Photosynthesis Light Reaction

The light-dependent reactions of photosynthesis occur in the thylakoid membranes of chloroplasts. The process involves:

1. Light absorption: Chlorophyll and other pigments in photosystems capture light energy.
2. Electron excitation: Light energy excites electrons in photosystem II.
3. Electron transport chain: Excited electrons pass through a series of electron carriers.
4. ATP production: Energy from electron flow is used to pump protons, creating a gradient that drives ATP synthesis.
5. NADPH formation: Electrons are ultimately transferred to NADP+ to form NADPH.
6. Water splitting: Electrons lost from photosystem II are replaced by splitting water, releasing oxygen.

These reactions produce ATP and NADPH, which are then used in the Calvin cycle for carbon fixation.