Photosynthesis called P680. The source of electrons for photosynthesis in green plants and cyanobacteria is water. Two water molecules are oxidized by four successive charge-separation reactions by photosystem II to yield a molecule of diatomic oxygen and four hydrogen ions. The electrons yielded are transferred to a redox-active tyrosine residue that then reduces the oxidized P680. This resets the ability of P680 to absorb another photon and release another photo-dissociated electron. The oxidation of water is catalyzed in photosystem II by a redox-active structure that contains four manganese ions and a calcium ion; this oxygen-evolving complex binds two water molecules and
What You Need (The Twilight Zone) What You Need (The Twilight Zone) "What You Need" is episode 12 of the American television anthology series "The Twilight Zone". It is based on the short story of the same name by Lewis Padgett (Henry Kuttner and C. L. Moore). Pedott , a peddler, has the curious ability to give people exactly what they need before they need it. He enters a coffee shop where he first gives a woman a vial of cleaner. Then he gives a down-on-his-luck ex-baseball player a bus ticket to Scranton, Pennsylvania. Moments later, the ball player receives a phone call at the cafe