STRUCTURAL AND CHEMICAL ARCHITECTURE OF HOST CELLS 17 



E. The Biosynthesis of Nucleic Acid Intermediates 176 



1. Scavenging Reactions 176 



2. De Novo Synthesis 177 



F. Biosynthesis of the Nucleic Acids 1 83 



1. The Structure of the Nucleic Acids 183 



2. The Biosynthesis of RNA 186 



3. DNA Synthesis 189 



4. Nucleic Acid Synthesis in Extracts of Animal Tissues 190 



VII. Problems of Polymer Duplication 191 



A. DNA Duplication and Partition 192 



B. The Transfer of Biological Information 196 



1. DNA as a Template 196 



2. RNA as a Template 197 



3. The Problem of Polypeptide Order 201 



VIII. Conclusion 202 



References 203 



I. Introduction 



A virologist must liave cells to practice liis discipline and he should be a 

 cellular biologist before approaching problems of virus infection. He must 

 understand cell parts, their composition, functions, and interactions, as well 

 as the duphcations of the parts which result in the multiplication of cells. 

 AU synthetic processes relevant to these biological phenomena are relevant 

 to the virologist. 



This chapter should therefore be a text of cellular biochemistry, although 

 written with an eye to the special interests of virologists. In a summary of 

 the biochemistry of cells and cell parts, the virologists would presumably 

 wish to learn of the synthetic reactions that can be of particular interest in 

 analyzing the behavior of infectious particles that are synthesized within 

 cells. This is the task that has been assumed, i.e., to summarize the present 

 state of cellular biochemistry, with particular reference to the syntheses 

 which may be involved in the production of viral components and viruses. 

 However, a number of relevant areas have been neglected in recognition of 

 the restriction of space. 



A. Historical Notes 



Early chemical virology was confined to the study of the properties of 

 isolated viruses. Following the crystallization of tobacco mosaic virus by 

 Stanley (1935) and the detection of nucleic acid in purified preparations of 

 this virus by Bawden et al. (1936), work developed around the isolation and 

 the chemical and physical characterization of other plant viruses. In addition, 

 the isolation and characterization of purified preparations of a bacteriophage, 

 vaccinia virus, rabbit papilloma virus, and other viruses were soon reported. 



