How could life originate near deep sea vents?

[SLD]

It seems to me that the idea of life originating near deep sea vents is very problematic. Peptide chains could not form in such an aquatic environment. They need to have the drying and resetting cycle of tides or waves to form the long chains.

Or is there another way near boiling water that they could form?

SLD

 

[repoman]

There is a thread here and I think lpetrich had some input.

this one

https://talkfreethought.org/showthread.php?10999-Seven-planets-orbiting-a-star

 

[Thomas II]

It seems to me that the idea of life originating near deep sea vents is very problematic. Peptide chains could not form in such an aquatic environment. They need to have the drying and resetting cycle of tides or waves to form the long chains.

Or is there another way near boiling water that they could form?

SLD

http://www.whoi.edu/news-release/study-tests-theory-that-life-originated-at-deep-sea-vents

 

[fromderinside]

Very deep. Very very black.*


* ^{_{We were trolling along and got hooked on the articles.}}

 

[J842P]

It seems to me that the idea of life originating near deep sea vents is very problematic. Peptide chains could not form in such an aquatic environment. They need to have the drying and resetting cycle of tides or waves to form the long chains.

Or is there another way near boiling water that they could form?

SLD

Well, for starters, using peptides as a basic biopolymer probably came *after* the origin of life. Indeed, while all extant life makes heavy, heavy use of peptides/proteins, and indeed, almost certainly the LUCA (last-universal-common ancestor) did protein translation, there is good reason to believe that there was an "RNA world" that predated this, where RNA acted as the fundamental catalytic molecule. Indeed, if we look at the molecule that does the actual translation/protein-synthesis, the peptide portion is the structural unit, while the catalytic unit is the rRNA!

http://science.sciencemag.org/content/289/5481/878

 

[SLD]

It seems to me that the idea of life originating near deep sea vents is very problematic. Peptide chains could not form in such an aquatic environment. They need to have the drying and resetting cycle of tides or waves to form the long chains.

Or is there another way near boiling water that they could form?

SLD

Well, for starters, using peptides as a basic biopolymer probably came *after* the origin of life. Indeed, while all extant life makes heavy, heavy use of peptides/proteins, and indeed, almost certainly the LUCA (last-universal-common ancestor) did protein translation, there is good reason to believe that there was an "RNA world" that predated this, where RNA acted as the fundamental catalytic molecule. Indeed, if we look at the molecule that does the actual translation/protein-synthesis, the peptide portion is the structural unit, while the catalytic unit is the rRNA!

http://science.sciencemag.org/content/289/5481/878

I think you're confusing polypeptides with DNA. The very definition of life implies the need for polypeptides. Proteins are what make life work. The RNA world did precede the DNA one, but that's because RNA and DNA both code for long polypeptides chains.

SLD

 

[Peez]

Well, for starters, using peptides as a basic biopolymer probably came *after* the origin of life. Indeed, while all extant life makes heavy, heavy use of peptides/proteins, and indeed, almost certainly the LUCA (last-universal-common ancestor) did protein translation, there is good reason to believe that there was an "RNA world" that predated this, where RNA acted as the fundamental catalytic molecule. Indeed, if we look at the molecule that does the actual translation/protein-synthesis, the peptide portion is the structural unit, while the catalytic unit is the rRNA!

http://science.sciencemag.org/content/289/5481/878

I think you're confusing polypeptides with DNA. The very definition of life implies the need for polypeptides. Proteins are what make life work. The RNA world did precede the DNA one, but that's because RNA and DNA both code for long polypeptides chains.

SLD

Not exclusively, and probably not always. According to the RNA world hypothesis, RNA acted as hereditary molecules as well as catalyst, no peptides required. The very first line in Wikipedia's article on the topic: "The RNA world is a hypothetical phase of the evolutionary history of life on Earth, in which self-replicating RNA molecules proliferated before the evolution of DNA and proteins."

Peez

 

[J842P]

Well, for starters, using peptides as a basic biopolymer probably came *after* the origin of life. Indeed, while all extant life makes heavy, heavy use of peptides/proteins, and indeed, almost certainly the LUCA (last-universal-common ancestor) did protein translation, there is good reason to believe that there was an "RNA world" that predated this, where RNA acted as the fundamental catalytic molecule. Indeed, if we look at the molecule that does the actual translation/protein-synthesis, the peptide portion is the structural unit, while the catalytic unit is the rRNA!

http://science.sciencemag.org/content/289/5481/878

I think you're confusing polypeptides with DNA. The very definition of life implies the need for polypeptides. Proteins are what make life work. The RNA world did precede the DNA one, but that's because RNA and DNA both code for long polypeptides chains.

SLD

No, I'm pretty sure I'm not confused. In extant lifeforms, genetic replications/storage is based on nucleic acids, whereas catalytic functions are performed by polypeptides/proteins. The RNA-world hypothesis is that *before this* there was a time when both of these functions were performed by RNA, and there was no DNA/proteins.

 

[Sarpedon]

The bit about no DNA/proteins is what's wrong.

No DNA yes. No proteins, no.

The idea is that the basic amino acids were formed by natural processes first. That they can be has been proven.

Then proteins were formed on a matrix of crystals formed around the vents. This is Gunter Wachterhauser's theory which is widely accepted today. Self replication of proteins then developed, and from there, the more complex molecules formed, and with them cells, nucleic acids RNA and DNA. Once cell membranes are formed (probably prior to either DNA or RNA) the early cells could be independent from the vents and their crystal matrices. (Simple) Proteins come very early in the process

 

[Peez]

The bit about no DNA/proteins is what's wrong.

No DNA yes. No proteins, no.

The idea is that the basic amino acids were formed by natural processes first. That they can be has been proven.

Then proteins were formed on a matrix of crystals formed around the vents. This is Gunter Wachterhauser's theory which is widely accepted today. Self replication of proteins then developed, and from there, the more complex molecules formed, and with them cells, nucleic acids RNA and DNA. Once cell membranes are formed (probably prior to either DNA or RNA) the early cells could be independent from the vents and their crystal matrices. (Simple) Proteins come very early in the process

That is one hypothesis.

Peez

 

[J842P]

The bit about no DNA/proteins is what's wrong.

No DNA yes. No proteins, no.

The idea is that the basic amino acids were formed by natural processes first. That they can be has been proven.

Then proteins were formed on a matrix of crystals formed around the vents. This is Gunter Wachterhauser's theory which is widely accepted today. Self replication of proteins then developed, and from there, the more complex molecules formed, and with them cells, nucleic acids RNA and DNA. Once cell membranes are formed (probably prior to either DNA or RNA) the early cells could be independent from the vents and their crystal matrices. (Simple) Proteins come very early in the process

These are all competing views of how early life would have formed. There is no widely-accepted (in the sense that it is thought to be a correct account rather than merely a plausible one) of the origins of life. One view exists, let's call it the Strong RNA World hypothesis, that posits that it was *all RNA* which mean no-proteins. People who advocate this position generally point to evidence like the paper I originally posted which shows that the most primitive cellular machinery (primitive as in phylogenetically basal) are actually ribozymes. Gunter Wachterhauser's theory is a form of "metabolism-first" hypotheses.

 

[Sarpedon]

Please forgive me, I guess I didn't know enough about the RNA world hypothesis to comment.

Its an interesting theory, does anyone have any idea what the pre-protein Ribosome would have looked like?

 

[Peez]

Please forgive me, I guess I didn't know enough about the RNA world hypothesis to comment.

Its an interesting theory, does anyone have any idea what the pre-protein Ribosome would have looked like?

Under the "RNA world" hypothesis the precurser to a ribosome would have been a ribozyme.

Peez

 

[SLD]

I think you're confusing polypeptides with DNA. The very definition of life implies the need for polypeptides. Proteins are what make life work. The RNA world did precede the DNA one, but that's because RNA and DNA both code for long polypeptides chains.

SLD

Not exclusively, and probably not always. According to the RNA world hypothesis, RNA acted as hereditary molecules as well as catalyst, no peptides required. The very first line in Wikipedia's article on the topic: "The RNA world is a hypothetical phase of the evolutionary history of life on Earth, in which self-replicating RNA molecules proliferated before the evolution of DNA and proteins."

Peez

OK. I read that article, and you are correct, RNA ribozymes could have acted as catalysts in a form of life. But I remain a bit skeptical that one can have life without proteins. RNA codes for proteins as much as does DNA. Ribosomes are RNA building proteins. The. Article in Wikipedia does provide for a co-evolution of RNA and proteins. That makes more sense to me.

SLD

 

[Sarpedon]

I still find the metabolism first theory to be more logical, as it goes from simple things that can be produced through non-metabolism, but the RNA ribozyme theory doesn't necessarily imply that the early ribozymes are the same as today. It seems to imply that they were simpler structures that self replicated. Evolution would have produced ones that not only self replicated, but also created an environment that helped their self replication (ie, by producing other proteins, perhaps). While plausible, I don't find it as compelling as the other theory, which provides not only a how but also a where.

 

[Peez]

Not exclusively, and probably not always. According to the RNA world hypothesis, RNA acted as hereditary molecules as well as catalyst, no peptides required. The very first line in Wikipedia's article on the topic: "The RNA world is a hypothetical phase of the evolutionary history of life on Earth, in which self-replicating RNA molecules proliferated before the evolution of DNA and proteins."

Peez

OK. I read that article, and you are correct, RNA ribozymes could have acted as catalysts in a form of life. But I remain a bit skeptical that one can have life without proteins. RNA codes for proteins as much as does DNA. Ribosomes are RNA building proteins. The. Article in Wikipedia does provide for a co-evolution of RNA and proteins. That makes more sense to me.

SLD

Indeed proteins play such integral roles in the living systems we know that it is hard to imagine life without them. Of course we are getting into the fuzzy edge of the definition of "life", but I can imagine self-replicating RNA molecules evolving and incorporating amino acids, polypeptides, and proteins, and eventually evolving to depend on them.

Peez

 

[Peez]

I still find the metabolism first theory to be more logical, as it goes from simple things that can be produced through non-metabolism, but the RNA ribozyme theory doesn't necessarily imply that the early ribozymes are the same as today. It seems to imply that they were simpler structures that self replicated. Evolution would have produced ones that not only self replicated, but also created an environment that helped their self replication (ie, by producing other proteins, perhaps). While plausible, I don't find it as compelling as the other theory, which provides not only a how but also a where.

It is also possible that robozymes and simple metabolism evolved separately and later merged. We might never know, but these are interesting issues.

Peez