Calvin Cycle (C3 cycle).
The steps involved in C3 cycle are discussed below:
(a) Carboxylation : It is the fixation of CO2 into a stable compound. the reaction is catalysed by RuBP carboxylase enzyme. In this the ribulose 1, 5 -bisphosphate reacts with carbon dioxide to give 3-PGA (3 phosphoglyceric acid).
(b) Reduction : In this step carbohydrate is formed at the expense of ATP and NADPH. Two molecules of ATP are utilized for phosphorylation and two NAdph for the reduction of CO2 molecule fixed. 6 molecules of CO2 and 6 turns of cycle are required for removal of one molecule of glucose from pathway.
(c) Regenration - In this step the CO2 acceptor molecule RuBP is regenerated.