Life: Its Nature and Origin 



41 



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fjS^'l 



(b) 



(c) 



Fig. 18. Possible arrangement of protamine and DNA in strands of the 

 mature nucleus, (a) Scheme of a chromonema strand, composed of a sequence 

 of threadlike monomers (nemameres) The interrupted line represents other 

 components which may exist in chromosomes during some stages of the cell 

 cycle, (b) Longitudinal section of one monomer of (a). The nemamere is not 

 represented to scale; only parts of the chains, in length and in diameter, are 

 shown. Nucleic acid chains are represented as double helices and protein 

 chains as single helices. The chains are folded many times, although their dis- 

 position along the chromonema axis predominates. At the junctions of con- 

 tiguous nemameres dots represent types of compounds which help in the 

 bonding of such monomers, which should take place, however, chiefly through 

 secondary forces, (c) Scheme of two genie sites with specific geometry, com- 

 posed of mutually adapted protamine chains and complementary nucleic acid 

 chains. (After Serra.) 



division restore the molecular machines that initiate a new period 

 of growth. 



There is little doubt that the molecules in the cell must be 

 arranged in a precise physical architecture. Otherwise, it is dif- 

 ficult to conceive of the proper molecules being in reactive posi- 

 tions which will permit the even flow of chemical reactions neces- 

 sary for the rapid growth exhibited by many cells and especially 

 for the operation of the many "molecular machines" which are 

 cyclic in nature. Indeed, this consideration suggests that the interior 



