ENERGY TRANSFORMATION 



411 



All reactions, except the fourth one, actually take place and the prod- 

 ucts of oxidation can be determined from the amount of sugar and 

 oxygen consumed. The ratio of C0 2 to 2 , or the respiratory quotient, 

 is equal to zero in most of the above equations. When the quotient 

 is less than 1, the oxidation is incomplete. With complete oxidation, 

 C0 2 :0 2 = 1. 



In the oxidation of alcohol to acetic acid, C0 2 :0 2 = 0, but with 

 complete combustion, C0 2 :0 2 = 0.67, 



C 2 H 6 OH + 3 2 = 2 C0 2 + 3 H 2 + 326 Cal. 



In the oxidation of tartaric acid, the C0 2 :0 2 = 1.6, 



C 4 H 6 Oe + 2| 2 = 4 C0 2 + 3 H 2 + 262 Cal. 



In the oxidation of palmitic acid, the C0 2 :0 2 = 0.7, 



Ci 6 H 32 2 + 23 O2 = 16 C0 2 + 16 H 2 + 236 Cal. 



The oxidation of nitrogen compounds gives quotients smaller or 

 greater than 1. 



C 6 Hi 3 NC>2 + 7\ O2 = 6 CO2 -f 5 H 2 + NH 3 + 775 Cal. 

 Leucine C0 2 :0 2 = 0.8 



C2H5NO2 + 1J 2 = 2 C0 2 + H 2 + NH 3 + 152 Cal. 

 Glycocoll C0 2 :0 2 = 1.33 



The oxidation of proteins, which consist of the different amino acids, 

 will, therefore, give a quotient falling between the two above equations, 

 becoming 1 with complete oxidation. Usually, it is less than 1 and 

 may even be when oxidation stops at the oxalic acid stage. Some 

 of the oxygen may be used up for the oxidation of nitrogen and sulfur 

 compounds, as in the case of the action of the autotrophic bacteria 

 when the respiratory quotient equals 0. 



Puriewitsch 51 calculated the respiratory quotient for Asp. niger, using 

 different sources of energy: 



61 Puriewitsch, K. Physiologische Untersuchungen iiber Pflanzenatmung. 

 Jahrb. wiss. Bot., 35: 572-610. 1900. 



