Energy transferring reactions The pigment molecules that capture energy from the sun are arranged in the thylakoid membranes of the chloroplasts in structurally separate units called photosystems . Hundreds of systems are present in each thylakoid. Each photosystem has a light collecting array of 200–300 molecules, the antenna complex , not unlike a satellite dish, which collects and focuses the photons into the reaction center where energy processing begins. The photons move from antenna molecule to antenna molecule without an energy loss, a resonance energy transfer. There are two kinds of photosystems, Photosystem I (PsI) and Photosystem II (PsII) . In the reaction center of PsI the light-absorbing pigment is a specialized chlorophyll a molecule that absorbs red light of 700 nanometer wavelength most efficiently, hence the designation P700 . PsII
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This note was uploaded on 11/14/2011 for the course BIO 1421 taught by Professor Farr during the Fall '08 term at Texas State.