So to recap:
-- RNA monomers can arise by purely chemical means
-- RNA can either self-polymerize or use clays, etc as catalysts
-- RNA selectively enters rudimentary micelles as a monomer but not escape as a polymer
-- Micelles/vesicles "compete" with each other based on their ability to concentrate monomers/creat polymers
-- RNA enzymes (ribozymes) can function both as polymerization catalysts
and as a selective advantage
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EDIT: I forgot to point out that extant metabolic pathways and cellular machinery bear the hallmarks of an RNA-based origin. This has been observed since at least the 1970s (J Mol Evol 1976). Numerous cofactors (acetyl-CoA, vitamin B12, etc) use nucleotides as the indispensible "handle" and the ribosome's catalytic sites are RNA-based, not protein-based. The protein components of ribosomes are obvious add-ons that function to stabilize the superstructure; they're not the fundamental heart of it.
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That's a portfolio of proven biochemistry upon which natural selection can act. No DNA necessary. No protein necessary.
Thanks for taking the time to respond - apologies that I haven't been able to reply sooner.
This is a good description of life IMO:
http://www.nasa.gov/vision/universe/starsgalaxies/life's_working_definition.html
http://www.nasa.gov/vision/universe/starsgalaxies/life's_working_definition.html
"
Living things tend to be complex and highly organized. They have the ability to take in energy from the environment and transform it for growth and reproduction. Organisms tend toward homeostasis: an equilibrium of parameters that define their internal environment. Living creatures respond, and their stimulation fosters a reaction-like motion, recoil, and in advanced forms, learning. Life is reproductive, as some kind of copying is needed for evolution to take hold through a population's mutation and natural selection. To grow and develop, living creatures need foremost to be consumers, since growth includes changing biomass, creating new individuals, and the shedding of waste."
As for the gray areas like RNA viruses I don't consider them living (my opinion only) because they have no cells and they may only reproduce by invading a host cell (typically with very bad results)
Some notes to the articles you linked:
1. "researchers have been able to show RNA could've arisen by purely chemical means (
Nature 2009),"
I would disagree that any researcher has been able to show this, as no test or experiment has been successful in demonstrating this. So it's purely speculative. From the article you linked:
"At some stage in the origin of life, an informational polymer must have arisen by purely chemical means. According to one version of the ‘RNA world’ hypothesis, this polymer was RNA, but attempts to provide experimental support for this have failed."
From Professor Robert Shapiro, Professor Emeritus of Chemistry at NYU:
"...
the probability of a self-replicating RNA molecule randomly assembling from a pool of chemical building blocks is so vanishingly small that its happening even once anywhere in the visible universe would count as a piece of exceptional good luck." - Scientific American "A Simpler Origin of Life" June 2007 p.48
2. "that activated RNA could self-polymerize on abiotic substrates such as clays (
JACS 2006),"
The chemistry here is out of my league.
![[winking]](http://l.yimg.com/j/assets/img/emoticons/classic/wink.r191677.gif "Winking [winking]")
I couldn't access the latter part of the article that discussed the significance to origins and early evolution. The major hurdle here would be how did the incredibly complex RNA develop and survive prebiotic conditions in the first place:
"
Cells and nucleic acid represent high-technology devices that are extremely unlikely to have formed by chance - and consequently must have been constructed by an evolutionary process based on existing lifeforms."
http://originoflife.net/crystals/
3. RNA can actually
self-polymerize without catalytic enzymes (
JACS 2014)
"No one has been able to synthesize RNA without the help of protein catalysts or nucleic acid templates, and on top of this problem, there is the fragility of the RNA molecule to contend with."
http://www.nasa.gov/vision/universe/starsgalaxies/life's_working_definition.html
And from the article you linked:
"However, despite recent advances in autocatalytic RNA synthesis and ribozyme-catalyzed RNA-dependent RNA polymerization, no self-
replicating nucleic acid system capable of open-ended evolution has yet been developed."
4. RNA can function as an enzyme (this won the
1989 Nobel in chemistry),
In this case it is shown that RNA can function as a biocatalyst or enzyme
in a living cell.
Further from from Carol Cleland in the NASA article:
It seems to me that all theories of the origin of life face two major hurdles. The biggest one is explaining the origin of the complex cooperative schema worked out between proteins and nucleic acids -- the controlled production of self-replicating catalytic systems of biomolecules. All of the popular accounts of the origin of life strike me as side stepping this issue. Instead, they focus on the other hurdle: producing amino acids and nucleotides, and getting them to polymerize into proteins and nucleic acids (typically, RNA). But it seems to me that none of them have provided us with a very satisfying story about how this happened.
All the scenarios that have been proposed for producing RNA under plausible natural conditions lack experimental demonstration, and this includes the RNA world, clay crystals, and vesicle accounts..."
What can currently be proven and demonstrated in the field of biology, biochemistry etc. is that life always comes from preexisting life, cells come from preexisting cells etc.
