BIOL 111 301 1st Edition Lecture 11Outline of Last Lecture I. Review quizII. GlycolysisIII. Junction ReactionsIV. Overview of the citric acid cycleV. Mitochondrial structureVI. Oxidative phosphorylationVII. How much energy (# ATP) was harvest4ed from glucose?Outline of Current LectureI. Review/PreviewII. Nature Of Light III. PigmentsIV. What happens to the absorbed light?V. Light Reactions: converting solar energy to chemical energyVI. How much energy did we harvest from the sun?Current Lecture- Review/Previewo Energy Mattero Redox rxnso Laws of Thermodynamicso Kinetic vs. Potential energy o Follow carbons o Follow electronso Carbon cycleo Electron transport chain & chemiosmosiso ATP synthase- Nature Of Light o Form of energy on electromagnetic spectrum from 380-750 nmo Both particle and wave propertieso Wavelength = distance between crestso Energy of light = 1/wavelength, so more E, from shorter waveo Photon = discrete light particles- Pigmentso Substances that selectively absorb visible lighto Chlorophyll ao Chlorophyll bo Carotenoids- What happens to the absorbed light?o Photon hits pigment, e- excited, then falls (Fig 2.8)o Dissipation (Fig 10.11) Emit photon of light: Fluorescence Emit heat Transfer e- to other pigment: Resonance transfer- Light Reactions: converting solar energy to chemical energyo 1) Light harvesting complexes (PSII and PSI) Within thylakoid membrane Contain proteins and few 100 pigments Outer pigments absorb purple wavelengths, inner absorb red Excited e- energy transferred via resonance transfer from high E low Eo 2) Linear electron flow—produces ATP and NADPH Photons excite e- in pigments and energy transferred to pair of chlorophyll a= P680, donates e- to a primary acceptor in the reaction complex P680 “strongest oxidizing agent in the world” Rips 2 e- from WATER (NOT light!) Water donates 2 e- to excited P680+, one by one Photons excite e- in pigments and energy transferred to P680 Water donates 2 e- to excited P680+, one by one E- “fall down” e- transport chain via redox rxns to PSI e- acceptor P700 Additional photons excite these e- Photons excite e- in pigments and energy transferred to P680 Water donates 2 e- to excited P680+, one by one E- “fall down” e- transport chain via redox rxns to PSI e- acceptor P700 Additional photons excite these e-o 3) Cyclic electron flow—Produces ONLY ATP Use PSI Fd cytochrome complex Creates proton gradient ATP synthase- How much energy did we harvest from the sun?o In Linear E- Transport, 4 photons will: Oxidize 1 H2O ½ O2 + 2H+ + 2e- Transport 2 e- from H2O NADP+ Reduce NADP+ NADPH to Calvin cycle Generate H+ in thylakoid space:- 2 H+ (from H2O)- 4 H+ (pumped by e- transport) Produce 1.5 ATP
View Full Document