Photosynthesis

• Anaerobic


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• Light dependant reaction(1)

  • Photoionisation of pigment, loses excited e¯ that continues down transport chain releasing energy
  • Photolysis, 2H2O → 4H+ + 4e- + O2
  • e¯ replaced in pigment, protons help form ATP, O2 by product, e¯+ protons form NADP -> NADPH
  • Chemiosmosis, energy lost by e¯ pumps protons from thylakoid membrane to thylakoid space, bind to ATP synthase ADP + Pi -> ATP, and reforms NADP -> NADPH

  
• Light independant reaction (2)

  • Carbon fixation, CO2 + (5C) ribulose bisphosphate (RuBP) -> (6C) compound. This splits into two (3C) glycerate-3-phosphate (GP) molecules via enzyme ribulose bisphosphate carboxylase (rubisco).
  • GP reduced into triose phosphate (TP) via energy from hydrolysis of ATP. Also requires protons and electrons from NADPH, which regenerates NADP. NADP returns to the light-dependent reaction to be reduced again.
  • Most TP regenerates RuBP using ATP. Some TP can be used to make other organic molecules.

  
• NADPH

  • NAD(P)H and NAD(P), P for PLANT