CHAPTER 

 IV 



GENETIC CONTROL OF PROTEIN SYNTHESIS 



Harrison Echols, Ph.D. 



INTRODUCTION 



kjOME ten years ago the work of Beadle, Tatum, and Horo- 

 witz (1) led to the famous "one gene-one enzyme" hypothesis, 

 which asserted that gene control over cell metabolism is exerted 

 through genetic determination of the structural specificity of 

 enzymes. I would like to discuss our present knowledge and 

 beliefs concerning genetic control of protein synthesis by starting 

 with this concept of the "structural gene" and inquiring into the 

 chemical nature of the gene and into the process by which the 

 gene controls protein specificity. Finally, I shall briefly consider 

 the concept of "regulatory genes" concerned with controlling the 

 rate of action of the structural genes. 



CHEMICAL IDENTIFICATION OF GENES 



It is now generally accepted that deoxyribonucleic acid (DNA) 

 stores the genetic information of the cell. The evidence for this 

 comes chiefly from work with bacteria and bacterial viruses, and 

 is based primarily on three types of genetic transfer experiments: 

 transformation, virus infection, and bacterial conjugation (2). In 

 transformation experiments purified DNA extracted from one 

 bacterial population has been shown to carry genetic information 

 to another bacterial population. For example, DNA from a strain 

 of Bacillus sub til is which possesses the ability to synthesize the 

 amino acid tryptophan can confer this biosynthetic ability on a 



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