Calvin Cycle

This was discovered by Melvin Calvin and associates for which he won the Nobel Prize in Also known as the Dark Reactions or the Light-Independent Reactions.

Calvin Cycle This is where glucose is created from water and carbon dioxide. Requires no light energy The Calvin Cycle begins and ends with a 5C molecule called Ribulose Bisphosphate (RuBP).

1) Carbon Fixation ATP and NADPH from the light reactions go into the stroma of the chloroplast where the Calvin Cycle occurs. 6 RuBP captures 6 atmospheric carbon dioxide molecules and reacts with water to form twelve 3C molecules of phosphoglyceric acid (PGA). This step is catalyzed by the enzyme RuBisCO.

1) Carbon Fixation This first stage is known as carbon fixation because it takes atmospheric carbon and fixes it into an organic molecule.

2) Reduction The second stage is where the energy (12 ATP) and the reducing power (12 NADPH) are used to convert 12 PGA into 12 glyceraldehyde- 3-phosphate (G3P).

2) Reduction Two G3P molecules then combine to form glucose. ***THIS IS NOT THE ENTIRE TRUTH*** In fact the G3P molecules can be used to synthesize many different molecules for the plant… but forget I said anything…

3) Regeneration The other ten G3P molecules and the remaining energy from the light reactions (6 ATP) are used to arrange the remaining 10 G3P back into 6 RuBP, so the cycle can start anew.