Light reactions

• Photosynthesis


  Not one chemical reaction

  
• Photosynthesis


  1. General equation

  2. Two stage process

  3. Stage one: Light (dependent) reactions

  4. Stage two: Sugar making

  
• Light reactions


  • Require light
  • Occur in thylakoid discs
  • Main purpose is to make ATP and NADPH
• Chloroplast structure: Stroma, thylakoid discs, grana
• Thylakoid disc membrane


  • Pigments clustered in photosystems
  • Chlorophyll a is primary pigment
  • Accessory pigments capture other wavelengths
  • Electron transport chain connects photosystems

  
• Oxidation


  Loss of electrons
• Reduction


  Gain of electrons
• Light reactions


  1. Oxidation of photosystem II

  2. Photolysis of water

  3. Electron transport chain

  4. ATP synthesis via chemiosmosis

  5. Reduction of NADP+

  
• Light reactions produce ATP and NADPH
• Light reactions also produce oxygen as waste