The Light Reactions Broad daylight is cool Light Energy Light reactions are the energy transduction reactions. Light reactions take place on the actual thylakoid membrane. Light reactions contain photosystems I, II, or both. The two systems are compared in the following table. Photosystems I and II are both used in this process.
Water is split into oxygen, protons, and electrons.
The electrons from water are used for chlorophyll molecules that have donated electrons. The electrons pass through electron carriers which are redox carriers. They are transferred to reversal places before finally reaching the reaction center again. The electron transport chain creates a proton gradient to provide energy for ATP synthesis. These reactions can take place in the dark or in the light.