Bios 208 1st Edition Lecture 21 Outline of Last Lecture I. The Citric Acid CycleII. The Pathway of Electron TransportIII. Electron Transport Blocked by PoisonsIV. ATP Synthase ComplexOutline of Current Lecture I. Formation of a proton [H +] gradientII. An Accounting of ATP Production by Cellular RespirationIII. Anaerobic bacteriaIV. Types of FermentationV. The Evolutionary Significance of GlycolysisCurrent LectureI. Formation of a proton [H +] gradientA. e- carriers form 3 complexes (I, III, and IV).B. As e- pass through each complex (exergonic), protons are pumped across the inner mitochondrial membrane (endergonic).C. Therefore, e transport (NADH O2) leads to the formation of a H+ gradient.D. [H+] is 10x – 100x higher in the intermembrane space than in the matrix (i.e.,1 – 2 pH units lower).E. The energy stored in a H+ gradient across a membrane couples the redox reactions of theelectron transport chain to ATP synthesisF. The H+ gradient is referred to as a proton motive force, emphasizing its capacity to do workII. An Accounting of ATP Production by Cellular RespirationA. During cellular respiration, most energy flows in this sequence: glucose > NADH > electron transport chain > proton-motive force > ATPB. About 34% of the energy in a glucose molecule is transferred toC. There are several reasons why the number of ATP is not known exactly…D. Electron transport chain reactions and phosphorylation to make ATP are not directly coupled.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.E. Number of protons passing through ATP synthase to make ATP is about 4 per ATP generated, but is slightly variable.F. Most cellular respiration requires O2 to produce ATP.G. Without O2, the electron transport chain will cease to operate.H. In that case, glycolysis couples with fermentation or anaerobic respiration to produce ATP.I. Anaerobic respiration uses an electron transport chain with a final electron acceptor other than O2, for example sulfate.J. Fermentation uses substrate-level phosphorylation instead of an electron transport chain to generate ATP.III. Anaerobic bacteriaCH4 + SO42– → HCO3 – + HS– + H2OA. Anaerobic bacteria can use sulphate to oxidize methane as a carbon source.B. Such bacteria form black sludge of metal sulfides at the bottom of some ponds.C. Desulfovibrio vulgaris is an example of anaerobic bacteria.IV. Types of FermentationA. Fermentation consists of glycolysis plus reactions that regenerate NAD+, which can be reused by glycolysisB. Two common types are alcohol fermentation and lactic acid fermentationC. In alcohol fermentation, pyruvate is converted to ethanol in two steps, with the first releasing CO2D. Alcohol fermentation by yeast is used in brewing, winemaking, and bakingE. In lactic acid fermentation, pyruvate is reduced to NADH, forming lactate as an end product, with no release of CO2F. Lactic acid fermentation by some fungi and bacteria is used to make cheese and yogurtG. Human muscle cells use lactic acid fermentation to generate ATP when O2 is scarceH. Obligate anaerobes carry out fermentation or anaerobic respiration and cannot survive in the presence of O2I. Yeast and many bacteria are facultative anaerobes, meaning that they can survive using either fermentation or cellular respirationJ. In a facultative anaerobe, pyruvate is a fork in the metabolic road that leads to two alternative catabolic routesV. The Evolutionary Significance of GlycolysisA. Ancient prokaryotes are thought to have used glycolysis long before there was oxygen in the atmosphere.B. Very little O2 was available in the atmosphere until about 2.7 billion years ago, so early prokaryotes likely used only glycolysis to generate ATP.C. Where did oxygen come from?D. Glycolysis is a very ancient process.E. Glycolysis and the citric acid cycle connect to many other metabolic pathways.F. Glycolysis and the citric acid cycle are major intersections to various catabolic and anabolic
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