13.1.2 Stages of Photosynthesis

• Photosynthesis occurs in two stages:
  • The light-dependent stage, which takes place in the thylakoids
  • The light-independent stage, which takes place in the stroma

Summary of the light-dependent stage 

• Reduced NADP is produced when hydrogen ions combine with the carrier molecule NADP using electrons from the photolysis of water
• ATP is produced  in a process called photophosphorylation 
  • Photophosphorylation uses the proton (H⁺) gradient generated by the photolysis of water
• Energy from ATP and hydrogen from reduced NADP are passed from the light-dependent stage to the light-independent stage of photosynthesis

Summary of the light independent stage

• The energy and hydrogen (from the light dependent stage) are used
• This takes place in reactions known collectively as the Calvin cycle
• Complex organic molecules are produced, including (but not limited to) carbohydrates, such as:
  • Starch (for storage)
  • Sucrose (for translocation around the plant)
  • Cellulose (for making cell walls)

Photosynthesis occurs in two, closely-linked stages: the light-dependent stage, which takes place in the thylakoids, and the light-independent stage, which takes place in the stroma