BIOL 1441 1st Edition Lecture 16 Outline of Last Lecture I Allosteric Regulation of Enzymes II Cooperativity III Feedback inhibition IV Photosynthesis respiration V Cellular respiration VI Redox reactions VII Antioxidants VIII Relocation of electrons IX Electron transport chain Outline of Current Lecture I Substrate level phosphorylation II Glycolysis III Citric acid cycle IV Electron transport chain V Cellular Respiration VI Chemiosmosis VII ATP synthase multisubunit complex Current Lecture 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 I II Substrate Level Phosphorylation a ATP is made by direct enzymatic transfer of phosphate group from substrate to ADP rather than an inorganic phosphate Pi b Only a couple ATP made in this process Glycolysis a Glyco sugar Lysis split splitting sugar b Glucose 6 carbon sugar i Two 3 carbon sugars PYRUVATE c Happens in cytosol d Have to invest 2 ATP to make more e Makes 4 ATP f Net 2 ATP g NO CO2 RELEASED h Happens whether oxygen is present or not i If oxygen is present goes into citric acid cycle j If oxygen isn t present goes into fermentation k 10 steps i taking glucose from low energy to high energy by tagging a phosphate onto it 1 Makes glucose 6 phosphate ii Rearrange molecules structures not important iii Adding another phosphate higher energy 1 Enzyme phosphofructo kinase 2 PFK controls rate of respiration allosteric enzyme iv Chop 6 carbons into two 3 carbons v Glyceraldehyde 3 phosphate G3P is made 1 Enzyme isomerase vi G3P is oxidized vii MAKES ATP viii Rearranging not important ix Rearranging not important x Makes pyruvate 1 Made some ATP 2 MOST ENERGY STILL IN PYRUVATE l Glycolysis Overview i Used 2 ATP ii Made 4 ATP iii Net gain 2 ATP iv Made 2 NADH used in ETC to generate more ATP v Oxygen present citric acid cycle vi No oxygen fermentation vii REDUCED State 1 Glucose REDUCING AGENT III 2 NADH viii OXIDIZED State 1 Pyruvate 2 NAD OXIDIZING AGENT ix Oxidize glucose into pyruvate remove electrons x Reduce NAD into NADH add electrons xi OXYGEN NOT USED ANYWHERE xii PURPOSE OXIDIZE GLUCOSE Citric Acid Cycle Kreb s Cycle a Cycle completes oxidation of organic molecules b Before the citric acid cycle can begin pyruvate must be converted to acetyl CoA c OXIDIZES PYRUVATE d Takes place within the mitochondrial matrix e All enzymes are embedded in matrix except 1 in step 6 f Cycle oxidizes organic fuel derived from pyruvate generating one ATP 3 NADH and 1 FADH2 per turn i Remember 1 molecule of glucose 2 turns g NADH FADH2 shuttle high energy electrons to electron transport chain i FAD flavin adenine dinucleotide derived from B vitamin riboflavin electron acceptor h PYRUVATE DOES NOT GO INTO THIS CYCLE ACETYL COA DOES i 8 steps each catalyzed by a different enzyme i Acetyl CoA combines with oxaloacetate to form citrate ii Step 2 unimportant iii Isocitrate is oxidized NAD is reduced to NADH CO2 is removed iv CO2 is removed NAD is reduced to NADH v Phosphate is transferred to GDP forming GTP GTP generates ATP substrate level phosphorylation vi FADH2 is formed vii Step 7 not important viii Malate is oxidized into oxaloacetate NAD reduced to NADH j Citric Acid Cycle Overview i I turn generates 1 ATP 3 NADH 1 FADH2 1 1 molecule glucose 2 ATP 6 NADH 2 FADH2 ii NADH and FADH2 supply energy needed to make ATP by transferring electrons to electron transport chain iii Completing the oxidation of pyruvate iv REDUCED State 1 NADH 2 FADH2 3 Reducing agents v OXIDIZED State 1 NAD IV V VI VII 2 FAD 3 Oxidizing agents Electron transport chain a Occurs in the inner membrane of mitochondria b Most components are multiprotein complexes I IV c Carriers alternate reduced oxidized states as they accept donate electrons d Electrons drop in free energy as they go down the chain and are finally passed to O2 forming water i Moving HIGH energy LOW energy e Each component of the chain becomes reduced when it accepts electrons from its uphill neighbor f Becomes oxidized again as it passes the electron downhill g SETS UP H GRADIENT h Does not produce any ATP directly i Function is to break a large free energy drop into a series of small steps that release energy into manageable amounts sets up H gradient j Chemiosmosis couples this mechanism to ATP synthesis Cellular Respiration a Importance of oxygen b Without electronegative O2 to pull electrons down ETC oxidative phosphorylation would stop Chemiosmosis a Use of energy in H gradient to drive cellular work b Electron transfer in ETC causes proteins to pump H from the mitochondrial matrix into the intermembrane space c LOW H CONCENTRATION IN MATRIX HIGHER pH d HIGH H CONCENTRATION IN INTERMEMBRANE SPACE LOWER pH e H then moves back across the membrane diffusion passing through channels in ATP synthase f ATP synthase uses the exergonic flow of H to drive phosphorylation of ADP g ATP synthase located on inner membrane enzyme actually makes ATP from ADP and Pi h ATP synthase uses energy from proton gradient to power ATP synthesis i Power source for ATP synthase is the difference in the concentration of H on opposite sides of the inner membrane membrane potential ATP synthase is multisubunit complex a Rotor within the membrane spins as shown when H flows past it down the H gradient b Stator anchored in the membrane holds the knob stationary c Rod extending into the knob also spins activating catalytic sites in the knob d Knob join inorganic phosphate to ADP to make ATP