I. REPLICATION OF DNA IN CELL-FREE SYSTEMS 



37 



Fig. 10. Proposed scheme of replication of a Watson and Crick DNA model. 

 Bold-lined polynucleotide chains of the two daughter molecules represent newly 

 synthesized strands. (From Josse et al., 1961.) 



OPPOSITE POUM^ITY 



TpA (.012) = TpA (.012) 

 ApG (.045) = CpT (.045) 

 GpA (.0(55) = TpC (.061) 



SIMILAR POLARITY 



TpA (.012) - ApT 1.030 

 ApG (.0,5) - TpC 1.061) 

 GpAi,.0o5) = CpT (.045) 



Fig. 11. Contrast of a Watson and Crick DNA model with strands of opposite 

 polarity with a model with strands of similar polarity. The predicted matching 

 nearest neighbor sequence frequencies are different. Values in parentheses are 

 sequence frequencies from the experiments with M. phlei DNA. The strands repre- 

 sented here are the newly synthesized strands of Fig. 10; for ease of comparison, 

 they are aligned as if they were complementary strands of the same double helix. 

 (From Josse et al., 1961.) 



