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Just out of curiosity, i've never heard of PNAs as progenitor molecules... any good papers on the subject? Graft
I read it in Scientific American quite some time back, and it stuck in my head. Searching... here, I think this is the one:
The issue itself is filed away somewhere in a box that will take me a lot of work to dig out, so unless you don't have access to a local copy I'd prefer not to. The article might have a reference to a better paper than a scientific american article, hopefully. Bryan
Wow! Great stuff! Thanx for an article that broadens my universe!
I was immediately inspired to revise my family tree. There are now 3 nodes at the root: The PNA World, The RNA World, and Biota (or should it be Eubiota?) The first two items are flagged "hypothetical", "extinct" and "supposed precursors of all Biota".
Critiques: The technicalities are simply too overwhelming for the general reader. I won't comprehend the structure in the 1st paragraph without a diagram. Shouldn't it be a goal to present all molecular structures both as diagrammed formulas and as objects rotating in a reader-controlled panorama? (The technology exists, I think, but the work here is daunting.)
The 1st sentence in the 2nd paragraph is fine, but the rest of this 'graph is incomprehensible to a general reader (the sin of unexplained jargon). Wouldn't it be enough, comparing reactivity and stability, to say, for example, that double helix DNA comes apart at temperatures 20 Celsius lower than double chain PNA?
Are there such things as PNA catalysts (analogous to enzymes and ribozymes)? This would be of great significance for evolution.
If the PNA and RNA Worlds existed simultaneously, it is clear that PNA's lower reactivity and greater stability would allow the RNA World to gobble it up.
Could one say [gasp:anthropomorphic] that RNA still rules today, using DNA as a convenient, slowly mutating, copyable information store? If there were CPUs in the cell, would they be ribozymes? I see the ribosomes and some of the other things as distributed processors.
Solo Owl 01:42 Nov 4, 2002 (UTC)
It is true that some researchers have proposed that PNAs were progenitor molecules, but I don't think anyone actually takes that claim seriously. There is absolutely no evidence that PNAs ever existed outside of the lab, unlike RNA for which many natural ribozymes are known.
the addition of that part is unnecessary to the lead sentence. PNA does not exists in nature. Full stop. Why add the qualifier "present life"? With the same reasoning, endless strings of qualifiers may be added: in present life, nor on Venus, Mars, the moon Europe, nor in the past, but maybe in the future ......... Let's stick to the facts and do not load a simple sentence with wishful thinking, OR and POV. Northfox ( talk) 11:12, 6 February 2008 (UTC)
Northfox ( talk) 04:14, 7 February 2008 (UTC)
unindent. From the same lead aricle: "The lead should not "tease" the reader by hinting at but not explaining important facts that will appear later in the article." The fragment 'not known in modern life' hints that it was part of the biosphere in pre-modern life (whatever that you imagine that to be). Fact is that PNA is not part of life as we know it. And we don't know any other life forms. So we can only speculate about it. And we do so in the related paragraph furthe below. PNA is notable for very real medical (and related) research, not for a hypothetical precursor of RNA or DNA. Northfox ( talk) 11:35, 12 February 2008 (UTC)
I took the liberty to change the lead sentence. Biggest reason was that the 'but' makes the wrong connection. In the previous version, it modified 'modern life forms', but logically it should modify the 'occur naturally', by contrasting it to 'artificially synthesized'. Since User:ScienceApologist kept reverting me, I chose a different, more logical, order of statements. Also, "polymer" is better than "compound". Northfox ( talk) 08:23, 17 February 2008 (UTC)
quick addendum: we need to define 'modern life forms' here. There is no 'modern life' wikiarticle. Anybody with a good outside link? Northfox ( talk) 08:26, 17 February 2008 (UTC)
http://www.sciencedaily.com/releases/2012/11/121110093550.htm — Preceding unsigned comment added by Jjknack1 ( talk • contribs) 22:24, 11 November 2012 (UTC)
![]() | This article is rated Start-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | ||||||||||||||||||||||||||||||||||||||||
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Just out of curiosity, i've never heard of PNAs as progenitor molecules... any good papers on the subject? Graft
I read it in Scientific American quite some time back, and it stuck in my head. Searching... here, I think this is the one:
The issue itself is filed away somewhere in a box that will take me a lot of work to dig out, so unless you don't have access to a local copy I'd prefer not to. The article might have a reference to a better paper than a scientific american article, hopefully. Bryan
Wow! Great stuff! Thanx for an article that broadens my universe!
I was immediately inspired to revise my family tree. There are now 3 nodes at the root: The PNA World, The RNA World, and Biota (or should it be Eubiota?) The first two items are flagged "hypothetical", "extinct" and "supposed precursors of all Biota".
Critiques: The technicalities are simply too overwhelming for the general reader. I won't comprehend the structure in the 1st paragraph without a diagram. Shouldn't it be a goal to present all molecular structures both as diagrammed formulas and as objects rotating in a reader-controlled panorama? (The technology exists, I think, but the work here is daunting.)
The 1st sentence in the 2nd paragraph is fine, but the rest of this 'graph is incomprehensible to a general reader (the sin of unexplained jargon). Wouldn't it be enough, comparing reactivity and stability, to say, for example, that double helix DNA comes apart at temperatures 20 Celsius lower than double chain PNA?
Are there such things as PNA catalysts (analogous to enzymes and ribozymes)? This would be of great significance for evolution.
If the PNA and RNA Worlds existed simultaneously, it is clear that PNA's lower reactivity and greater stability would allow the RNA World to gobble it up.
Could one say [gasp:anthropomorphic] that RNA still rules today, using DNA as a convenient, slowly mutating, copyable information store? If there were CPUs in the cell, would they be ribozymes? I see the ribosomes and some of the other things as distributed processors.
Solo Owl 01:42 Nov 4, 2002 (UTC)
It is true that some researchers have proposed that PNAs were progenitor molecules, but I don't think anyone actually takes that claim seriously. There is absolutely no evidence that PNAs ever existed outside of the lab, unlike RNA for which many natural ribozymes are known.
the addition of that part is unnecessary to the lead sentence. PNA does not exists in nature. Full stop. Why add the qualifier "present life"? With the same reasoning, endless strings of qualifiers may be added: in present life, nor on Venus, Mars, the moon Europe, nor in the past, but maybe in the future ......... Let's stick to the facts and do not load a simple sentence with wishful thinking, OR and POV. Northfox ( talk) 11:12, 6 February 2008 (UTC)
Northfox ( talk) 04:14, 7 February 2008 (UTC)
unindent. From the same lead aricle: "The lead should not "tease" the reader by hinting at but not explaining important facts that will appear later in the article." The fragment 'not known in modern life' hints that it was part of the biosphere in pre-modern life (whatever that you imagine that to be). Fact is that PNA is not part of life as we know it. And we don't know any other life forms. So we can only speculate about it. And we do so in the related paragraph furthe below. PNA is notable for very real medical (and related) research, not for a hypothetical precursor of RNA or DNA. Northfox ( talk) 11:35, 12 February 2008 (UTC)
I took the liberty to change the lead sentence. Biggest reason was that the 'but' makes the wrong connection. In the previous version, it modified 'modern life forms', but logically it should modify the 'occur naturally', by contrasting it to 'artificially synthesized'. Since User:ScienceApologist kept reverting me, I chose a different, more logical, order of statements. Also, "polymer" is better than "compound". Northfox ( talk) 08:23, 17 February 2008 (UTC)
quick addendum: we need to define 'modern life forms' here. There is no 'modern life' wikiarticle. Anybody with a good outside link? Northfox ( talk) 08:26, 17 February 2008 (UTC)
http://www.sciencedaily.com/releases/2012/11/121110093550.htm — Preceding unsigned comment added by Jjknack1 ( talk • contribs) 22:24, 11 November 2012 (UTC)