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To: jennyp
Yes, the discovery of self-replicating RNA (ribozymes) about 20 years ago is what got RNA-world theory started, as I understand it

Your understanding is correct.

But there appears to be chemcial problems with the RNA World.

Something else to think about (from the link)

Furthermore, the relevance of ribozyme engineering to naturalistic theories of the origin of life is doubtful at best, primarily because of the necessity for intelligent intervention in the synthesis of the randomized RNA; then again in the selection of a few functional RNA molecules out of that mixture; then, finally, in the amplification of those few functional RNA molecules

A similar critque about the possibility of the RNA World can be found in the link in post 582.

623 posted on 06/15/2002 10:57:21 AM PDT by Tribune7
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To: Tribune7
Furthermore, the relevance of ribozyme engineering to naturalistic theories of the origin of life is doubtful at best, primarily because of the necessity for intelligent intervention in the synthesis of the randomized RNA; then again in the selection of a few functional RNA molecules out of that mixture; then, finally, in the amplification of those few functional RNA molecules

Every objection I have heard about RNA world, including your link, relies heavily on the chemical nature of discrete-cell reproduction. All I can suggest is that nobody really tries very hard to understand the nature of the notion being presented. If RNA world existed, it almost certainly did not have discrete cell reproduction, and almost certainly was not into high fidelity reproduction (How could it, without DNA?) And so it's chemical requirements were radically different than those of cellular entities. The arguments you have linked to are, to be kind, irrelevant. DNA world was constructed radically differently from ours. So the failure of the chemical world to provide things we cellulars find copesthetic is not a devastating argument against it.

What the version of RNA-world thesis I like best holds is that DNA packaged in single cells was just one of many things RNA world tried out, much as DNA world "tries out" various combinations of meat machines as DNA carriers.

In light of this, it is no more surprising that RNA-world managed to select DNA-carrying cellulars, than that guppy breeders can create lyre-tail guppies.

626 posted on 06/15/2002 1:33:47 PM PDT by donh
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To: Tribune7
Furthermore, the relevance of ribozyme engineering to naturalistic theories of the origin of life is doubtful at best, primarily because of the necessity for intelligent intervention in the synthesis of the randomized RNA; then again in the selection of a few functional RNA molecules out of that mixture; then, finally, in the amplification of those few functional RNA molecules

Every objection I have heard about RNA world, including your link, relies heavily on the chemical nature of discrete-cell reproduction. All I can suggest is that nobody really tries very hard to understand the nature of the notion being presented. If RNA world existed, it almost certainly did not have discrete cell reproduction, and almost certainly was not into high fidelity reproduction (How could it, without DNA?) And so it's chemical requirements were radically different than those of cellular entities. The arguments you have linked to are, to be kind, irrelevant. DNA world was constructed radically differently from ours. So the failure of the chemical world to provide things we cellulars find copesthetic is not a devastating argument against it.

What the version of RNA-world thesis I like best holds is that DNA packaged in single cells was just one of many things RNA world tried out, much as DNA world "tries out" various combinations of meat machines as DNA carriers.

In light of this, it is no more surprising that RNA-world managed to select DNA-carrying cellulars, than that guppy breeders can create lyre-tail guppies.

627 posted on 06/15/2002 1:34:02 PM PDT by donh
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