48 



PHYSIOLOGY OF THE FUXGI 



would be of much more common occurrence than outside the cells. In the 

 medium the process of degradation may be expected to go more or less to 

 completion, since the soluble products of the reaction are assimilated by 

 the organism and hence equilibrium is not reached. Within the cell, 

 however, the reverse may be true. Here, the products of hydrolysis may 

 accumulate, a situation which would tend to favor the reverse reaction, or 

 synthesis. Therefore, synthesis within the cell would be expected to 

 occur when a plentiful supply of simple metabolite molecules continue to 

 reach the cell. When few, if any, metabolite molecules are entering the 

 cell, the hydrolysis of reserve materials would take place. These prod- 

 ucts of hydrolysis within the cell are then used in other metabolic processes 

 until the store of reserve material is exhausted. Some of these functions 

 are illustrated in scheme I. 



Scheme I. General Scheme of Starch Utilization 

 Outside the cell 



Starch 



->- Maltose 



*- Glucose 



amylase ^^■^^ ^-^^ maltase 



Fungus cells 



many enzymes 



Carbon dioxide, 

 alcohol and other 

 products of anaerobic 

 respiration 



Within the cell 



Glucose -<- 



many enzymes 



Carbon dioxide, 

 water and other 

 products of aerobic 

 respiration 



Glycogen, or 

 other storage 

 products 



Esterases. These enzymes catalyze the hydrolysis of esters, an acid 

 and an alcohol being formed. The most important natural esters are the 

 fats, which are the glycerol esters of the long-chain fatty acids. Enzymes 

 which catalyze the hydrolysis of fats are called lipases. Both exo- and 



