180 UNITY AND DIVERSITY IN BIOCHEMISTRY 



The cell is the place where an important series of reactions occur which 

 we shall term priming reactions since their purpose is the formation of the 

 energy-rich linkages of ATP. These reactions are the most important 

 mechanism for the provision of these energy-rich bonds. They are not 

 what were formerly known as catabolic reactions, but they consist of 

 a series of closely interrelated cycles which are more or less reversible. As 

 the cellular nutrients are metabolized and consumed in these cycles, a 

 certain number of energy-rich bonds are formed, some new molecules are 

 synthesized and above all, the cell is provided with a series of fragments 

 containing one, two or more carbon atoms. These fragments can serve as 

 building blocks for the construction of many different molecules which 

 can be incorporated into the structure and functioning of that particular 

 organism. 



