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Chapter 15: Cellular Respiration Chapter outlines: i. ii. iii. iv. v. vi. vii. Structure of ATP & its role in living organisms Process of ATP production: substrate level & oxidative phosphorylation Describe glycolysis, link reaction & Krebs cycle Describe ETC and chemiosmosis Explain how active cells derive 38 ATPs Explain complete oxidation of 1 molecule of glucose Describe alcoholic and lactate fermentation Overview of Cellular Respiration Redox & the role of NAD as electron carrier Substrate Level Phosphorylation & Oxidative Phosphorylation Glycolysis Stages in Glycolysis Glucose ATP ADP Glucose-6phosphate Fructose-6phosphate ATP ADP Fructose-1,6bisphosphate Dihydroxyacetonephosphate Glyceraldehyde-3phosphate Stages in Glycolysis Glyceraldehyde-3phosphate NADH + H+ 1,3 bisphosphoglycerate ATP 3 phosphoglycerate 2-phosphoglycerate Phosphoenolpyruvate ATP Pyruvate Review of glycolysis 1 2 3 4 5 6 7 8 9 10 Review of glycolysis Process 1 Input Output 1. phosphorylation glucose ATP Glucose-6-phosphate ADP 2. isomerisation Glucose-6-phosphate Fructose-6-phosphate 3. phosphorylation Fructose-6-phosphate ATP Fructose-1, 6-phosphate ADP 4 4. Cleavage / lysis Fructose-1, 6-phosphate Dihydroxyacetone phosphate & Glyceraldehyde-3-phosphate 5 5. Isomerization Dihydroxyacetone phosphate & Glyceraldehyde-3-phosphate Glyceraldehyde-3-phosphate 6. Oxidation and phosphorylation Glyceraldehyde-3-phosphate 2NAD+ 1, 3-bisphosphoglycerate 2NADH + H+ 7. Substrate-level phosphorylation 1,3-bisphospho-lycerate 2ADP 3-phosphoglycerate 2ATP 8. Isomerization 3-phosphoglycerate 2-phosphoglycerate 9. Dehydration 2-phosphoglycerate Phosphoenolpyruvate 10. Substrate-level phosphorylation phosphoenolpyruvate 2ADP pyruvate 2ATP 2 3 6 7 8 9 10 TOTAL: 2ATP, 2NAD+ 4ATP, 2NADH + H+ PSPM 2008/09 Chapter 15: Cellular Respiration 2. FIGURE 2 shows some of the steps involved in cellular respiration in muscle tissues. (a) Name the process which involves the above steps. _________________________________ [1m] (b) In which TWO steps are ATPS being used? Why is ATP used? __________________________________________ __________________________________________ __________________________________________ [3m] (c) Name the enzymes involved in steps P and Q. Step P : _________________________ Step Q : _________________________ [2m] (d) In which step is NADH produced? State the function of NADH. __________________________________________ __________________________________________ [2m] (e) How many molecules of NADH and pyruvate are produced from one molecule of 1.3-bisphosphoglyerate? ___________________________________________ [2m] Link Reaction Carbon dioxide CO2 Pyruvate NAD+ Coenzyme A NADH Acetyl coenzyme A Link Reaction CO2 Pyruvate Acetyl- CoA NAD+ Process NADH + H+ Input Output Decarboxylation 3C pyruvate 2C compound Oxidation 2C compound reduction NAD+ 2C acetate (unstable) NADH + H+ (electron carrier) Attachment of Coenzyme Co-enzyme Acetyl-CoA Acetyl CoA releases CoA Krebs cycle Citrate is converted to isocitrate form acetyl group 2 Acetyl group combine to oxaloacetate forming citrate 1 isocitrate citrate 3 NADH + H+ oxaloacetate Malate is oxidized by reducing NAD+ to NADH + H+ 8 Regeneration of oxaloacetate Isocitrate undergoes oxidation and decarboxylation to form α-ketoglutarate Carbon dioxide formed. Hydrogen transferred from NAD+ to NADH + H+ α-ketoglutarate Krebs cycle NADH + H+ 4 NADH + H+ Malate Fumarate Fumarate is converted to malate by addition of water. Succinyl-CoA Succinate 7 5 GDP GDP FADH2 Succinate oxidized to form fumarate. Hydrogen transferred to FAD to form FADH2 6 α-ketoglutarate undergoes oxidation and decarboxylation and attached to an unstable bond to form succinylCoA. Carbon dioxide formed. Hydrogen transferred from NAD+ to NADH + H+ ADP ATP CoA is displaced by a phosphate group, GDP phosphorylated to GTP and then ADP form ATP by substrate-level phosphorylation Succinyl-CoA converted to succinate Acetyl CoA release CoA Krebs cycle Citrate is converted to isocitrate form acetyl group 2 1 isocitrate citrate 3 NAD+ NADH + H+ oxaloacetate α-ketoglutarate 8 Krebs cycle NADH + H+ NAD+ 4 Malate Succinyl-CoA NAD+ Fumarate Succinate NADH + H+ 5 7 GDP FAD ADP 6 FADH2 ATP GDP Acetyl CoA release CoA form acetyl group 2 1 isocitrate NAD+ citrate 3 NADH + H+ oxaloacetate NADH + H+ 8 Krebs cycle NAD+ α-ketoglutarate Malate 4 FAD 7 Fumarate Succinyl-CoA FADH2 5 6 Succinate Acetyl CoA release CoA form acetyl group 2 NAD+ isocitrate Acetyl group combine to oxaloacetate forming citrate 1 3 citrate oxaloacetate NADH + H+ 8 α-ketoglutarate Krebs cycle NAD+ Malate 4 FAD 7 NADH + H+ Fumarate Succinyl-CoA FADH2 6 5 Succinate Acetyl coenzyme A Coenzyme A Citrate Oxaloacetate NADH NAD+ NAD+ CITRIC ACID CYCLE H2O NADH CO2 FADH2 5-carbon compound FAD NADH GTP GDP 4-carbon compound ADP ATP CO2 Chapter 15: Cellular Respiration PSPM 2009/10 6. (a) Explain the steps in Krebs cycle that produce high energy molecules. 1 2 8 KREBS CYCLE 3 4 7 6 5 [10 marks] Chapter 15: Cellular Respiration PSPM 2007/08 3. FIGURE 3 represents two main stages in cellular respiration. (a) Name the reaction that occurs at steps 2, 3 and 4 and the TWO by-products of the reaction. (i) Reaction : ______ [1m] (ii) By-products: ______ [2m] (b) At which step does the substrate level phosphorylation occur, and how ATP(s) are produced at this step from one molecule of glucose? (i) Step : _____ (ii) ATP(s) _______ [2m] (c) State what happens to the hydrogen produced at step 6 [2m] ________________________________________________ ________________________________________________ (d) Identify compound X. _________________ [1m] (e) The reduced co-enzyme produced in step 1 will enter the FIGURE 3 electron transport system. (i) What is the reduced co-enzyme? _______ [1m] (ii) What is the reaction involved in the production of ATP when the reduced co-enzyme in e(i) enters the electron transport system? _________________ [1m] Electron carriers: NADH & FADH2 Electron Transport Chain Oxidative phosphorylation: Electron Transport Chain & Chemiosmosis • ETC consists of 3 protein complexes: NADH dehydrogenase complex, cytochrome complex and two mobile carriers • The hydrogen atom from the NADH is transferred to NADH dehydrogenase whereby it will split into proton (H+) and electrons. • Electrons will reduce NADH dehydrogenase / reductase while NADH is oxidized to NAD+ as electron pass along the electron transport chain. • As electron is transferred to ubiquinone (Coenzyme Q), NADH dehydrogenase is oxidized while ubiquinone will be reduced. • Electrons will be passed to cyctochrome b, cytochrome b, and then cytochrome a. • The last electron acceptor is oxygen molecule. Oxygen will be reduced to form water. Oxidative phosphorylation: Electron Transport Chain & Chemiosmosis • Energy is released as electrons are passed along the electron transport chain. The energy is used to pump hydrogen ions (H+) from the matrix to the intermembrane space. • This builds up a gradient across the inner membrane of the mitochondrion. • Which forces H+ to diffuse through the ATP synthase down its concentration gradient. • The energy released is used to synthesise ATP from ADP and Pi • This process is known as chemiosmosis. Oxidative phosphorylation: Electron Transport Chain & Chemiosmosis Oxidative Phosphorylation uses process of redox reactions Chemisosmosis as which uses electrons proton gradient from inter membrane space NADH passed down Electron Transport Chain is pumped into whereby proton motive force to form phosphorylation to undergo ADP H⁺ catalyzes finally to final electron acceptor ATP synthase which is oxygen which is ATP producing water PSPM 2006/07 Chapter 15: Cellular Respiration 6. (a) Explain how electrons from NADH and FADH2 flow through the electron transport chain with the production of ATP. [12 marks] PSPM 2006/07 Chapter 15: Cellular Respiration 6. (b) Compare and contrast between fermentation and aerobic respiration. [8 marks] PSPM 2004/05 Chapter 15: Cellular Respiration 6. (b) Describe the stages in the production of NADH and its role in cellular respiration. [12 marks] PSPM 2005/06 Chapter 15: Cellular Respiration 6. (a) Describe how one molecule of glucose is able to produce 36 ATP via aerobic respiration. [14 marks] Reaction ATP 1. Glycolysis 2 ATP 2. Krebs cycle 2 ATP 3. ETC • 2 NADH from link reaction • 6 NADH from 2 Krebs cycle • 2 FADH2 from 2 Krebs cycle • Glycerol phosphate shuttle: (2 NADH from glycolysis produce 2 FADH2) Total 6 ATP 18 ATP 4 ATP 4 ATP = 36 ATP 38 ATP from active cell Reaction ATP 1. Glycolysis 2 ATP 2. Krebs cycle 2 ATP 3. ETC • 2 NADH from link reaction • 6 NADH from 2 Krebs cycle • 2 FADH2 from 2 Krebs cycle • Malate shuttle: (2 NADH from glycolysis produce 2 NADH) Total 6 ATP 18 ATP 4 ATP 6 ATP = 38 ATP Energy Harvested from Glucose Glucose (Cytoplasm) 2 ATP (Mitochondrial Matrix) (Inner Membrane) Oxygen 4 ATP Glycolysis 2 NADH 2 NADH 6 NADH 2 FADH2 2 Pyruvates Krebs Cycle Electron Transport System 2 CO2 4 CO2 2 ATP Water 32 ATP Anaerobic Respiration PSPM 2004/05 Chapter 15: Cellular Respiration 6. (a) Compare between aerobic and anaerobic respirations. [8 marks] PSPM 2005/06 6. Chapter 15: Cellular Respiration (b) Explain the production of lactic acid during anaerobic respiration. [6 marks] PSPM 2009/10 Chapter 15: Cellular Respiration 6. (b) Discuss the fermentation pathways under anaerobic condition that occurs in plant and animal cells. [10 marks] PSPM 2010/11 Chapter 15: Cellular Respiration 3. FIGURE 3 shows a schematic diagram of cellular respiration. (a) Name the type of cellular respiration show in FIGURE 3. _________________________ [1m] (b) (i) State in what condition does the cellular respiration in 3(a) to occur. _________________________ [1m] (ii) Give ONE example of the importance of this process in industry. ___________________________________ ___________________________________ [1m] (c) Name the process N. ______________________________________________ (d) Name the substances J,K, L and M. Substance J : ___________________________________________________ Substance K : ___________________________________________________ Substance L : ___________________________________________________ Substance M : ___________________________________________________ (e) How many ATP molecules are produced from the process in FIGURE 3? ________________________________________________________________ (f) What is the role of NADH2 in the above process? _________________________________________________________________ [1m] [4m] [1m] [1m] The Krebs cycle Acetyl coenzyme A Coenzyme A Citrate Oxaloacetate NADH NAD+ NAD+ CITRIC ACID CYCLE H2O NADH CO2 FADH2 5-carbon compound FAD NADH GTP GDP 4-carbon compound ADP ATP CO2 PSPM 2003/04 Chapter 15: Cellular Respiration 6. With reference to a labelled diagram, describe Krebs cycle. [20 marks] Cytosol Outer mitochondrial membrane Intermembrane space Complex I: NADH– ubiquinone Inner oxidoreductase mitochondrial membrane Matrix of mitochondrion Complex II: Succinate– ubiquinone reductase Complex IV: Cytochrome c oxidase Complex III: Ubiquinone– cytochrome c oxidoreductase FADH2 FAD NAD+ NADH 2 H+ H2O 1/ 2 O2 Cytosol Outer mitochondrial membrane Intermembrane space Inner mitochondrial membrane Complex I Matrix of mitochondrion Complex II Complex III Complex V: ATP synthase Complex IV FADH2 NAD+ NADH 1 2 ADP Pi ATP Outer mitochondrial membrane Cytosol Inner mitochondrial membrane Intermembrane space — low pH Matrix — higher pH Let’s count Aerobic Respiration: Energy yield Glucose 2 ATP 2 ATP 2 NADH 4/6 ATP 2 NADH 6 ATP 2 ATP 6 NADH 18 ATP 2 FADH2 4 ATP Total net ATP yield = 36/38 ATP Glycolysis Pyruvate Acetyl-CoA Krebs cycle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Tally the ATP Substrate-level phosphorylation Glycolysis Oxidative phosphorylation Glucose Pyruvate Acetyl coenzyme A Citric acid cycle Total ATP from substrate-level phosphorylation Total ATP from oxidative phosphorylation Complete the table below Glycolysis Where does this occur in the cell? What are the input molecules? What is the carbonbased output molecule? ATP production? Electron carriers? Formation of Acetyl CoA and Citric Acid Cycle Electron Transport and Chemiosmosis PSPM 2008/09 Chapter 15: Cellular Respiration 7. (a) Explain how protein and lipid are used as alternative energy source. [8 marks]