BMB 211 Exam 4 Study Guide.docx

BMB 211 Exam 4 Study Guide.docx

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BMB 211 Exam 4 Study Guide Chapter 10: ETC and Oxidative Phosphorylation 1. What is electron transport and where does it occur? Electron Transport is when electrons from electron donors/acceptors are transferred via redox reactions, and are coupled with the movement of protons across the membrane. The ETC occurs in the intermembrane space of a mitochondria - Electron transport is EXERGONIC 2. Describe the prominent features of each complex in the ETC. Be able to trace the electrons through NADH and FADH 2 through formation of H 2 O. COMPLEX I = transfers electrons from NADH to Coenzyme Q (UQ UQH2) - NADH Dehydrogenase Complex 4 PROTONS PUMPED - Electrons come from glycolysis, citric acid cycle, and fatty acid oxidation COMPLEX II = mediates transfer of electrons from succinate to ubiquinone (UQ) - Succinate Dehydrogenase Complex (succinate fumarate) - Transfers electrons from FADH2 (from citric acid cycle) to Coenzyme Q (UQ UQH2) NO PROTONS PUMPED COMPLEX III = transfers electrons from reduced UQH2 to Cytochrome C - Cytochrome bc1 complex - Cytochrome C is a mobile protein that is able to carry electrons from one ETC complex to another – inhibited by high concentrations of ATP - ONE UQH2 transfers electrons through COMPLEX III to make TWO reduced cytochrome C proteins 4 PROTONS PUMPED COMPLEX IV = Catalyzes the final reduction of O2 to form H2O - Cytochrome Oxidase - Transfers electrons from TWO CYT C proteins to O2. - TWO protons from the matrix result in H2O - REACTION OCCURS TWICE TO COMPLETELY REDUCE O2 2 PROTONS PUMPED PER ROUND (4 TOTAL) - Complex IV is inhibited by high concentrations of ATP 3. How do the electron transport inhibitors discussed in class affect the ETC and ATP synthesis? Rotenone = blocks NADH dehydrogenase/inhibits COMPLEX I - Insecticide, possible link to Parkinson’s - Blocks electron transport and proton pumping at complex I Cyanide = inhibits cytochrome oxidase/inhibits COMPLEX IV - >98% inhibition of oxygen consumption - NO ATP GENERATED 4. How is the proton gradient formed? The electrons from NADH and FADH 2 flow through the electron transport chain in the inner mitochondrial membrane generating an H+ buildup in the inner membrane
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space. This proton gradient ( gradient of H+) flowing through the membrane enzyme complex ATP synthetase is the direct energy source for producing ATP. 5. Describe the chemiosmotic coupling theory Coupling of electron transfer to ATP synthesis is indirect due to a proton gradient - Spontaneous electron transfer through complexes I, III, and IV is coupled to non- spontaneous H + ejection from the mitochondrial matrix. H + ejection creates a membrane potential (negative in the matrix) and a pH gradient . - Non-spontaneous ATP synthesis is coupled to spontaneous H + transport into the matrix. The pH and electrical gradients created by respiration are together the driving force for H + uptake.
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