[email protected] (TomHendricks474) wrote in message news:<
[email protected]>...
> I read this quote from a textbook with 2000 c.
>
> "Graham Cairnes-Smith (suggests that) RNA nucleotides and
> amino acids became associated in such a way that
> polypeptides were ordered by and helped synthesize
> RNA...This hypothesis suggests that both polypeptides and
> RNA arose at the same time."
>
> I tend to agree that they did. I did not know that Cairnes
> - Smith did too. Does anyone know exactly how he thought
> the two might arise at the same time and under what
> conditions?
Tom, Since you found a quote from Tim's hero that kind-of
supports your views, I thought you might be interested in a
couple of papers from two of my FeS heros that also kind-of
support you. Jim
An All-Purine Precursor of Nucleic Acids Gunter
Wachtershauser Proceedings of the National Academy of
Sciences of the United States of America, Vol. 85, No. 4.
(Feb. 15, 1988), pp. 1134-1135. Stable URL:
http://links.jstor.org/sici?sici=0027-
8424%2819880215%2985%3A4%3C1134%3AAAPONA%3E2.0.CO%3B2-H
Abstract The theory is proposed that the pyrimidines in
extant nucleic acids are postenzymatic substitutes for their
isoelectronic and isogeometric position 3-bonded purine
analogs xanthine and isoguanine, which were sibling products
in a preenzymatic de novo purine pathway.
Selection by Differential Molecular Survival: A Possible
Mechanism of Early Chemical Evolution Christian De Duve
Proceedings of the National Academy of Sciences of the
United States of America, Vol. 84, No. 23. (Dec. 1, 1987),
pp. 8253-8256. Stable URL:
http://links.jstor.org/sici?sici=0027-
8424%2819871201%2984%3A23%3C8253%3ASBDMSA%3E2.0.CO%3B2-P
Abstract A model is proposed to account for selective
chemical evolution, progressing from a relatively simple
initial set of abiotic synthetic phenomena up to the
elaborately sophisticated processes that are almost
certainly required to produce the complex molecules, such as
replicatable RNA-like oligonucleotides, needed for a
Darwinian form of selection to start operating. The model
makes the following assumptions: (i) that a small number of
micromolecular substances were present at high
concentration; (ii) that a random assembly mechanism
combined these molecules into a variety of multimeric
compounds comprising a wide repertoire of rudimentary
catalytic activities; and (iii) that a lytic system capable
of breaking down the assembled products existed. The model
assumes further that catalysts supplied with substrates were
significantly protected against breakdown. It is shown that,
by granting these assumptions, an increasingly complex
network of metabolic pathways would progressively be
established. At the same time, the catalysts concerned would
accumulate selectively to become choice substrates for
elongation and other modifications that could enhance their
efficiency, as well as their survival. Chemical evolution
would thus proceed by a dual process of metabolic extension
and catalytic innovation. Such a process should be largely
deterministic and predictable from initial conditions.