 The cycle builds sugar from smaller molecules by using ATP and the reducing power of electrons carried by NADPH  The Calvin cycle has three phases: › Carbon fixation (catalyzed by rubisco ) › Reduction › Regeneration of the CO 2 acceptor (RuBP)

 Joining carbon from the atmosphere into an organic compound  Rubisco combines 3 CO2 with 3 RuBP (a 5 carbon sugar) forming 3 unstable 6 C molecules  3 Unstable 6 C split into C molecules of PGA

 Use energy from ATP and NADPH to reduce 6 PGA (6 – 3C) into 6 G3P (6 – 3C)  1 – 3C G3P leaves the cycle (eventually is can join with another 3C G3P to form 6C Glucose  5 – 3C G3P stay in the cycle

 Use ATP to convert 5 – 3C molecules back into 3 – 5C molecules

 What are the products? › G3P, ADP + Pi, and NADP+  How much CO 2 must be fixed to form glucose? › 6 CO 2  What is oxidized? › NADPH to NADP+  What is reduced? › CO 2 to G3P eventually Glucose

 Where are the reactants used? › CO 2 – Calvin Cycle › H 2 O – Light Reactions › Light – Light Reactions  Where are the products produced? › O 2 – Light Reactions › C 6 H 12 O 6 – Calvin Cycle