BRAINCAKEThe Light-Dependent Reactions
The light-dependent reactions take place on the thylakoid membranes of the chloroplast. They use light energy to make ATP and reduced NADP for the light-independent reactions, and they release oxygen.
The main events:
1. Light absorption: light energy absorbed by the photosystems excites electrons in the reaction centre chlorophyll, which leave and pass to an electron acceptor.
2. Electron transport: the electrons pass along a chain of electron carriers in the thylakoid membrane, losing energy in a series of redox reactions.
3. Chemiosmosis: this energy pumps protons into the thylakoid space. Protons flow back into the stroma through ATP synthase, and ADP + Pi → ATP. Making ATP using light energy is called photophosphorylation.
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More in Photosynthesis
- Chlorophyll
- Absorption Spectrum Chlorophyll
- Chromatography
- Photosystems
- Cyclic Photophosphorylation
- Non-Cyclic Photophosphorylation
- The Light-Independent Stage
- The Calvin Cycle
All 20 lessons in Photosynthesis · All Edexcel A-level Biology topics