90 



Martynas Ycas 



this process could be the building up of a complementary strand of DNA, as 

 in the Watson and Crick scheme for DNA reproduction (125).* 



Normally, the process stops at this stage, since the RNA molecule has 

 insufficient information to act as a template for itself. In the case of viruses, 

 however, the cytoplasmic process of adding new material to the original RNA 



Table VII. The Composition of the Protein and RNA of Viruses 



Composition of protein in moles per cent, of RNA as fractions of 1. t value 



assumed. It should be noted the influenza virus contains lipid, and the protein 



analysed may in part be of host provenance. 



results in the production of material identical to the template itself. From this 

 point of view, an RNA virus can be regarded as a specialized RNA molecule, 

 which because of restrictions on the sequence of 'proto-RNA' can act as its 

 own template, utilizing the normal RNA-synthesizing mechanism of its host. 

 The composition of the RNA of viruses lends some support to these ideas. 



* It is obvious that until more is known about RNA structure the question of its replication 

 can be discussed only in general terms. If RNA is a double-stranded structure, the nucleotide 

 composition shows that bases in the two chains cannot be uniquely paired as in DNA, but each 

 base must pair with one of two others, as shown by the equality of 6-keto and 6-amino groups 

 (89). In attempting to elucidate the details of RNA reproduction information on the number of 

 strands, whether each strand contains all the information of the whole structure, and where the 

 complementary strand is synthesized, is of crucial importance. 



