part of carbon fixation reductive pentose-phosphate cycle Calvin cycle See also the molecular function term 'ribulose-bisphosphate carboxylase activity ; GO:0016984'. GO:0019253 The fixation of carbon dioxide (CO2) as glucose in the chloroplasts of C3 plants; uses ATP and NADPH formed in the light reactions of photosynthesis; carbon dioxide reacts with ribulose 1,5-bisphosphate (catalyzed by the function of ribulose-bisphosphate carboxylase) to yield two molecules of 3-phosphoglycerate; these are then phosphorylated by ATP to 1,3-bisphosphateglyceraldehyde which, in turn, is then reduced by NADPH to glyceraldehyde 3-phosphate. The glyceraldehyde 3-phosphate is converted to fructose 5-phosphate and ribulose 5-phosphate by aldolase and other enzymes; the ribulose 5-phosphate is phosphorylated by ATP to ribulose 1,5-bisphosphate. biological_process C3 photosynthesis MetaCyc:CALVIN-PWY photosynthesis, dark reaction