8o THE METABOLISM OF ALGAE 



COOH CO.NH2 



I ! 



(CH,)2 (CHa)^ 



ATP + I + NH3— >ADP + H3PO4 + I . (23) 



CH.NH2 CH.NH2 



COOH 

 Glutamic acid 



COOH 



Glutamine 



The mechanism of amide formation in algae must be sup- 

 posed to be essentially similar. 



A' 



Polysaccharide 



^ Organic acids ^ 

 fi 



CO., 



Amino-acids - r^Amide 



A' 



A' 



Glucose 



Protein 



FIG. 



14. Scheme showing the probable inter-relationships between 

 the processes involved in ammonia assimilation in Chlorella 

 vulgaris. A represents a substance such as adenosine diphos- 

 phate and A', a substance such as adenosine triphosphate 

 (after ref. 277). 



It will be evident from the preceding paragraphs that 

 the mechanisms of ammonia assimilation and respiration are 

 interdependent. The correlation existing between the rates 

 of the two processes may be explained if it is assumed that 

 the rate of respiration is normally limited by the amount 

 available of some substance, such as adenosine diphosphate, 

 which can act as an acceptor for the high energy phosphate 

 groups produced in this process.^"^ It has been pointed out 



