This is the state of things so far concerning my ideas on the origin of life
What we know helps narrow the search: 1. It is reasonable to see that a modified tRNA could become a mRNA at the anti codon end. But questions remain as to why the tRNA would join to amino acids and why either would be selected on account of it. 2. 2 genes code the tRNA, with one coding the acceptor stem. It suggests that this part came later. If so what preceded it? 3. There is no RNA in the enzymes that now join tRNA and AA's. How could these be there in the RNA world or before, without any RNA? It suggests that they were not and there was some direct bond between the proto tRNA and AA's 4. Is there a second anticodon lurking in the tRNA? I tend to think there is one at the TYC loop. It mimics many of the same features as the anticodon and it is situated at the opposite end as if the molecule h-bonded two other molecules at one time with one on each end 5. There evolved a symbiosis between the tRNA and AA's, but why. What was the selective advantage at that place and time. 6. The genetic code (anticodon -- codon) doesn't seem to have a direct connection to the AA's on the other side. But it must have at one time. What was it?
Clues that help: 7. h-bonding sets up many of the variants that are then selected in a thermal cycle. 8. solutions for aspects of the origin so far, are partially right but are not completely right and are obviously missing something 9. Initial code was phobic/phillic split probably 10. Monomers produced in a heat cycle or thermal cycle 11. Some polymerization in a heat cycle is possible (with a dry/wet cycle too)
That's where I am. Anyone like to comment on which points are reasonable and which are not?
<< This is the state of things so far concerning my ideas on the origin of life (snipped)
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Along these lines, it is interesting to note what John Maynard Smith writes in "The Problems of Biology about the basic origin of life problem. ('86) I read it today and found it very similar to the one I suggested though much better written:
"There remains one further difficulty which may be the most severe of all: the relation between proteins and nucleic acids. Nucleic acids can replicate, but they are enzymically inert: chemically, they do not do anything interesting. Proteins are marvellous catalysts, but cannot replicate. Life depends on combining these two functions. Today the connection is made via the genetic code, and the process of directed protein synthesis. In this process the esssential step, that in which an AA is attached to a particular tRNA. The specificity of this attachment is achieved by an enzyme. This arrangement cannot be primitive. The first binding of amino acids to nucleic acids must have occured in the absence of informed enzymes. At present we have little idea of how this could have happened; indeed, little is known of the chemistry of aa-nucleic acid interactions..."
On Mon, 27 Oct 2003 16:42:09 +0000 (UTC), [email hidden]
(TomHendricks474) said:
<< This is the state of things so far concerning my ideas on the origin of life (snipped)
Quoted message said:
Quoted message said:
Along these lines, it is interesting to note what John Maynard Smith writes in "The Problems of Biology about the basic origin of life problem. ('86) I read it today and found it very similar to the one I suggested though much better written:
"There remains one further difficulty which may be the most severe of all: the relation between proteins and nucleic acids. Nucleic acids can replicate, but they are enzymically inert: chemically, they do not do anything interesting. Proteins are marvellous catalysts, but cannot replicate. Life depends on combining these two functions. Today the connection is made via the genetic code, and the process of directed protein synthesis. In this process the esssential step, that in which an AA is attached to a particular tRNA. The specificity of this attachment is achieved by an enzyme. This arrangement cannot be primitive. The first binding of amino acids to nucleic acids must have occured in the absence of informed enzymes. At present we have little idea of how this could have happened; indeed, little is known of the chemistry of aa-nucleic acid interactions..."
Yep - that' the rub!
Tom Hendricks
It was right about the time John Maynard Smith wrote this (1986?) that ribozymes had been discovered (Cech 1982) and it is no longer true to say that RNA is "...enzymically inert: chemically, they do not do anything interesting". The whole concept of an 'RNA world' followed. The first binding of amino acids to nucleic acids must have occured in the absence of informed protein enzymes but there well may have been informed rna ribozymes to perform this function. There is no presence of rna in aminoacylation sites today but this does not mean rna was never involved. William L Hunt
