Photosynthesis Light Reaction Electron Transport Chain E T

The Light Reaction • Takes place in the Thylakoid membrane § Also called the

Outside Thylakoid = Stroma H+ H+ H-O-H H+ H+ H+ concentration is at equilibrium

Outside Thylakoid = Stroma 1. Start of Light Reaction- Light is absorbed by clorophyll.

Outside Thylakoid = Stroma 2. Light energy is taken by Clorophyll and WATER SPLITTING

Outside Thylakoid = Stroma 3. The electrons will then move into the ETC. They

Outside Thylakoid = Stroma 4. At this point the electrons have no more energy.

Outside Thylakoid = Stroma 5. A Concentration Gradient has been created. LOW Concentration H+

Outside Thylakoid = Stroma 6. As the H+ ions flow through the ATP Synthase,

Outside Thylakoid = Stroma 7. The last step is to remove the electrons so

Summary § The ETC = the Light Reaction § It takes place in the

ETC Reactants and Products § Reactants needed § Light § Water (H-O-H) § The

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Photosynthesis: Light Reaction Electron Transport Chain (E. T. C. )

The Light Reaction • Takes place in the Thylakoid membrane § Also called the Electron Transport Chain. § Requires: § Light § Water § ADP § NADP+ and H + § Produces: § ATP § Oxygen (O 2) § NADPH

Outside Thylakoid = Stroma H+ H+ H-O-H H+ H+ H+ concentration is at equilibrium H+ H-O-H H+ H+ Inside Thylakoid H+

Outside Thylakoid = Stroma 1. Start of Light Reaction- Light is absorbed by clorophyll. H+ H+ H+ H-O-H H+ H+ H+ Inside Thylakoid H+ H+

Outside Thylakoid = Stroma 2. Light energy is taken by Clorophyll and WATER SPLITTING ENZYME TO split water. H+ H+ H-O-H + H H-O-H + O 2 + H H H+ H+ Oxygen, more Hydrogen Ions are made AND 2 ELECTRONS ARE RELEASED H+ H+ Inside Thylakoid H+ H+

Outside Thylakoid = Stroma 3. The electrons will then move into the ETC. They go to each ELECTRON ACCEPTOR in the chain. H+ H+ H+ H+ H+ At each electron acceptor, H+ are pumped IN TO the Thylakoid. Inside Thylakoid H+ H+

Outside Thylakoid = Stroma 4. At this point the electrons have no more energy. H+ H+ H+ H+ H+ More light is absorbed so the electrons can continue down the ETC. Inside Thylakoid H+ H+ H+

Outside Thylakoid = Stroma 5. A Concentration Gradient has been created. LOW Concentration H+ H+ H+ H+ H+ HIGH Concentration + H H+ The H+ ions flow through the ATP SYNTHASE. H+ Inside Thylakoid H+

Outside Thylakoid = Stroma 6. As the H+ ions flow through the ATP Synthase, the H ATP Synthase takes ADP and turns it into ATP. + H+ H+ H+ H+ P P P A H+ This is facilitated diffusion. Inside Thylakoid H+ H+ Energy from H+ movement used to make ATP

Outside Thylakoid = Stroma 7. The last step is to remove the electrons so the ETC can continue to function. A molecule called NADP+ bonds with an H+ to remove the electrons. H+ H+ H+ H + + NADPH H+ H+ Inside Thylakoid H+

Summary § The ETC = the Light Reaction § It takes place in the Thylakoid membrane. § It captures light energy, and uses that energy to move electrons down the chain. § Each Electron Acceptor moves H+’s INTO the thylakoid creating a concentration gradient. § THIS IS ACTIVE TRANSPORT § The H+’s then flow through the ATP Synthase, which creates ATP. § This is Facilitated Diffusion (Passive Transport) § The electrons are removed from the ETC by NADP+ and H+ creating NADPH

ETC Reactants and Products § Reactants needed § Light § Water (H-O-H) § The water is split producing oxygen, H+’s, and electrons. § ADP (turned into ATP) § NADP+ and H+ § Removes electrons from ETC. § Products § Oxygen (released into atmosphere) § ATP = used in Dark Reaction § NADPH = used in Dark Reaction