Reproduction of the Genetic Material 29 



DNA 29 



Production of an RNA template from DNA 32 



Reproduction of RNA 32 



Conclusions 33 



IV. THE FUNCTIONAL ORDER 35 



The Problem 35 



Two Models of Enzyme Synthesis 37 



Induction 37 



Repression 38 



The Genetic Control of Bacterial Metabolism 39 



Metabolism of lactose 39 



Variations 41 



The gene as a unit; sexual digression 43 



Altered enzymes 43 



Induction and Repression 46 



Generalized induction hypothesis 46 



The repressor 46 



The Ways of Repression 49 

 Repressor, aporepressor, corepressor, and inducer; 



the control of enzyme syntheses 49 



Amino acids 49 



Carbon and energy source 53 



The operator 54 



Co-ordinated control 58 

 Refinement of regulation; inhibition of enzymatic 



activity 58 

 Preclusive and corrective feedback 



mechanisms 58 



Conclusion 60 



V. VIRAL FUNCTIONS: ORDER AND 



DISORDER 62 



Introduction 62 

 Viral order: the infectious viral particle, or 



virion 63 



The virus 65 



Remarks on the control of viral functions 65 



Bacteriophage 66 



Life-cycle of a virulent bacteriophage 66 



The temperate bacteriophage; lysogeny 68 



[X] 



