308 



CHAPTER 34 



FIGURE 34-2. X ray diffraction photographs of suitably hydrated fibers of DNA, showing the so-called 



B configuration. A. Pattern obtained 



f^' using the sodium salt of DNA. B. Pat- 



tern obtained using the lithium salt of 

 DNA. This pattern permits a most 

 thorough analysis of DNA. (Courtesy of 

 Biophysics Research Unit, Medical Re- 

 search Council, King's College, London.) 





♦ ■ » , 



B 



FIGURE 34-3. The Watson-Crick dou- 

 ble-stranded helix configuration of DNA. 



