Dark reactions in eukaryotic and prokaryotic photosynthesis

The light-independent reactions of photosynthesis use the ATP and NADPH generated from the light reactions to synthesize carbohydrates from CO² and water. This is called the Calvin cycle. A key enzyme in this cycle is RuBisCo in Figure

                                                    Figure  .  The Calvin cycle.

a large multi-component enzyme. This enzyme incorporates CO² into ribulose 1, 5-bisphosphate to form first a six-carbon compound which then splits to form two three-carbon molecules. Subsequent reactions regenerate ribulose 1, 5-bisphosphate from one of the 3-phosphoglycerate molecules to continue the cycle. The other molecule of 3-phosphoglycerate is transported to the cytosol and used in respiration and to produce storage sugars.