The three parts of a photosystem are:
1. Light-harvesting complexes: consists of various pigment molecules bound to proteins. It captures light energy and transfers it to reaction-center pigments in a photosystem.
2. Reaction-center complex: uses the energy from light to boost the electrons to a higher energy level and to transfer it to the molecule PEA(primary electron acceptor.)
3. Primary electron acceptor: A specialized molecule that shares the reaction-center complex with a pair of chlorophyll (a) molecules and accepets electrons from them.
Overview of how a photosystem works:
When a photon strikes a pigment molecule in light-harvesting complex, the energy is passed from molecule to molecule until it reaches the reaction-center complex. Here, an excited electron from the special pair of chlorophyll (a) molecule is transferred to the primary electron acceptor.