File:Fpls-02-00028-g004.png

English: A simplified Z-scheme representing the linear (black solid arrows) and a cyclic (black dashed arrow) electron transport in cyanobacteria. Straight yellow arrows are for excitation of RC Chl a molecules that leads to electrons in the ground state to be raised into higher (singlet) excited state (P680 in PSII and P700 in PSI) in response to the absorption of light quanta (wavy arrows) via the antenna system (see Figure 2). Other abbreviations: Em (eV), redox potential at pH 7 (in electron volts); e−, electron; PQ, plastoquinone; Cyt b6f, cytochrome b6f complex; Cyt c553, cytochrome c553; PC, plastocyanin (for details on Cyt c553 and PC, see Zhang et al., 1992); the numbers 680 and 700 are the wavelengths of the absorption maxima, in the first excited state, for the Chl a RC molecules in PSII and PSI, respectively. Modified and adapted from Govindjee et al. (2010) and Shevela and Messinger  (2011).