Light-dependent reactions

The photosynthetic reactions that convert light energy into chemical energy stored in ATP and NADPH. In oxygenic photosynthesis, they split water and release oxygen.

Photosystem II: A light-absorbing protein complex that extracts electrons from water and transfers them into the photosynthetic electron-transport chain. It begins oxygenic electron flow by replacing excited electrons with electrons from water.
Thylakoid: A flattened membrane sac in chloroplasts and cyanobacteria where oxygenic photosynthesis captures light energy. The reactions occur in its membrane and use the space across it to build a proton gradient.
NADPH: A reduced electron carrier that supplies high-energy electrons for biosynthesis and other cellular reactions. The reactions produce NADPH for carbon fixation and other chloroplast processes.
Anoxygenic photosynthesis: Photosynthesis that uses electron donors other than water and therefore does not release oxygen. It shows that light-driven electron transport need not split water or produce oxygen.
Photosystem I: A light-absorbing protein complex that re-energizes electrons and helps reduce NADP⁺ to NADPH. It supplies the high-energy electrons used to make NADPH.
Chlorophyll: A family of light-absorbing pigments that captures energy for photosynthesis, especially from blue and red wavelengths. Its excitation initiates the energy transfers within the photosystems.
Photophosphorylation: The light-driven synthesis of ATP through a proton gradient generated by photosynthetic electron transport. It names the ATP-producing process carried out by these reactions.
Chemiosmosis: The use of an ion gradient across a membrane to drive cellular work, including ATP synthesis. It is the broader mechanism behind ATP production in the thylakoid.
Oxygen-evolving complex: A manganese-calcium cluster in photosystem II that extracts electrons from water and releases molecular oxygen. It performs the water-splitting step that releases oxygen.
Light-harvesting complex: A pigment-protein assembly that absorbs light and transfers excitation energy to a photosynthetic reaction center. It broadens the wavelengths captured before energy reaches a reaction center.

Linked from 2 pages

PhotosynthesisBroader topic: They convert captured light into the chemical energy and reducing power used to fix carbon.