CELLULAR BIOCHEMISTRY 



Complexities of Organization 



Even if it is granted that the different chemical operations 

 of the cell are carried out as if they were spatially separated, one 

 has dealt with only a small part of the complexity of the system. 

 The inherent capacity of the cell to duplicate itself and to exert 

 a seemingly purposeful control over its function has made it 

 difficult to assert that the ordinary laws of physics and chem- 

 istry apply — a difficulty which the microcosm shares with the 

 macrocosm. One may take as an example the following 

 dilemma. The accretion of material of exactly the same molec- 

 ular structure prior to division of the chromosomes and the 

 control exerted by this structure on the formation of specific 

 enzymes starts an unending causal chain, where one enzyme is 

 necessary for the formation of another enzyme and so on. In 

 order to break this chain, it is necessary to introduce a non- 

 enzymatic step, either in the process of self-duplication of 

 genetic material or in the formation of the first enzyme of a 

 chain. When faced with such complexities, it is not surprising 

 that some biologists prefer to invoke the operation of special 

 vital forces which they believe are peculiar to living matter. 

 This point of view also finds its expression in statements to the 

 effect that enzymes studied in vitro after extraction from the cells 

 are not the same entities which act in the intact cell. Granted 

 that this may be true in certain cases, one would rather investi- 

 gate the reason for such deviations than be discouraged about 

 the validity of the methods that enzyme chemists have used. 



The higher forms of organization in multicellular organ- 

 isms are characterized by the increasing complexity of regulatory 

 mechanisms on the evolutionary scale. One finds specialization 

 of chemical operations according to cell types assembled in 

 organs, increasing control through the central nervous system, im- 

 proved transport of materials to and from the cells through the 

 development of the circulatory system, and finally the elabora- 

 tion of highly active and specific substances, the hormones, 

 which exert a control over enzymatic processes. A remarkably 

 constant internal environment has been achieved through the 



207 



