MOLECULAR CONFIGURATION OF NUCLEIC ACIDS 



double-helix is present in inert genetic material in sperm and bacteriophage, 

 and in cells slowly or rapidly dividing or secreting protein (Hamilton ctal. 16 ). 

 No difference of structure has been found between DNA from normal and 



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Fig. 5. X-ray diffraction photograph of DNA fibres (B configuration) at high humid- 

 ity. The fibres are vertical. The 3.4 A reflection is at the top and bottom. The angle in 

 the pronounced X shape, made by the reflections in the central region, corresponds to 

 the constant angle of ascent of the polynucleotide chains in the helical molecule. 

 (Photograph with H. R. Wilson; DNA by L. D. Hamilton.) 



s-42 



