Light dependent reaction

Light dependent reaction

1. Occurs in thylakoids

2. Involves capture of light

3. Oxidation and reduction- oxidation results in energy being given out, reduction- energy taken in

   • Oxidation loss of electrons  Reduction gain of electrons

4. Making ATP

   • Chlorophyll molecule absorbs light Energy
     • Boosts energy of of a pair of electrons -they are in an exited state
       • Electrons leave the chlorophyll molecule are taken up by an electron carrier
         • Chlorophyll molecules has been oxidised, the electron carrier reduced
           • The electrons are passed along a number of electron carriers in a series if oxidation-reduction reactions
             • Electron carrier form a transfer chain in the membrane of the thylakoids
               • Each new carrier- lower energy this lost energy is used to combine inorganic phosphate molecule with an ADP to make ATP
                 • ATP + H2O => ADP + Pi + energy

5. Photolysis of water

   • Lost Chlorophyll electrons are replaced
     • Provided from water molecules that are split using light energy
       • 2H2O=> 4H+ + 4e- + O2
         • H+ ions are taken up by a electron carrier called NADP And becomes reduced to NADPH which then enters the light- independent reaction
           • NADPH is important because it is a further potential source of chemical energy
         • O2 byproduct used in respiration or diffuses out of the leaf