BIOL 1411 1st Edition Lecture 12 Outline of Last Lecture I Enzymatic inhibition II Bioenergetics Outline of Current Lecture I Bioenergetics a Pyruvate Oxidation b Citric Acid Cycle c Oxidative Phosphorylation d Chemiosmosis II Fermentation a Lactic Acid b Alcohol fermentation Lecture Glycolysis Step 6 redox reaction Pyruvate Oxidation also called decarboxylation o Links glycolysis in cytoplasm and the citric acid cycle in mitochondria o Occurs in the liquid mitochondrial matrix Pyruvate 3C acetate C2 CO2 o CO2 released as waste o NAD is reduced to NADH capturing energy o Some energy is stored by combining acetate and Coenzyme A to for acetyl CoA Citric Acid Cycle Krebs o Eight reactions that begin with acetyl CoA o In a steady state the concentrations of the intermediates don t change o Inputs acetyl CoA electron carriers NAD and FAD and GDP Energy released is captured by the electron carriers and GDP o Outputs CO2 reduced electron carriers NADH FADH2 and GTP which converts ADP to ATP o Strip energy off of citrate o Whenever there is a decrease in C CO2 is released Summary to this point o Glucose 2 pyruvate 6 CO2 o 4 ATP made 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 o 10 NADH 2 FADH2 holds energy in the electrons o re oxidation is going to be linked to lots more ATP oxidative phosphorylation Oxidative Phosphorylation involves proteins and elctron carrier molecules imbedded in the mitochondrial inner membrane cristae o 2 interconnected stages Electron transport chain e from NADH and FADH2 pass through a respiratory chain of inner membrane carriers 4 protein complexes I II III IV Ubiquinone Q Cytochrome c Oxygen is the final electron acceptor ETC makes no ATP directly o Chemiosmosis Protons H diffuse back into the mitochondria through ATP synthase a channel protein Diffusion is coupled to ATP synthesis Energy is used to transport protons against their concentration gradient Protons accumulate in the inter membrane space Creates charge difference across membrane potential energy This Proton motive force later drives protons back across membrane The protons move through the ATP synthase channel providing energy to phosphorylate ADP ATP synthesis is favored over ATP hydrolysis o ATP leaves the mitochondria once made keeping the concentration low ATP synthase a molecular machine o H flows rom inter membrane space through synthase to matrix o Flow rotates rotor driving conformation changes in catalytic knob subunits o Shape changes force condensation of ADP Pi ATP o Proton gradient ATP Generation in absence of oxygen Fermentation o Lactic acid o Ethanol Anaerobic respiration respiratory chains that have a different final e acceptor nitrate sulfate sulfur metal ions Lactic Acid o Occurs in microorganisms some muscle cells o Pyruvate is the electron acceptor becomes reduced o Oxidizes NADH back to NAD so more glycolysis can occur o Lactate is the product and can build up o No additional ATP is made Alcohol fermentation o Yeasts and some plant cells o Requires 2 enzymes to metabolize pyruvate to ethanol o CO2 is a waste product o The intermediate acetaldehyde is reduced by NADH H producing NAD and glycolysis continues Cellular respiration yields more energy than fermentation o Neither aerobic respiration or fermentation capture all of the energy released by glucose oxidation o 32 ATP for cellular respiration o Only get 2 ATP for fermentation o AR is 41 efficient rest lost to heat Metabolic pathways interrelated and regulated o An interexchange of molecules occurs between metabolic pathways o Pathways are interrelated by shared substances Catabolism and anabolism are integrated o Negative and positive feedback controls o Allosteric inhibitors act on key enzymes Concentrations of biochemical molecules remain constant glucose concentration in blood Reoccurring themes of living systems
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