HIERARCHY OF CELLULAR CONSTITUENTS 101 



there is not sufficient evidence for so singling out this particular 

 class of substances. 



We know that autarkic entities (cells and cell communities) 

 require the presence of a very large number of different com- 

 pounds, foremost among which are the ubiquitous plastic con- 

 stituents, namely: (1) nucleic acids (both of the deoxypentose 

 and pentose types, DNA and PNA); (2) proteins; (3) lipids; 

 (4) polysaccharides. Parasitic systems (viruses, phages) apparent- 

 ly require the presence of nucleic acids (DNA or PNA) and 

 protein. But such a generic statement probably is no more 

 meaningful than if we were to say that all machines consist of 

 iron, copper, nickel, etc. For neither the knowledge of quantity 

 nor that of quality alone can satisfy our inquiry; and for an 

 understanding of what is meant by organization an entirely new 

 dimension will have to be added: a dimension of which barely 

 the foundations are discernible at present. Moreover, to return 

 to the example of the machine, it is not likely that we could learn 

 much about the "origin of the automobile" from an inspection of 

 the parts of a present-day car; nor could such an examination 

 help us to decide whether there did not once exist an automobile 

 made of glass, though we may conclude that, at any rate under 

 present conditions, it would hardly have survived as the fittest 

 means of locomotion. 



In any event, even if we commit the oversimplifying fallacy of 

 postulating a virus-like structure as the first "living" molecule, 

 we are still left to deal with a nucleoprotein: a singular that 

 conceals a multitude of possible structures. If scientific facts were 

 subject to a vote, the majority opinion would probably place the 

 nucleic acids at the top of the hierarchy and let the proteins fol- 

 low; something like this: DNA -> PNA -» protein. But in my 

 opinion it would be more honest to confess that we know very 

 little indeed about these things and to say that the road to the 

 future should not be uselessly cluttered up with shoddy, and 

 often entirely baseless, hypotheses. It may, however, not be un- 

 instructive to say a few words about the chemical connotations of 

 the concept of biological information. 



References p. 108 



