BIOL 1441 1st Edition Lecture 16 Outline of Last Lecture I. Allosteric Regulation of EnzymesII. Cooperativity III. Feedback inhibition IV. Photosynthesis/respirationV. Cellular respirationVI. Redox reactionsVII. AntioxidantsVIII. Relocation of electronsIX. Electron transport chainOutline of Current Lecture I. Substrate level phosphorylationII. GlycolysisIII. Citric acid cycleIV. Electron transport chainV. Cellular RespirationVI. ChemiosmosisVII. ATP synthase multisubunit complexCurrent LectureThese 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. Substrate Level Phosphorylationa. 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 processII. Glycolysisa. Glyco “sugar” Lysis “split” : splitting sugarb. Glucose 6-carbon sugari. Two 3-carbon sugars- PYRUVATEc. Happens in cytosold. Have to invest 2 ATP to make moree. Makes 4 ATP f. Net 2 ATPg. NO CO2 RELEASEDh. Happens whether oxygen is present or noti. If oxygen is present-goes into citric acid cyclej. If oxygen isn’t present-goes into fermentationk. 10 steps:i. taking glucose from low energy to high energy by tagging a phosphate onto it1. Makes glucose-6-phosphateii. Rearrange molecules/structures(not important)iii. Adding another phosphate= higher energy.1. Enzyme= phosphofructo-kinase2. PFK controls rate of respiration (allosteric enzyme)iv. Chop 6-carbons into two 3-carbonsv. Glyceraldehyde-3-phosphate- G3P is made1. Enzyme=isomerasevi. G3P is oxidizedvii. MAKES ATPviii. Rearranging (not important)ix. Rearranging (not important)x. Makes pyruvate1. Made some ATP2. MOST ENERGY STILL IN PYRUVATEl. Glycolysis Overviewi. Used 2 ATPii. Made 4 ATPiii. Net gain = 2 ATPiv. Made 2 NADH- used in ETC to generate more ATPv. Oxygen present- citric acid cyclevi. No oxygen- fermentationvii. REDUCED State1. Glucose (REDUCING AGENT)2. NADHviii. OXIDIZED State1. Pyruvate2. NAD+ (OXIDIZING AGENT)ix. Oxidize glucose into pyruvate (remove electrons)x. Reduce NAD+ into NADH (add electrons)xi. OXYGEN NOT USED ANYWHERExii. PURPOSE: OXIDIZE GLUCOSEIII. Citric Acid Cycle (Kreb’s Cycle)a. Cycle completes oxidation of organic moleculesb. Before the citric acid cycle can begin, pyruvate must be converted to acetyl CoAc. OXIDIZES PYRUVATEd. Takes place within the mitochondrial matrixe. 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 turni. *Remember: 1 molecule of glucose = 2 turnsg. NADH & FADH2 shuttle high-energy electrons to electron transport chaini. FAD –flavin adenine dinucleotide, derived from B vitamin riboflavin, electron acceptorh. PYRUVATE DOES NOT GO INTO THIS CYCLE- ACETYL COA DOESi. 8 steps- each catalyzed by a different enzymei. Acetyl CoA combines with oxaloacetate to form citrateii. Step 2=unimportantiii. Isocitrate is oxidized. NAD+ is reduced to NADH. CO2 is removediv. CO2 is removed. NAD+ is reduced to NADHv. Phosphate is transferred to GDP forming GTP. GTP generates ATP (substrate level phosphorylation)vi. FADH2 is formedvii. Step 7=not importantviii. Malate is oxidized into oxaloacetate. NAD+ reduced to NADHj. Citric Acid Cycle Overviewi. I turn generates: 1 ATP, 3 NADH, 1 FADH21. 1 molecule glucose= 2 ATP, 6 NADH, 2 FADH2ii. NADH and FADH2 supply energy needed to make ATP by transferring electrons to electron transport chain.iii. Completing the oxidation of pyruvate.iv. REDUCED State1. NADH2. FADH23. Reducing agentsv. OXIDIZED State1. NAD+2. FAD3. Oxidizing agentsIV. Electron transport chaina. Occurs in the inner membrane of mitochondriab. Most components are multiprotein complexes (I- IV)c. Carriers alternate reduced & oxidized states as they accept & donate electronsd. Electrons drop in free energy as they go down the chain and are finally passed to O2, forming wateri. Moving HIGH energy ® LOW energye. Each component of the chain becomes reduced when it accepts electrons from its uphill neighborf. Becomes oxidized again as it passes the electron downhillg. SETS UP H+ GRADIENT h. Does not produce any ATP directlyi. Function is to break a large free energy drop into a series of small steps that release energy into manageable amounts; sets up H+ gradientj. Chemiosmosis couples this mechanism to ATP synthesisV. Cellular Respirationa. Importance of oxygenb. Without electronegative O2 to pull electrons down ETC, oxidative phosphorylation would stopVI. Chemiosmosisa. Use of energy in H+ gradient to drive cellular workb. Electron transfer in ETC causes proteins to pump H+ from the mitochondrial matrix into the intermembrane spacec. LOW H+ CONCENTRATION IN MATRIX= HIGHER pHd. HIGH H+ CONCENTRATION IN INTERMEMBRANE SPACE= LOWER pHe. H+ then moves back across the membrane (diffusion), passing through channelsin ATP synthase f. ATP synthase uses the exergonic flow of H+ to drive phosphorylation of ADPg. ATP synthase- located on inner membrane, enzyme actually makes ATP from ADP and Pih. ATP synthase uses energy from proton gradient to power ATP synthesisi. Power source for ATP synthase is the difference in the concentration of H + on opposite sides of the inner membrane (membrane potential)VII. ATP synthase is multisubunit complex:a. Rotor: within the membrane spins as shown when H+ flows past it down the H+ gradientb. Stator: anchored in the membrane holds the knob stationaryc. Rod: extending into the knob also spins, activating catalytic sites in the knobd. Knob: join inorganic phosphate to ADP to make