<P> When an electron rises to a higher energy level, there is a corresponding decrease in the reduction potential of the molecule in which the electron resides occurs . This means that the molecule has a greater tendency to donate electrons, which is key to the conversion of light energy to chemical energy . In green plants, the electron transport chain has many electron acceptors including phaeophytin, quinone, plastoquinone, cytochrome bf, and ferredoxin, which result finally in the reduced molecule NADPH and the storage of energy . The passage of the electron through the electron transport chain also results in the pumping of protons (hydrogen ions) from the chloroplast's stroma and into the lumen, resulting in a proton gradient across the thylakoid membrane that can be used to synthesise ATP using the ATP synthase molecule . Both the ATP and NADPH are used in the Calvin cycle to fix carbon dioxide into triose sugars . </P> <Table> <Tr> <Th_colspan="2"> Bacterial photosynthetic reaction center </Th> </Tr> <Tr> <Td_colspan="2"> Bacterial photosynthetic reaction center </Td> </Tr> <Tr> <Th_colspan="2"> Identifiers </Th> </Tr> <Tr> <Th> Symbol </Th> <Td> Photo_RC </Td> </Tr> <Tr> <Th> Pfam </Th> <Td> PF00124 </Td> </Tr> <Tr> <Th> InterPro </Th> <Td> IPR000484 </Td> </Tr> <Tr> <Th> PROSITE </Th> <Td> PDOC00217 </Td> </Tr> <Tr> <Th> SCOP </Th> <Td> 1prc </Td> </Tr> <Tr> <Th> SUPERFAMILY </Th> <Td> 1prc </Td> </Tr> <Tr> <Th> TCDB </Th> <Td> 3. E. 2 </Td> </Tr> <Tr> <Td_colspan="2"> <Table> <Tr> <Th_colspan="2"> (show) Available protein structures: </Th> </Tr> <Tr> <Th> Pfam </Th> <Td> structures </Td> </Tr> <Tr> <Th> PDB </Th> <Td> RCSB PDB; PDBe; PDBj </Td> </Tr> <Tr> <Th> PDBsum </Th> <Td> structure summary </Td> </Tr> </Table> </Td> </Tr> </Table> <Tr> <Th_colspan="2"> Bacterial photosynthetic reaction center </Th> </Tr> <Tr> <Td_colspan="2"> Bacterial photosynthetic reaction center </Td> </Tr>

What is the reaction center of photosystem ii