-FIP- 



CO2 Reduction- 

 Cycle 



F6P 



Sucrose 

 Sucrose P 



G6P 



UTP 



Starch 



GIP: 



r:UDPG=::iUDPGal^;=rGal IP 



PP 



Oligosaccharides 

 Polysaccharides 



Figure 8. Biosynthetic pathways for photosyn- 

 thesis of carbohydrates. 



were formed when radioactive glucose- 1 -phosphate, fructose- 

 6-phosphate, and UTP were added. They propose a mecha- 

 nism identical to that postulated by Buchanan except for the 

 choice of fructose-6-phosphate as the precursor instead of 

 fructose- 1 -phosphate. 



Not much is known about the formation of other poly- 

 saccharides. There is a rapid labeling of unidentified polysac- 

 charides during photosynthesis with C^^Oo. On the usual two- 

 dimensional chromatogram, developed as described earlier, 

 these compounds form what appears to be a homologous series 

 of polyglucoses extending from the origin nearly to sucrose. 

 The compound of this series closest to sucrose has been hy- 

 drolyzed and found to contain only glucose. 



55 



