The Light Independent Reactions Also known as the Calvin Cycle Occurs in chloroplast stroma Energy to supply reactions comes from ATP and NADPH formed in the light reaction There are three major stages to the Calvin cycle: 1. Stage 1 - Carbon fixation CO2 from the atmosphere reacts with ribulose biphosphate RuBP) two 3C phosphoglycerate molecules (PGA) are produced. - catalyzed by RUBISCO (most abundant protein in nature) 2. Stage 2 - Reduction PGA molecules are phosphorylated using ATP and then reduced by NADPH to produce PGAL. 3. Stage 3 - Reformation of RuBP Some of the PGAL is converted to glucose (2 PGAL makes 1 glucose) - plants may use glucose as a building block to make other sugars, starch, fats, amino acids, nucleotides and other molecules Majority of PGAL is used to regenerate RuBP. - PGAL is converted to ribulose phosphate which is phosphorylated to form RuBP. Assignment: Summarize, in a chart, the following facts about the LIGHT INDEPENDENT REACTIONS (a.k.a. the Calvin Cycle): Location of the Light Independent Reactions Number of carbon dioxide molecules required to produce one glucose molecule Number of NADPH used to from one glucose molecule Number of ATP used to form one glucose molecule Source of ATP and NADPH for this series of reactions