Score A class 2nd March 2012

Chapter 15: Cellular Respiration Chapter outlines: 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

1 Glycolysis

Stages in Glycolysis Glucose Glucose-6- phosphate Fructose-6- ATP ADP 1 Glucose-6- phosphate C C P 2 Fructose-6- phosphate C C P ATP ADP 3 Fructose-1,6- bisphosphate P C C P 4 Dihydroxyacetone- phosphate Glyceraldehyde-3- phosphate 5 C P C P

Stages in Glycolysis 1,3 bisphospho- glycerate 3 phospho- glycerate Glyceraldehyde-3- phosphate C P 6 NADH + H+ 1,3 bisphospho- glycerate C P 7 ATP 3 phospho- glycerate C P 8 2-phospho- glycerate C P 9 Phosphoenol- pyruvate C P 10 ATP Pyruvate C

Review of glycolysis 1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 Review of glycolysis Process Input Output 1. phosphorylation glucose ATP Glucose-6-phosphate ADP 2. isomerisation Fructose-6-phosphate 3. phosphorylation Fructose-1, 6-phosphate 4. Cleavage / lysis Dihydroxyacetone phosphate & Glyceraldehyde-3-phosphate 5. Isomerization Glyceraldehyde-3-phosphate 6. Oxidation and phosphorylation 2NAD+ 1, 3-bisphosphoglycerate 2NADH + H+ 7. Substrate-level phosphorylation 1,3-bisphospho-lycerate 2ADP 3-phosphoglycerate 2ATP 8. Isomerization 2-phosphoglycerate 9. Dehydration Phosphoenolpyruvate 10. Substrate-level phosphorylation phosphoenolpyruvate pyruvate 1 2 3 4 5 6 7 8 9 10 TOTAL: 2ATP, 2NAD+ 4ATP, 2NADH + H+

Chapter 15: Cellular Respiration 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]

2 Link Reaction Carbon dioxide CO2 Pyruvate NAD+ Coenzyme A NADH Acetyl coenzyme A Pyruvate Carbon dioxide CO2 NADH Link Reaction

Link Reaction Pyruvate Acetyl- CoA Decarboxylation 3C pyruvate NAD+ CoA NADH + H+ C Process Input Output Decarboxylation 3C pyruvate 2C compound Oxidation NAD+ 2C acetate (unstable) NADH + H+ (electron carrier) Attachment of Coenzyme Co-enzyme Acetyl-CoA reduction

3 Krebs cycle Krebs cycle 2 1 3 8 4 5 7 6 CoA C CoA C C C isocitrate Acetyl CoA releases CoA Krebs cycle CoA Citrate is converted to isocitrate C form acetyl group oxaloacetate isocitrate α-ketoglutarate Succinyl-CoA Succinate Fumarate Krebs cycle Malate Malate is oxidized by reducing NAD+ to NADH + H+ Regeneration of oxaloacetate 2 C C Acetyl group combine to oxaloacetate forming citrate Isocitrate undergoes oxidation and decarboxylation to form α-ketoglutarate Carbon dioxide formed. Hydrogen transferred from NAD+ to NADH + H+ 1 citrate 3 C NADH + H+ 8 C NADH + H+ 4 NADH + H+ α-ketoglutarate undergoes oxidation and decarboxylation and attached to an unstable bond to form succinyl-CoA. Carbon dioxide formed. Hydrogen transferred from NAD+ to NADH + H+ C C C Fumarate is converted to malate by addition of water. 5 7 ATP ADP GDP C FADH2 6 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 Succinate oxidized to form fumarate. Hydrogen transferred to FAD to form FADH2

Krebs cycle Krebs cycle 2 1 3 8 4 5 7 6 CoA C CoA C C C C isocitrate Acetyl CoA release CoA Krebs cycle CoA Citrate is converted to isocitrate C form acetyl group oxaloacetate isocitrate α-ketoglutarate Succinyl-CoA Succinate Fumarate Krebs cycle Malate 2 C C C 1 citrate 3 NAD+ NADH + H+ C 8 C NADH + H+ 4 C NAD+ NAD+ C NADH + H+ C C 5 7 ADP FAD GDP 6 FADH2 ATP GDP

Krebs cycle 2 1 3 8 4 7 5 6 CoA C CoA C C C isocitrate citrate C Acetyl CoA release CoA CoA form acetyl group oxaloacetate isocitrate α-ketoglutarate Succinyl-CoA Succinate Fumarate Malate C C 2 C NADH + H+ NAD+ citrate 1 3 C NADH + H+ NAD+ C 8 Krebs cycle 4 C NAD+ NADH + H+ FADH2 FAD 7 C C 5 ATP ADP GDP C ADP 6 ATP

Krebs cycle 2 3 1 8 4 7 5 6 CoA C C CoA C C C isocitrate C C citrate C Acetyl CoA release CoA CoA C form acetyl group 2 C C NADH + H+ NAD+ isocitrate C C 3 Acetyl group combine to oxaloacetate forming citrate citrate 1 C C C NADH + H+ oxaloacetate α-ketoglutarate 8 Krebs cycle NAD+ Malate C C 4 NAD+ NADH + H+ FAD 7 C C Fumarate FADH2 Succinyl-CoA C C ATP ADP GDP C C 5 ADP 6 Succinate ATP

Acetyl coenzyme A Coenzyme A Citrate Oxaloacetate NADH NAD+ NAD+ C I T R I C A C I D C Y C L E H2O NADH CO2 FADH2 5-carbon compound FAD Figure 8.6: Overview of the citric acid cycle. For every glucose, two acetyl groups enter the citric acid cycle (top). Each two-carbon acetyl group combines with a four-carbon compound, oxaloacetate, to form the six-carbon compound citrate. Two CO2 molecules are removed, and energy is captured as one ATP, three NADH, and one FADH2 per acetyl group (or two ATPs, six NADH, and two FADH2 per glucose molecule). NADH GTP GDP CO2 4-carbon compound ADP ATP

Chapter 15: Cellular Respiration PSPM 2009/10 6. (a) Explain the steps in Krebs cycle that produce high energy molecules. [10 marks] 1 2 8 KREBS CYCLE 3 4 7 6 5

Chapter 15: Cellular Respiration PSPM 2007/08 Chapter 15: Cellular Respiration 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 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] FIGURE 3

Electron carriers: NADH & FADH2

Electron Transport Chain 4 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 captures energy generates uses process of redox reactions Chemisosmosis as ATP which uses electrons to form proton gradient creates in synthesis of from phosphorylation which is NADH inter membrane space to undergo proton motive force is pumped into passed down ADP Electron Transport Chain whereby H⁺ drives H⁺ through catalyzes finally to ATP synthase final electron acceptor which is oxygen producing water

Chapter 15: Cellular Respiration 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]

Chapter 15: Cellular Respiration PSPM 2006/07 Chapter 15: Cellular Respiration 6. (b) Compare and contrast between fermentation and aerobic respiration. [8 marks]

Chapter 15: Cellular Respiration 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]

Reaction ATP 2 ATP 6 ATP 18 ATP 4 ATP 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 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) 6 ATP 18 ATP 4 ATP Total = 36 ATP

38 ATP from active cell Reaction ATP 1. Glycolysis 2 ATP 2. Krebs cycle 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) 6 ATP 18 ATP 4 ATP Total = 38 ATP

Energy Harvested from Glucose (Cytoplasm) Glucose Glycolysis 4 ATP 2 ATP 2 Pyruvates (Mitochondrial Matrix) 2 NADH 2 CO2 2 NADH Krebs Cycle 6 NADH 4 CO2 2 FADH2 2 ATP (Inner Membrane) Water Electron Transport System 32 ATP Oxygen

Anaerobic Respiration

Chapter 15: Cellular Respiration PSPM 2004/05 Chapter 15: Cellular Respiration 6. (a) Compare between aerobic and anaerobic respirations. [8 marks]

Chapter 15: Cellular Respiration PSPM 2005/06 Chapter 15: Cellular Respiration 6. (b) Explain the production of lactic acid during anaerobic respiration. [6 marks]

Chapter 15: Cellular Respiration PSPM 2009/10 6. (b) Discuss the fermentation pathways under anaerobic condition that occurs in plant and animal cells. [10 marks]

Chapter 15: Cellular Respiration PSPM 2010/11 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. (ii) Give ONE example of the importance of this process in industry. ___________________________________ ___________________________________ [1m] (c) Name the process N. ______________________________________________ [1m] (d) Name the substances J,K, L and M. Substance J : ___________________________________________________ Substance K : ___________________________________________________ Substance L : ___________________________________________________ Substance M : ___________________________________________________ [4m] (e) How many ATP molecules are produced from the process in FIGURE 3? ________________________________________________________________ [1m] (f) What is the role of NADH2 in the above process? _________________________________________________________________ [1m]

Figure 8.4: A detailed look at glycolysis. A specific enzyme catalyzes each of the reactions in glycolysis. Note the net yield of two ATP molecules and two NADH molecules. (The black wavy lines indicate bonds that permit the phosphates to be readily transferred to other molecules; in this case, ADP.)

The Krebs cycle

Acetyl coenzyme A Coenzyme A Citrate Oxaloacetate NADH NAD+ NAD+ C I T R I C A C I D C Y C L E H2O NADH CO2 FADH2 5-carbon compound FAD Figure 8.6: Overview of the citric acid cycle. For every glucose, two acetyl groups enter the citric acid cycle (top). Each two-carbon acetyl group combines with a four-carbon compound, oxaloacetate, to form the six-carbon compound citrate. Two CO2 molecules are removed, and energy is captured as one ATP, three NADH, and one FADH2 per acetyl group (or two ATPs, six NADH, and two FADH2 per glucose molecule). NADH GTP GDP CO2 4-carbon compound ADP ATP

Chapter 15: Cellular Respiration PSPM 2003/04 Chapter 15: Cellular Respiration 6. With reference to a labelled diagram, describe Krebs cycle. [20 marks]

Complex I: NADH–ubiquinone oxidoreductase Cytosol Outer mitochondrial membrane Intermembrane space Complex I: NADH–ubiquinone oxidoreductase Complex IV: Cytochrome c oxidase Complex III: Ubiquinone– cytochrome c oxidoreductase Inner mitochondrial membrane Complex II: Succinate– ubiquinone reductase Figure 8.8: An overview of the electron transport chain. Electrons fall to successively lower energy levels as they are passed along the four complexes of the electron transport chain located in the inner mitochondrial membrane. (The orange arrows indicate the pathway of electrons.) The carriers within each complex become alternately reduced and oxidized as they accept and donate electrons. The terminal acceptor is oxygen; one of the two atoms of an oxygen molecule (written as 1/2 O2) accepts 2 electrons, which are added to 2 protons from the surrounding medium to produce water. Matrix of mitochondrion FADH2 FAD 2 H+ H2O NAD+ 1/2 O2 NADH

Cytosol Outer mitochondrial membrane Intermembrane space Complex V: ATP synthase Complex III Complex IV Inner mitochondrial membrane Complex I Complex II Matrix of mitochondrion FADH2 Figure 8.10: A detailed look at electron transport and chemiosmosis. NAD+ 1 2 NADH ADP Pi ATP

Outer mitochondrial membrane Cytosol Inner mitochondrial membrane Figure 8.9: The accumulation of protons (H+) within the intermembrane space. As electrons move down the electron transport chain, the electron transport complexes move protons (H+) from the matrix to the intermembrane space, creating a proton gradient. The high concentration of H+ in the intermembrane space lowers the pH. Intermembrane space — low pH Matrix — higher pH

Let’s count 2 1

3 4

Aerobic Respiration: Energy yield 2 ATP Pyruvate Glucose Glycolysis 4/6 ATP 2 NADH 6 ATP 2 NADH Acetyl-CoA 2 ATP Krebs cycle 18 ATP 6 NADH 4 ATP 2 FADH2 Total net ATP yield = 36/38 ATP Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Tally the ATP

Substrate-level phosphorylation Oxidative phosphorylation Glycolysis Glucose Pyruvate Acetyl coenzyme A Citric acid cycle Figure 8.11: Energy yield from the complete oxidation of glucose by aerobic respiration. Total ATP from substrate-level phosphorylation Total ATP from oxidative phosphorylation

Complete the table below Glycolysis Formation of Acetyl CoA and Citric Acid Cycle Electron Transport and Chemiosmosis Where does this occur in the cell? What are the input molecules? What is the carbon-based output molecule? ATP production? Electron carriers?

Chapter 15: Cellular Respiration PSPM 2008/09 Chapter 15: Cellular Respiration 7. (a) Explain how protein and lipid are used as alternative energy source. [8 marks]