Genie and Non-genic Parts of the Chromosome 37 



for it. The stiffness of the DNA molecule and the presence of energy- 

 rich P-bonds may be additional properties in this relation to the 

 protein. The "stiffness" may serve to hold the peptide chains in an 

 extended form while they are being copied (meaning while a second 

 chain is laid down by a process akin to crystallization). A nice 

 detail, according to Butler, is that in the zigzag arrangement of the 

 phosphate groups there are two parallel rows. If a peptide chain 

 were held to one row, it may be supposed that a copy could be 

 laid down on the second: the function of the phosphate groups 

 would be to anchor the peptide, while the amino and hydroxyl groups 

 of the bases would keep the nucleic acids in a particular configuration 

 and so control the configuration of the protein. I shall refer later to 

 this general idea as the idea of the "scaffolding" function of the DNA 

 molecule, though in a certain sense it might also be joined to the 

 template concept. In view of the constancy of DNA, it should be 

 realized that this "scaffolding" process requires a constant quantity 

 of DNA to work with a definite amount and arrangement of proteins, 

 which have the actual genie functions, though the nucleoprotein com- 

 bination is an unavoidable prerequisite of genie duplication. 



Two new structural formulae have recently been proposed for 

 the nucleic acid molecule, both of which have a considerable bear- 

 ing on our subject. The first is that by Pauling and Corey (1953). 

 Basically the model is similar to the one used above, but the axis 

 of the molecule consists of three helices of closely packed phosphoric 

 acid tetrahedras held together by chains of ribose and the attached 

 pyrimidine and purine rings. This results in a very closely packed, 

 cylindrical, highly polymeric molecule of over a million molecular 

 weight. The geneticist, though awed, has diflBculty in seeing how this 

 could be the structure of the self-duplicating genie material, and is 

 inclined (while confessing his standing as a biochemical layman) 

 to conclude that he does not receive much help for his quest for 

 the genie material, either pro or contra DNA. 



Recently, however, a very ingenious and, as it seems, experimen- 

 tally well founded new structure for the DNA molecule has been 

 proposed by Watson and Crick ( 1953; see also Crick, 1954 ) which at 

 first sight seems to shift the scales very much in favor of DNA as the 

 genetic material. As the facts are rather exciting, they should be 

 clearly stated before trying to evaluate their genetic meaning. Wat- 

 son and Crick prepared fibers of a salt of DNA, which they consider 

 to be no artifacts because similar ones were obtained from sperm 

 heads and bacteriophage by Wilkins and Call. X-ray analysis showed 



