Sujet : Re: Ool - out at first base?
De : me22over7 (at) *nospam* gmail.com (MarkE)
Groupes : talk.originsDate : 19. Dec 2024, 05:49:09
Autres entêtes
Organisation : A noiseless patient Spider
Message-ID : <vk08k8$2ndnn$1@dont-email.me>
References : 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
User-Agent : Mozilla Thunderbird
On 19/12/2024 3:16 am, Mark Isaak wrote:
On 12/17/24 5:12 PM, MarkE wrote:
On 17/12/2024 6:33 am, Mark Isaak wrote:
What makes you think that you know enough about the universe to think that the problems you put forward will not likewise be obviated by further research?
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I don't, not with certainty. Hence I put forward possible OoL showstoppers for scrutiny.
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To that end, do you think the following recent examples have any merit at all? I'm not asking if you agree that they're a problem, rather, is there any legitimacy in addressing them as potentional problems for OoL?
- the tar paradox
Probably not a problem. It's easy to imagine mechanisms that could separate productive products from counterproductive ones.
- supply of concentrated nucleotides unbroken for millions of years
A problem, yes, but only in the sense that solving any puzzle is a problem. A showstarter (where research is the show), not a showstopper. Also, millions of years may be unnecessary. I suspect that one bottleneck of abiogenesis is for the proper conditions to come together, but once they do, a huge step could be taken in months, perhaps hours. I might be completely wrong about that, but then, others might be wrong about thinking optimum conditions must persist for millions of years.
It is difficult to quantify this time.
An estimate of the minimal length of RNA required for self-replication is 100 units:
"A true RNA replicase—a ribozyme capable of fully templating and polymerizing its own sequence—has not yet been discovered. Models suggest such a molecule would need to be at least ~100-200 nucleotides to fold into a structure complex enough to catalyze replication."
The assembly of such a long, complex polymer in the conditions present on the early earth is extremely difficult.
The problem is, it's not just the first naked RNA self-replicator (or autocatalytic set of self-replicating polymers) that solves the problem.
You then need to progress to a "primitive" protocell, which provides encapsulation. This is not capable of self-synthesis of activated nucleotides, therefore the environment is required to continue to supply these.
You then need to progress to an "advanced" protocell, which provides metabolism, including self-synthesis of activated nucleotides. Only then do you no longer require environmental life-support.
The combined probabilistic resources of X warm little ponds on Y planets are not relevant if no such geological/environmental conditions can be maintained for the time required. That needs to be demonstrated.
We could begin to gauge this experimentally by setting up simulated warm little ponds with wet/dry cycles, a steady supply of nucleotides, temerature variability, mechanical agitation, mineral substrates, pH changes, other checmicals, etc etc, and observe the development of RNA strands. I.e., something of an Miller-Urey experiment.
Wait...why has no-one done this? What better way to progress OoL research? "Look, our little warm ponds have produced a population of RNAs from 3 to 13 units long...this is the road to life!" The incentive is certainly there - peer accolades and grant funding would flow in.
Well, I can tell you why no-one is doing this and reporting the results*. Because we know that it will not produce growing RNA polymers. It will yield tar.
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* Damer and Deamer:
“[OoL research has] been mainly focused on individual solution chemistry experiments where they want to show polymerization over here, or they want to show metabolism over here, and Dave and I believe that it's time for the field to go from incremental progress to substantial progress. So, these are the four points we've come up with to make substantial progress in the origin of life, and the first one is to employ something called system chemistry, having sufficient complexity so instead of one experiment say about proteins, now you have an experiment about the encapsulation of proteins for example, and informational molecules built from nucleotides in an environment that would say be like an analog of the early Earth, build a complex experiment. Something we're calling sufficient complexity, and all of these experiments have to move the reactions away from equilibrium. And what do we mean by that? Well, in in your high school chemistry experiments, something starts foaming something changes color and then the experiment winds down and stops. Well, life didn't get started that way. Life got started by a continuous run-up of complexity and building upon in a sense nature as a ratchet. So we have to figure out how to build experiments that move will move away from equilibrium...”
“You can't sit in a laboratory just using glassware. You have to go to the field. You have to go to hot springs, you have to go to […] Iceland and come check and sit down and see what the natural environment is like, rather than being in the ethereal world of pure reactants and things like that...”
Source: A new model for the origin of life: A new model for the origin of life: Coupled phases and combinatorial selection in fluctuating hydrothermal pools.
https://youtu.be/nk_R55O24t4?feature=shared