Pyrimidine Moieties in Animals, Plants, and Bacteria 121 



First, the whole question of the ions is an extremely important 

 one. Ions are bound to the phosphoric acid groups of the nucleic 

 acid molecules. Possibly, they are involved in the regulation of 

 gene function. A DNA molecule has two functions — either to 

 serve as a template for its own replication — or to serve as a tem- 

 plate for the replication of RNA. What controls these alternative 

 functions? What are the controls which determine which and how 

 many of the present cells will be functional? The answer to these 

 questions possibly lies in the interaction between the nucleic acids, 

 cations, and certain proteins. Nucleic acid configuration and 

 length may be greatly modified by the ionic environment in which 

 the nucleic acid is found. This process may thus regulate some of 

 the cellular biosynthesis. 



There was a point brought out in the discussion of Dr. Echol's 

 paper that should be made more explicit. It is possible that nucleic 

 acids function in the spread of information among cells. This may 

 be accomplished either by the free nucleic acids or by the viral 

 nucleic acids. The latter may be thought of either as messengers 

 or as transducing viruses. Herriot, in particular, has been in- 

 terested in the biological significance of extracellular nucleic acids. 



Mike McGlothlen (Houston, Texas): In the synthesis of RNA, 

 the DNA would carry a code dictating the formation of RNA, 

 which in turn dictates the formation of proteins. Your last slide 

 showed the RNA forming on the DNA template a homologous 

 process to that proposed for reproduction of DNA. Why do you 

 have to have this apparent splitting of hydrogen bonds? Why not 

 have a similar code mechanism in the DNA, such as two or three 

 units of the DNA chain dictating the reproduction of one unit of 

 the RNA chain? Why the same mechanism for the production 

 of RNA and DNA from a DNA chain, rather than two different 

 methods involving dissimilar codes? 



Heather D. Mayor (Houston, Texas): I think this question 

 results from difficulty in understanding the diagram. We do not 

 really know whether one part of the molecule is busy transcribing 

 RNA, while at the same time the rest of it is replicating DNA. 

 Even though these points are not settled, such a diagram is useful 

 for the purpose of documenting what is known to be going on. 

 It simply indicates the double helix coming apart in this manner 



