Light dependent reactions

• Oxidation

  • gain of oxygen
  • loss of hydrogen
  • loss of electrons
• Oxidation results in energy being given out
• Reduction

  • loss of oxygen
  • gain of hydrogen
  • gain of electrons
• Reduction results in energy being taken in
• light-dependent reaction occurs in the thylakoids
• Solar energy is used to

  • photophosphorylate
  • photolysis
• Making ATP

  1. A chlorophyll molecule absorbs light, boosts a pair of electrons to a higher energy level
  2. These "excited" electrons are taken up by electron carriers in a sequence of redox reactions
  3. Electrons are passed along the electron transport chain
  4. Energy released from the electrons moving is used to actively pump protons
• Chemiosmosis is the process of moving protons across the membrane of a cell
• Photolysis of water

  1. Electrons produced reduce the chlorophyll molecule restoring the electrons it has lost
  2. Oxygen produced is a by-product and can be used in respiration
  3. Protons are taken up by NADP along with electrons, which results in reduced NADP