108 Information Storage and Neural Control 



TABLE XIII 



Base Composition of Ribonucleic Acids of Viruses 



41.4 to 50.9 mole per cent (G + C) (Table XIII). Many DNA 

 viruses have similar values (Tables VII through IX). 



Messenger-RNA (Also called Informational-RNA and Com- 

 plementary-RNA and Abbreviated C-RNA) 



The lack of correlation between DNA nucleotide composition 

 and ribosomal nucleotide composition provided a paradox for 

 some time. It was believed that genetic information was coded in 

 DNA but that the actual assembling of amino acids into proteins 

 occurred on the ribosomes. The fact that proteins are not syn- 

 thesized directly on the genes demanded the existence of an inter- 

 mediate information carrier. This intermediate information carrier 

 was generally assumed to be ribosomal-RNA. However, it was 

 difficult to reconcile this with the following facts: 1) ribosomal- 

 RNA is relatively stable; 2) it is remarkably homogeneous in size 

 and in nucleotide composition although this homogeneity reflects 

 neither the range of size of polypeptide chains nor the variation 

 in nucleotide composition observed in the DNA from different 

 sources; 3) the capacity of bacteria to synthesize a given protein 

 does not survive beyond the integrity of the corresponding gene; 

 and 4) regulation of protein synthesis in bacteria seems to operate 

 at the level of the synthesis of the information intermediate by 

 the gene rather than at the level of the synthesis of the protein 

 (4, 27). 



