STRUCTURAL AND CHEMICAL ARCHITECTURE OF HOST CELLS 191 



In experiments involving the incorporation of ATP, it is suspected tliat 

 this reaction is the consequence of the intermediate formation of the adeny- 

 lates of amino acids. In the utilization of such compounds, the transfer of 

 amino acids to the intermediate soluble RNA fraction is perhaps accompanied 

 by a simultaneous transfer of the adenylic acid to the end of another RNA 

 chain, as shown in formula (XXXIV). 



Adenine Base Cytosine Base Cytosine Adenine 



IC COC COCOC 



3 COH C-O-P COH ^~°"f\ ^~°~^\ ^°^ 



5 C + O-C OH O-C >- O— C OH O-C OH O-C 



I + 



O Base Base Base Base 



HO P=0 COC COC 



O C-O-P. C— O-P C— O— P C— O— P 



C^O O-C OH O-C O-C O O-C 



R CNHj C=0 



R CNH2 



(XXXIV) 



In support of this view may be mentioned the experiment to show that 

 trace amounts of amino acid are required in chloramphenicol-inhibited bac- 

 teria for the synthesis of RNA, but not of DNA (Gros and Gros, 1956). In 

 an interesting study by Webster (1957b), it was found that ribonucleoprotein 

 particles isolated from pea seedlmg incorporate various RNA precursors, 

 such as adenine and uracil, in the presence of mitochondria, an oxidizable 

 substrate, ribose-5-phosphate, ATP, and Mg++, Incorporation was promoted 

 by a mixture of amino acids and was inhibited by amino acid analogs and 

 by hydroxylamine. These inhibitors did not prevent the early stage of 

 nucleotide formation. 



VII. Problems of Polymer Duplication 



For the purposes of this discussion we shall confine our attention to the 

 duplication of nucleic acids and proteins. Viral nucleic acids, both DNA and 

 RNA, can be infectious, and in infected cells compel the synthesis of viral 

 nucleic acid and viral protem. Therefore, these nucleic acids contain, within 



VOL. I — 14 



