BIOL 120 1st Edition Lecture 14 Outline of Last Lecture I Electron Transport Chain II Anaerobic vs Aerobic III Photosynthesis Overview Outline of Current Lecture I Photosystems II Non cyclic III Cyclic IV Calvin Cycle V Photorespiration Current Lecture I Photosystems A Photosystem a complex formed from chlorophyll molecules working together in groups B Has two major elements along with proteins that capture and process electrons 1 Antenna complex a also known as light harvesting complex b captures photons and channels them to reaction center chlorophylls c In chloroplast these are a web of chlorophyll molecules held together in the thylakoid membrane by a matrix of proteins These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute 2 Reaction center a This is the transmembrane protein pigment complex b when a chlorophyll absorbs a photon of light an electron is excited to a higher energy level C Photosystem II 1 Has a core of ten transmembrane protein subunits 2 Has two P680 chlorophyll 3 Reaction center contains 4 manganese atoms needed for oxidation of water 4 Has b6 f complex Proton pump embedded in thylakoid membrane D Photosystem I 1 reaction center has 12 14 protein subunits 2 Has two P700 chlorophyll 3 accepts electrons to make NADP into NADPH E Chemiosmosis 1 used to synthesis ATP 2 Chrlroplast has ATP synthase enzymes in the thylakoid membrane that allows protons back into the stroma a the stroma has enzymes that catalyze the reaction of carbon fixation Calvin Cycle II Non Cyclic A also known as Z pathways B source of electrons is from photolysis of water C Generates NADPH oxygen and ATP D Has 4 steps 1 Primary photoevent a photon of light is captured by a pigment molecule 2 Charge separation a energy is transferred to the reaction center and an excited electron goes to an acceptor 3 Electron Transport a electrons move through carriers and reduce NADP to NADPH 4 Chemiossmosis a Makes ATP E Require two connected photosystems 1 uses both photosystem I and II 2 Photosystem II P680 pool of electrons coming from the photolysis of water a Energy level of protons goes up and then transferred to electron acceptor because it is too much and keeps being transferred until I energy slowly decreasing until reaches I and process continues III Cyclic A only uses Photosystem II B Generates ATP through the electron transport anoxygenic doesn t make oxygen IV Calvin Cycle A also called C3 pathways of photosynthesis B Key step is attachment of CO2 to RuBP to form PGA C Uses rubisco to react with carbon and oxygen a carboxylase fixing carbon b oxygenase fixing oxygen c inefficient because it catalyzes both carbon and oxygen D Light reaction provides ATP to run the Calvin Cycle which makes glucose fixes CO2 and regenerates RuBP E Three Phases a Carbon fixation RuBP 5C CO2 PGA 3C b Reduction PGA is reduced to G3P which is used to synthesis glucose not a direct product of Calvin Cycle i extra sugar created is stored as starch c Regeration of RuBP V Photorespiration A Carboxylation carboxylase favored under normal conditions B Photorespiration oxygenase favored when stoma are closed in hot conditions C Stomata 1 openings in leaves that control gas exchange 2 guard cells 2 CO2 concentration is low during photosynthesis let CO2 in a needed because the Calvin Cycle is constantly using up CO2