4 THE BIOSYNTHESIS OF PROTEINS 



At the time of writing, no single problem of protein biosynthesis is com- 

 pletely solved, but the problems at least are clearly stated. The technology 

 of protein biosynthesis is partly understood ; the systems which supervise 

 and control the process are being eagerly investigated and some of the key 

 principles upon which they operate are known already. Nucleic acids are 

 all important in these systems. Here chemistry and genetics meet and a 

 new fascinating field opens: molecular biology. 



Maximum radius 



20A -^— Radius of hole 



Nucleic acid 



Fig. 5. Schematic representation of a tobacco mosaic virus. The protein 



units form a hollow rod with the nucleic acid fibre embedded in the 



protein material (Franklin et ah, 1957). 



