what is the structure of a photosystem?

Photosystems sit in the thylakoid membrane of chloroplasts. There job is to capture light energy and convert it into energy that can be used by the plant to eventually create ATP. Photosystems are made up a 3D protein structure with embedded pigments. The accessory pigments sit at the widest diameter setion of the cone, and the primary pigment reacton centre is found at the smallest diameter or 'spout' end of the cone. The primary pigment reaction centre houses a molecule of chlorophyll a, this is the molecule that is able to pass on, and convert the light energy - freeing up two electrons to enter the electron transport chain. This molecle of chlorophyll a has a certain obsoprtion spectrum, which means it can absorb the light energy most efficiently at certain wavelengths within the visible light sectrum. If this was the only pigment that the plant had, it would be restricted to only some of the visible wavelengths of light. That is where the accessory pigments come in. Molecules such as Chlorophyll b,Chlorophyll c, Fucoxanthin, Carotenoid, and Dinoxanthin are all accessor pigments. They have differen absorption spectra to chlorphyll a; therefore in housing these molecules in the photsystem, the plant is maximising its absorption capacity.