Chapter 1 



Ribonucleic Acids and Protein Synthesis 



1. BRIEF HISTORICAL SURVEY 



Next to nothing was known a quarter of a century ago about the 

 biological role and the intracellular localization of the nucleic acids. 

 All that was well established was the existence of two different types 

 of nucleic acids, which correspond to the deoxyribonucleic (DNA) 

 and ribonucleic (RNA) acids of the present day. They were called, 

 respectively, thymonucleic and zymonucleic acids, because purified 

 preparations had only been obtained from thymus and yeast. It 

 was erroneously believed that thymonucleic acid (DNA) is specific 

 to animal cells and that yeast nucleic acid (RNA) is present only in 

 plant cells. However RNA had been isolated from pancreas. A 

 popular hypothesis was that DNA, which was known to contain 

 both ortho-phosphoric acid and nitrogenous bases, might play the 

 role of an intra-nuclear buffer. Such a role is certainly a minor one 

 for the bearer of "genetic information"! 



One of the first important advances made in the field came from 

 cytochemistry, when in 1924 Feulgen and Rossenbeck designed and 

 utilized their well-known reaction for the detection of DNA. They 

 were immediately able to demonstrate that thymonucleic acid 

 (DNA) is specifically located in the cell nucleus, in plants as well 

 as in animals. 



Progress on the role and localization of RNA was slower to come, 

 because of the lack of specific cytochemical reactions comparable 

 to the Feulgen tests. Indirect observations by Brachet (1933) 

 strongly suggested, however, that animal cells may contain such 

 References p. 50/54 



