16MillionEyes - 26-2-2009 at 19:50
Perhaps a bit on the abstract and philosophical with respect with the overall experimental mood of the site, but this is the biochemistry section and
such subject should be fruitful here.
My inquiry starts with a rather dull request given the lack of appropriate resources (but I know some of you lucky people out there can access it!) to
get the full paper that can be found here http://www.sciencemag.org/cgi/content/abstract/1167856 and post it here so it can be read in full. This subject in general is rather interesting
in that it deals with one of the fundamental properties of life itself: self-directed replicability. The idea is actually somewhat simple and
obviously heavily based on DNA transcription itself regarding complementarity, except having the strand itself be its own decoding machinery. In other
words, this RNA strand acts as its own code and enzyme to make more of the same RNA strand! This seems like a solution to the chicken-egg paradox that
surrounds DNA transcription given its self-referenciability (I code for the mechanism that decodes the code itself, but how then can I decode myself
if I need a decoding mechanism that can only be produced by decoding the code itself?!). Obviously, after millions of years of trial an error a far
more complex and heavily contrived mechanism has evolved which yields little hints as to spark-start the fuse of life but such starting point had to
be there.
I think I could mumble about this forever, but the overall idea here is the inanimate basis of life yielding the inanimate. What are your ideas of
life with respect to this issue? Should we really remain attached deeply to the wells of social habit and anthropocentrism and overwrite the
underlaying basis of an otherwise undirected self-inducing steady-state phenomena - more or less like oppositely directing effects bring about stars
galaxies and so on - for a metaphysical supernatural self of immortality under considerations of self-divine right?
For moderators of the site: I wasn't so sure where to places this thread, but I thought here would be appropriate. And if there were other threads
like this, I apologize, although I do make a specific request here.
Sleep - 23-6-2009 at 03:08
There are alternatives to the self-replicating RNA molecule:
Consider 2 (or more) RNA molecules: A catalyses the replication of B and vice-versa.
The two molecules act as each other's (very primitive) ribosome.
One self replicating molecule is much more unlikely.
not_important - 23-6-2009 at 04:42
There's no 'decoding' going on in RNA/DNA replication; either a nucleotide is the matching pair of one in the xNA chain and fits into place, or it
isn't and keeps drifting about. Decoding happens in peptide synthesis, when nucleotide triplets are read to determine which amino acid to add next.
This is RNA World, of which there are much online writings. Alternatives include iron-sulphur membrane world, and Clay World. The Fe-S membrane
models do well at setting up early/simple "metabolic processes" that can build various organic molecules from simpler ones including just CO2 as a
carbon source. It's not at all incompatible with Clay World, as some of the conditions for Fe-S membrane formation are also effective for clay
synthesis. And neither rules out RNA World, as they are more tied to energy production and transfer while RNA is more about information replication.
Sleep - 23-6-2009 at 04:57
I agree but it's a definition thing. You could state that ribozymes are "encoded" in xNA, (gaining functionality after transcription and eventual
modification).
And then again, the triplet code is more of a cypher than a code.
But let's not split hairs shall we? 