Oxidative Pathways of Carbohydrate Metabolism 151 



the biochemist. Until comparatively recently most discus- 

 sions of this kind were concerned with the inter-relationships 

 of the relative amounts of total carbohydrate, fat and protein 

 metabolized, but now in addition it has become necessary to 

 try to analyse the evidence indicating the preponderance of 

 one metabolic pathway over another for one and the same 



GLUCOSE 



ATP|l 



G6P 



-HPO;^ 



FDP; 



DHArHGASP': 



dpn|adp\ 

 PYRUVATE ' 



KREBS 

 ^CYCLE 



LACTATE CO2+H2O 



DPNH 



GLYCOGEN 



UDPG 



\ 2DPN 

 GLUCURONATE 



PentoseP^L-GULONATE 



ASCORBIC ACID 



REACTIONS 



GLYCOLYSIS 

 & KREBS CYCLE 



G6P- OXIDATIVE 

 &PENTOSE-P PATHWAYS 



URONATE 

 PATHWAY 



Fig. 1. Pathways of glucose metabolism in animal tissues. Only 

 essential intermediates are included in this diagram. 



major metabolite, and to try to discover those factors which 

 determine which of the alternative pathways is that favoured 

 by the cell under varying environmental conditions. 



Current views on probable metabolic pathways of carbo- 

 hydrate metabolism in animal tissues are summarized in Fig.l. 

 For detailed information on the development of knowledge 

 of these routes, a number of recent reviews are available 

 (Racker, 1954, 1957; Gunsalus, Horecker and Wood, 1955; 

 Dickens, 1955, 19586; Horecker and Hiatt, 1958). Micro- 

 organisms and plants which present in many cases an even 



