Figure 3.

The Calvin–Benson–Bassham cycle (CBBc) reactions. The CBBc has three stages. In stage 1, the enzyme RuBisCO incorporates 3 CO₂ molecules into the 5-carbon sugar ribulose-1,5-bisphosphate (RuBP) to form 6 molecules of 3-phosphoglycerate (3-PGA). In stage 2, 6 molecules of 3-PGA are converted into 6 molecules of Glyceraldehyde-3-P (G3P) by using 6 molecules of ATP and 6 molecules of NADPH as reducing power. In stage 3, RuBP is regenerated so that the cycle can continue. Stage 3 includes a complex series of reactions combining 3-, 4-, 5-, 6-, and 7-carbon sugar phosphates, which are not explicitly shown in the diagram.