A NEW CONCEPT OF RIBONUCLEIC ACIDS 



WALDO E. COHN, Biology Division, Oak Ridge National Laboratory, 



Oak Ridge, Tennessee 



When progress in a particular fragment of science is viewed 

 in retrospect, there seem to be periods when advances are so few 

 and widely separated as to give an impression of finality, and 

 other periods when, again in retrospect, new discoveries and 

 interpretations come at a rate which seems to imperil accuracy 

 of experimentation and of interpretation alike. It is tempting 

 to draw an analogy between this semidiscontinuous process and 

 the biological one of gestation and birth. However, this implies 

 a degree of smoothness of progress which, on close inspection, 

 is not warranted. Perhaps a better analogy is that of geyser 

 eruption, in which a quiet period is followed by an apparently 

 uncoordinated discharge of material. 



In specific reference to the changes in our concept of the 

 structure of ribonucleic acid (RNA) since 1949, this analogy 

 might be pushed even further to include the mild play of the 

 water between eruptions and the autocatalytic nature of the 

 eruption itself. Certainly there were indications, prior to 1949, 

 that the structure proposed in 1935 (45) (see Figure la), linking 

 the ribose moieties with diesterified phosphate from the second 



* Manuscript prepared under Contract No. W-7405-eng-26 for the 

 Atomic Energy Commission. 



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