A small protein transports electrons between the two photosystems involved in plant photosynthesis
The emergence of oxygenic photosynthesis made it possible for complex multicellular life-forms to evolve on Earth. By utilizing solar energy to turn carbon dioxide into sugars, while also generating molecular oxygen from water, photosynthesis provides the basis for both plant and animal life. These two processes are carried out by distinct, but functionally connected complexes called photosystems I and II (PSI and PSII). In cyanobacteria, algae and plants, these photosystems—all of which employ chlorophyll pigments to capture light energy—are embedded in specialized lipid membranes called thylakoids. Moreover, the thylakoids that contain PS I and PSII differ in their organization, which effectively enables the two systems to convert light of different wavelengths into chemical energy.