[Taxacom] Robust argument

[bti at dsmz.de]

Bob,
>
> All three clauses are untrue. This kind of reasoning had a chemical  
> analogy in the 19th and early 20th century: organisms are only made  
> of atoms and molecules, there's no vital force; therefore everything  
> we can infer about how organisms work is inherent in atoms and  
> molecules, and if we could only completely understand the chemistry  
> we'd have the whole organismal story. Anyone still think that way?

Genomes are composed of nucleic acid bases, which consist of a pentose  
sugar back bone, phosphate and the appropriate nitrogen bases. The  
helical structure depends on the absoute stereochemistry of the  
pentose, the base pairing due to the bonding between the complementary  
nucleosides. t-RNA mediates protein synthesis by the same base-pair  
chemistry and the structure of proteins depends upon the individual  
amino acids present and their interactions, and we are also talking  
about "molecular machines". Try explaining membrane structure and  
functon by looking at genes alone.

Nearly forgot, the selection of D- or L-amino acids is by interaction  
of the t-RNA and the t-RNA amnio acid synthase. I have not been able  
to find any evidence that a codon specifies "L-amino acid" rather than  
"D-amino acid".

Brian

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