Enzymes 51 



the hexose monophosphate shunt that may be of particular im- 

 portance in the synthesis of ribonucleic acid (RNA) (Fig. 5) . 



Gljcojjen 



11 



Glucose y \> Glucose-6-Phosphate-< Glucose-1- Phosphate 



ATP ADP ^ ATP 



•ADP 

 Fructose 1-6 Diphosphate 



I 



Triose Phosphates 



I 



Phosphocjlyceric Acid 



I 



Phospho Pyruvate 



i 



Pyruvate 



Fig. 4. Diagrammatic Representation of Glycolysis. 



The major part of the cell's energy comes, however, from the 

 further breakdown of pyruvate to C0 2 and water. The first step is 

 the conversion of pyruvate to acetyl CoA, i.e. a complex between 

 the remains of the pyruvate molecule and coenzyme A. Electrons 

 lost in the process are transferred to diphosphopyridine nucleotide 

 (DPN) . Acetyl CoA then condenses with oxaloacetate to form 

 citrate which in turn loses electrons to triphosphopyridine nucleo- 

 tide (TPN) and also loses a carbon atom to become a-ketoglutarate. 

 The process is repeated and a ketoglutarate is converted to succinate 



