If anyone is interested in further reading on this topic, or on evolution/origin of life in general, I highly recommend "The Logic of Chance" by Eugene Koonin. The book pieces together the latest knowledge from all the major fields of biology (genetics/bioinformatics, structural/physics, etc), math, physics, and philosophy in a way I've never seen done before. It interrogates virtually every hypothesis of the origin…
The RNA World Hypothesis
11–20 of 44 posts
Re: The RNA World Hypothesis
#12If anyone is interested in further reading on this topic, or on evolution/origin of life in general, I highly recommend "The Logic of Chance" by Eugene Koonin. The book pieces together the latest knowledge from all the major fields of biology (genetics/bioinformatics, structural/physics, etc), math, physics, and philosophy in a way I've never seen done before. It interrogates virtually every hypothesis of the origin…
looks like a good book. i wish it wasn't so expensive on amazon
Re: The RNA World Hypothesis
#13If anyone is interested in further reading on this topic, or on evolution/origin of life in general, I highly recommend "The Logic of Chance" by Eugene Koonin. The book pieces together the latest knowledge from all the major fields of biology (genetics/bioinformatics, structural/physics, etc), math, physics, and philosophy in a way I've never seen done before. It interrogates virtually every hypothesis of the origin…
All the popular presentations about the "RNA world" are either incomplete and/or logically inconsistent.
There certainly was a RNA world, in the sense of a world where there was no DNA, but only RNA.
However, there must have existed 2 stages of the RNA world, the later stage, when protein synthesis based on translation from RNA existed, like today, and also an earlier stage, when only RNA replication existed, but RNA did not perform any useful function for its host living being, but it was only a virus that was replicated using energy and molecular components from its host.
The fact that there are RNA molecules that can have a catalytic effect like enzymes, as mentioned in the article is completely irrelevant. If such catalytic RNA molecules had ever existed before the apparition of RNA replication, they would have immediately disappeared without living any descendants.
Only from the moment when some self-replicating RNA molecules has appeared, i.e. the first virus, we have some chain of nucleic acid replications, which has continued until today and all the existing nucleic acid molecules must be descendants of the first virus.
The first replicating RNA molecule required for its synthesis energy and molecular components, in the form of ATP and free nucleotides, which can condense into RNA.
So there must have already existed an equivalent of a bacteria, with metabolism using energy from the environment (i.e. dihydrogen with carbon dioxide and ionic gradients), which was already able to make ATP, which would have been needed to synthesize the polymers made by condensation, e.g. peptides. The apparition of the first RNA virus was an initially undesirable side-effect of using ATP to perform polymer condensations.
Because any memory molecule, like RNA, needs an already existing living being for its first replication, there must have been a stage prior to the RNA world, when there were self-replicating living beings, but without memory molecules.
The self-replication of a system does not need a memory, it can be "hard-wired", where there is a closed chain of chemical reactions where each reaction synthesizes a new component based on previous components and eventually the first component is synthesized from the last components.
However such a self-replicating system without a memory had extremely low chances of evolution, because any random change was almost certain to break the self-replication cycle, leading to death without descendants.
Only after the apparition of RNA, and especially after the later appearance of the RNA to protein translation mechanism, it became possible for mutations to accumulate and eventually create a variety of living beings.
While the first RNA must have been a virus, because diverting ATP and other useful internal components to the production of RNA molecules could not have been of any good for the host, some time after the apparition of RNA-based protein synthesis, some form of symbiosis between a host and some DNA virus must have created the ancestors of bacteria.
Re: The RNA World Hypothesis
#14If anyone is interested in further reading on this topic, or on evolution/origin of life in general, I highly recommend "The Logic of Chance" by Eugene Koonin. The book pieces together the latest knowledge from all the major fields of biology (genetics/bioinformatics, structural/physics, etc), math, physics, and philosophy in a way I've never seen done before. It interrogates virtually every hypothesis of the origin…
About virology, there is no doubt that the first RNA molecule was a virus. All the popular presentations about the "RNA world" are either incomplete and/or logically inconsistent. There certainly was a RNA world, in the sense of a world where there was no DNA, but only RNA. However, there must have existed 2 stages of the RNA world, the later stage, when protein synthesis based on translation from RNA existed, like t…
No, you're not postulating an RNA world here. The whole point of the RNA world (aka "RNA first") hypothesis is that the first life (self-contained, self-replicating particles) was RNA-based, and both proteins and lipid bilayers came later. If you argue that the first RNA was a virus that parasitized already existing organisms, then it's usually called a "metabolism first" hypothesis.
Re: The RNA World Hypothesis
#15If anyone is interested in further reading on this topic, or on evolution/origin of life in general, I highly recommend "The Logic of Chance" by Eugene Koonin. The book pieces together the latest knowledge from all the major fields of biology (genetics/bioinformatics, structural/physics, etc), math, physics, and philosophy in a way I've never seen done before. It interrogates virtually every hypothesis of the origin…
Re: The RNA World Hypothesis
#16Also anyone who’s worked in a lab trying to keep some Lb plates sterile would immediately see how difficult it would be to keep an earth sized Lb plate sterile if the galaxy has a ton of life harboring planets.
Re: The RNA World Hypothesis
#17Earlier quoted context omitted.
About virology, there is no doubt that the first RNA molecule was a virus. All the popular presentations about the "RNA world" are either incomplete and/or logically inconsistent. There certainly was a RNA world, in the sense of a world where there was no DNA, but only RNA. However, there must have existed 2 stages of the RNA world, the later stage, when protein synthesis based on translation from RNA existed, like t…
> So there must have already existed an equivalent of a bacteria, with metabolism using energy from the environment (i.e. dihydrogen with carbon dioxide and ionic gradients), which was already able to make ATP, which would have been needed to synthesize the polymers made by condensation, e.g. peptides. The apparition of the first RNA virus was an initially undesirable side-effect of using ATP to perform polymer conde…
While there was replicating RNA before any DNA and before any proteins made by translation from RNA, metabolism must have existed before any RNA and catalysis must have been done with peptides produced by other ways than translation from RNA (today there still are such non-ribosomal peptides).
Speaking about a RNA world is correct only in this sense, because RNA could not have performed any function before a mechanism for its replication had appeared and such a mechanism could not appear in any environment where ATP and the other nucleotides did not already exist.
ATP and the other nucleotides could not be made without an already functioning metabolism.
On the other hand, there is absolutely no need of RNA or of any other memory molecule for a working metabolism.
These precedence relations are as certain as 2 + 2 = 4, so speaking of any other kind of RNA world is senseless, despite the fact that there have been indeed many publications that fail to mention why the appearance of RNA before ATP and before metabolism is impossible.
Re: The RNA World Hypothesis
#18I have no doubt that our life originally evolved from an RNA world. I’m just not convinced the world is earth. This shit could not have happened so fast (few tens or hundreds of million years?) the moment it became conducive on earth. It must have flown in as archea from elsewhere! Also anyone who’s worked in a lab trying to keep some Lb plates sterile would immediately see how difficult it would be to keep an earth…
Unless you worked in an enormous vaccuum, I'm not realy sure how that's supposed to be comparable.
Re: The RNA World Hypothesis
#19“I have no doubt that life emerged from an RNA first world”
and
“I have no doubt that life emerged from a metabolism first world”
Last I checked, nobody should have absolute certainty for how life began. Progress comes from skepticism. Have more doubt!
Re: The RNA World Hypothesis
#20Earlier quoted context omitted.
How is it simultaneously possible to be a personal friend to someone and not have had the opportunity to interact with that person?
Sorry - run on sentences made it unclear. My mentor is the friend. I'm the one that's never interacted