In the stroma

Also called the Calvin Cycle

ATP à ADP + Phosphate

  • RuBP combines with carbon dioxide from the air to form an unstable 6C compound
  • The enzyme RUBISCO catalyses the break down of the unstable 6C compound into two molecules of a 3C compound GP
  • NADPH is used to reduce GP to form a 3C sugar, GALP. The hydrogen for this reaction comes from the reduced NADP and energy required from ATP
  • For every 6 molecules of GALP produced, 5 continue in the cycle and combine with carbon dioxide to produce more RuBP using energy from ATP
  • The remaining GALP is converted to glucose for respiration
  • This is converted into sucrose for transport and polysaccharides such as starch for energy storage and cellulose for structural support
  • Glucose is also needed as a building block for amino acids, nucleic acids and lipids