During light independent reactions, which are also referred to the Calvin cycle, uses the ATP and NADPH produced from the light dependent reaction as a source of energy to transform carbon dioxide into a carbohydrate. This reaction does not require energy from photons thus is able to occur without sunlight. The Calvin cycle begins in the stroma. Carbon fixation takes place to fix a carbon dioxide molecule onto ribulose biphospate (RuBP), forming an unstable molecule. This molecule breaks apart to regain stability, thus forming two molecules of 3-phosphoglycerate. Reduction will then take place as ATP donates a phosphate group onto the 3-phosphoglycerate and the NADPH donates electrons in the form of H+ ions. This forms 2 molecules of Glyceraldehyde
