Photosynthesis light independent stage

Photosynthesis light independent stage

1. Please go through the Light Dependent stage before this one as the light-independent stage relies on that stage and without reading it you won't know why.

2. Cycle itself

   • Intermediate 6 carbon molecule formed
     • This molecule breaks down very quickly however
     • 2 Glycerate 3-phosphate molecules form or GP
       • Substances used
         • 12 NADPH
           • 12 NADP
         • 12 ATP
           • 12ADP + 2Pi
         • 2 Triose Phosphate
           • Substances used
             • ATP
               • ADP + Pi
             • RuBP or Ribulose Bisphosphate
               • Carbon is fixed here
                 • Uses the Enzyme Rubisco. Rubisco however is inhibited by oxygen
             • This also comes from the light dependent reaction
           • May be called galp as well
           • For every 6 triose phosphates made 1 goes to make glucose and more complex molecules
         • There are 2 used because there are 2 molecules of GP. Both of these products come from the light dependent reaction.
           • The atp is used for the energy
       • This GP can be used to form Amino Acids and lipids
   • The cycle is labelled in purple whereas the explanation is labeled around in different colours corresponding to each section

3. The cycle shown in purple is called C3 photosynthesis

   • C4 photosynthesis uses this reaction but changes where it happens and the conditions
     • C4 uses PEP carboxylase to fix Carbon dioxide to PEP to form malate. This malate is then moved to bundle sheath cells. Then it is decarboxylated and the normal calvin cycle takes place. This process increases carbon dioxide concentration massively and so significantly reduces the effect of oxygen inhibition on Rubisco.
       • This process, however, is only worth doing when carbon dioxide concentration is the limiting factor for photosynthesis