Bios 208 1st Edition Lecture 20 Outline of Last Lecture I. The Citric Acid CycleOutline of Current Lecture I. The Citric Acid CycleII. The Pathway of Electron TransportIII. Electron Transport Blocked by PoisonsIV. ATP Synthase ComplexCurrent LectureI. The Citric Acid CycleA. The next seven steps decompose the citrate back to oxaloacetate, making the process a cycleB. The NADH and FADH2 produced by the cycle relay electrons extracted from food to the electron transport chainC. Cycle of 8 reactions.D. Occurs in the mitochondrial matrixE. 2 turns per glucoseF. Net reaction per glucoseG. Citric Acid Cycle (a.k.a. Krebs cycle or TCA cycle)H. Reactants:a) 2 acetyl-CoAb) 2 ADPc) 6 NAD+d) 2 FADI. Products:a) CO2b) 2 ATPc) 6 NADHd) 2 FADH2J. 2 turns of the cycle per glucoseK. Reaction #1: Oxaloacetate (4C) + acetyl (2C) citrate (6C)L. oxidation reactions yield lots of reducing power:a) NADH +1FADH2 per acetyl-CoA;b) 6 NADH + 1 FADH2 per glucose)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.M. 1 ATP is made by SLP (involves a GTP intermediate)N. Following glycolysis and the citric acid cycle,O. NADH and FADH2 account for most of the energy extracted from foodP. These two electron carriers donate electrons to the electron transport chain, which powers ATP synthesis via oxidative phosphorylationQ. Making ATP (Oxidative Phosphorylation) is complicated. It requires:a) reducing power;b) a proton gradient;c) an electron transport chain;d) oxygene) many other factors. But, the ATP yield is HUGE.II. The Pathway of Electron TransportA. The electron transport chain is in the inner membrane (cristae) of the mitochondrionB. Most of the chain’s components are proteins, which exist in multi-protein complexesC. The carriers alternate reduced and oxidized states as they accept and donate electronsD. Electrons drop in free energy as they go down the chain and are finally passed to O2, forming H2OE. Electrons are transferred from NADH or FADH2 to the electron transport chainF. Electrons are passed through a number of proteins including cytochromes (each with an iron atom) to O2G. The electron transport chain generates no ATP directlyH. It breaks the large free-energy drop from food to O2 into smaller steps that release energy in manageable amountsI. Series of electron carriers: cytochromes (proteins with hemes) and inorganic carriers.J. Located in the inner mitochondrial membraneK. High energy electrons from NADH and FADH2 are transferred to the top of the chain.L. NADH + H+ NAD+ + 2 e- (delta G = -53 k/m; VERY exergonic)M. Electrons combine with O2; H2O is formed. O2 that we breathe is the final electron acceptor.III. Electron Transport blocked by poisonsA. Cyanide acts as a non-competitive inhibitor for the cytochrome a3 oxidase complex.B. This brings the electron transport chain to a halt, meaning the cell can get no energy outof respiration.C. CN Poisoning leads to unconsciousness and death.IV. ATP synthase complexA. The H+ gradient contains energy “proton motive force”.B. ATP Synthase is an enzyme complex located in the inner mito-membraneC. Movement of protons into the matrix (chemiosmosis) is exergonic. This movement is coupled to ATP synthesis, which is endergonic.D. Bigger H+ gradient more ATP madeE. Overall process is called oxidative
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