Each photosystem contains many proteins and pigment molecules embedded in the thylakoid
membrane. The reaction center of each photosystem is a complex of proteins, electrontransporting
cofactors, and two chlorophyll a molecules called the special pair. The
absorption maximum of the special pair of PSI is 700 nm; these pigments are called P700. In
PSII, the special pair pigments absorb light maximally at 680 nm and are called P680.
In PSI, various other pigments are bound to the reaction center of
PSI. In PSII, they are part of an antenna complex. These pigments
can absorb light and transfer the energy to the adjacent pigment
molecules. The energy eventually reaches the special-pair chlorophyll
molecules.