RNA observed forming on glass

[BH]

Hi.

I have read several articles on Google that RNA has been observed forming on basaltic glass . The scientists writing the professional articles and the journalists writing the popular science articles are theorizing that this happened during the Hadean Earth period. All the know materials needed were there then.


Also, I read in the comments section that RNA cannot reproduce without complex proteins. Someone else commented it has been observed to do so as a matter of fact.

I'm using my phone and it wont let me cut and paste links. But I was wondering what opinions you all may have if you have heard about this.

It is speculated that RNA formed on Mars billions of years ago too.

 

[bilby]

RNA replication can be catalysed by RNA; Proteins are not essential, but they do make things go a lot faster.

Which is important at this end of three and a half billion years of evolution, but probably wasn’t at the beginning of that process - after all, it’s not like the first life had much competition.

 

[Swammerdami]

The formation of molecular chains — polypeptides or nucleic acids — is accomplished with relative ease in the right environment. The key prerequisites for life's origin were containment — otherwise the complex molecules would quickly dissipate into the ocean — and free energy. The surface of glass might provide containment, but it is access to energy that is especially important. Huge amounts of energy were required for the huge amounts of growth and reproduction needed for evolution; and huge amounts of evolution were needed before complex energy engines like photosynthesis came into existence. (Many thinkers believe the early energy was provided by the acid-alkaline gradient present in the micropores of some underwater vents.)

One speculation is that an "RNA World" preceded the production of proteins, but perhaps more likely is that polypeptides and nucleic acids "cooperated" and boot-strapped increasing complexity. (Certainly the "invention" of the genetic code which links proteins to RNA was the amazing key that made complex life possible. Most of the "universal" genes are dedicated to implementing that code.) Another variation on an "RNA world" (with or without peptide catalysts?) is a soup of different types of nucleic acids. Those researchers found that a (proto-life) mixture of RNA, DNA and TNA was better able to replicate new nucleic acid chains that any pure nucleic acid would be

 

[lpetrich]

Assembly of RNA on volcanic glass? I don't think that that says much at all. It's possible to make proteins abiotically, though those proteins are essentially random ones, and the same seems to be true of RNA.

The big unanswered question is the origin of the RNA building blocks, the nucleotides. These are composed of a nucleobase, a ribose molecule, and a phosphate ion. It's possible to make nucleobases prebiotically, but it is much more difficult to make ribose prebiotically. The Butlerov formose reaction produces random sugars, complete with random asymmetries, and it is easily "poisoned".

In fact, the main criticism that I've seen of the RNA-world hypothesis is the difficulty of making RNA prebiotically. It's as if it's much easier to go from a RNA world to the present DNA-RNA-protein world.

 

[Swammerdami]

As lpetrich states, the 5-ring sugar ribose is hard to come by, at least randomly. Another difficulty is that each nucleotide needs a phosphate for the backbone, but phosphorus is relatively rare in sea water. Phosphorus is a key component of RNA, DNA, ADP, ATP and is the 5th-most common element in most living organisms, behind only the obvious C, N, O, H. (P is 6th-most common in vertebrates: they have much Calcium (#5) for bones and teeth.)

Yet phosphorus is just a trace element in sea water: Mg and Ca are several thousands of times more common. (I'm not sure about the oceans of the Hadean or Archean Era. This useful article has interesting results — I hope someone offers a report — and it does confirm that, with the earliest life just as now, Phosphorus was the critical element which limited total biomass.

To get around the alleged difficulty of RNA (or DNA) production, scientists have conjectured an earlier nucleic acid which served as a precursor to "RNA World" (or "RNA-Protein World"). Several alternative nucleic acids have been proposed, e.g. TNA which uses the 4-ring sugar threose, easier to produce than ribose. But TNA also has a phosphate backbone, so some go further and propose PNA —  Peptide_nucleic_acid#PNA_world_hypothesis, constructed easily without phosphate or sugar — as a possible predecessor to RNA.

In fact, a mash-up of various nucleic acids may have been the Goldilocks recipe for the early proto-life, as suggested by the link I gave in #3. The early genetic code would have started to evolve with these early nucleic acids, implying that that code may predate RNA.

 

[ramoss]

Hi.

I have read several articles on Google that RNA has been observed forming on basaltic glass . The scientists writing the professional articles and the journalists writing the popular science articles are theorizing that this happened during the Hadean Earth period. All the know materials needed were there then.


Also, I read in the comments section that RNA cannot reproduce without complex proteins. Someone else commented it has been observed to do so as a matter of fact.

I'm using my phone and it wont let me cut and paste links. But I was wondering what opinions you all may have if you have heard about this.

It is speculated that RNA formed on Mars billions of years ago too.

Well, self replicating RNA has been observed. When in the proper environment, these self replicating molecules do go through selective pressure, because 1) the rna does not perfectly replicate itself' and 2) Those rna molecules that reproduce faster and more efficiently out compete other forms of RNA that are not as effective.

Now, it's a long way from that to live, but the processes and principles that drive evolution in biological life can be observed in the much more primitive chemical reactions.