<P> Plastoquinone, in turn, transfers electrons to cyt, which feeds them into PS I . </P> <P> The step H O → P680 is performed by a poorly understood structure embedded within PS II called the water - splitting complex or the oxygen - evolving complex . It catalyzes a reaction that splits water into electrons, protons and oxygen: </P> <P> The actual steps of the above reaction are running in the following way (Dolai's diagram of S - states): (I) 2H2O (monoxide) (II) OH . H2O (hydroxide) (III) H2O2 (peroxide) (IV) HO2 (super oxide) (V) O2 (di - oxygen). (Dolai's mechanism) </P> <P> The electrons are transferred to special chlorophyll molecules (embedded in PS II) that are promoted to a higher - energy state by the energy of photons . </P>

Where do light dependent reactions occur in photosynthetic prokaryotes