,
Davies then argues that this means that the problem lies with the
fundamental laws of physics, but one can also circumvent the
problems raised by sticking to ordinary physics and getting to the
right structures within which the conventional models can work.
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".
This is impossible, because you need to build structures on the
molecular scale without the enzymes that living organisms have
available. Local thermal equilibrium won't allow chemical
reactions to proceed differently a few atoms distance away at one
site of a large molecule compared to another. So, one needs to
consider processes in an environment where local thermal
equilibrium will be violated on a molecular scale. This can happen
in a cryogenic environment in space where UV radiation creates
radical and ions and occasional cosmic ray interaction causes
heating allowing nearby ions and radicals to form bonds. Such
processes have been studied with the ail of getting to the
fundamental building blocks of life, but that doesn't really work
because of the random nature of the products.
But under those conditions one will also get extremely large
clusters of organics, and they can serve as the housing within
which one can have the right structures for conventional models to
work. Confinement in a small volume is essential as there will be
as small number of structures inside each such system. This means
that the net effect of all the structures inside any particular
system will differ due to statistical fluctuations. In a larger
volume, the average effects of the structures would average out to
some mean effect, also the effect the structures on the surface
have on the chemistry taking place in the entire volume would be
less the larger the volume becomes.
Which is why the huge surface area and fractal-like compartments of
white-smokers are needed for the origin of life:
http://hoffman.cm.utexas.edu/courses/hydrothermal_vents.pdf
I direct your attention to Box 3.
Brent
You can't get such structures down to the molecular scale there.
Catalyzing a reaction on a surface is at molecular scale.
Yes, but in a trivial sense as the surfaces are smooth on the
molecular scale. You can, of course, get many interesting chemical
reactions in such conditions, but there is no way you can build
molecular machines that have specially crafted molecules as their
parts this way that are then able to make their own parts or the parts
of other machines. You're starting from a situation where the massive
amount of information needed to specify how all the machines in the
end product (a living organism) doesn't exist, and it won't therefore
come into existence by virtue of having realized a number of
biochemical processes.
You are ignoring the point of the abiogensis from the metabolism first
view. The reactions are thermodynamically favored and don't require
specific proteins to catalyze them.
Brent
Saibal
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