AP Bio Chapter 9: Cellular Respiration PDF

LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 9 Cellular Respiration and Fermentation...

LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 9 Cellular Respiration and Fermentation Lectures by Erin Barley Kathleen Fitzpatrick © 2011 Pearson Education, Inc. Overview: Life Is Work Living cells require energy from outside sources Some animals, such as the chimpanzee, obtain energy by eating plants, and some animals feed on other organisms that eat plants © 2011 Pearson Education, Inc.  Energy flows into an ecosystem as sunlight and leaves as heat Photosynthesis generates O2 and organic molecules, which are used in cellular respiration Cells use chemical energy stored in organic molecules to regenerate ATP, which powers work © 2011 Pearson Education, Inc. Figure 9.2 Light energy ECOSYSTEM Photosynthesis in chloroplasts Organic CO2  H2O molecules  O2 Cellular respiration in mitochondria ATP powers ATP most cellular work Heat energy  Catabolic Pathways and Production of ATP Fermentation is a partial degradation of sugars that occurs without O2 Aerobic respiration consumes organic molecules and O2 and yields ATP Anaerobic respiration is similar to aerobic respiration but consumes compounds other than O2 © 2011 Pearson Education, Inc.  Cellular respiration includes both aerobic and anaerobic respiration but is often used to refer to aerobic respiration Although carbohydrates, fats, and proteins are all consumed as fuel, it is helpful to trace cellular respiration with the sugar glucose C6H12O6 + 6 O2 6 CO2 + 6 H2O + Energy (ATP + heat) © 2011 Pearson Education, Inc.  The Principle of Redox Chemical reactions that transfer electrons between reactants are called oxidation-reduction reactions, or redox reactions In oxidation, a substance loses electrons, or is oxidized In reduction, a substance gains electrons, or is reduced (the amount of positive charge is reduced) © 2011 Pearson Education, Inc. OIL = Oxidation I LOOSE RedOx RIG = Reduction I GAIN  Oxidation of Organic Fuel Molecules During Cellular Respiration During cellular respiration, the ______________is oxidized, and___________ is reduced © 2011 Pearson Education, Inc.  Oxidation of Organic Fuel Molecules During Cellular Respiration During cellular respiration, the fuel (such as glucose) is oxidized, and O2 is reduced © 2011 Pearson Education, Inc.  Stepwise Energy Harvest via NAD+ and the Electron Transport Chain In cellular respiration, glucose and other organic molecules are broken down in a series of steps Electrons from organic compounds are usually first transferred to NAD+, a coenzyme As an electron acceptor, NAD+ functions as an oxidizing agent during cellular respiration Each NADH (the reduced form of NAD+) represents stored energy that is tapped to synthesize ATP © 2011 Pearson Education, Inc.  Stepwise Energy Harvest via NAD+ and the Electron Transport Chain NADH passes the electrons to the electron transport chain Unlike an uncontrolled reaction, the electron transport chain passes electrons in a series of steps instead of one explosive reaction O2 pulls electrons down the chain in an energy- yielding tumble The energy yielded is used to regenerate ATP © 2011 Pearson Education, Inc. Figure 9.5 H2  1/2 O2 2H  /2 O2 1 (from food via NADH) Controlled release of 2H  2e +  energy for synthesis of ATP ATP Elec chain Free energy, G Free energy, G tron Explosive ATP release of tran heat and light ATP energy port s 2 e 1 /2 O2 2H + H2O H2O (a) Uncontrolled reaction (b) Cellular respiration  The Stages of Cellular Respiration: A Preview Harvesting of energy from glucose has three stages – Glycolysis (breaks down glucose into two molecules of pyruvate) – The Citric Acid Cycle (completes the breakdown of glucose) – Oxidative phosphorylation (accounts for most of the ATP synthesis) © 2011 Pearson Education, Inc. Figure 9.6-1 Electrons carried via NADH Glycolysis Glucose Pyruvate CYTOSOL MITOCHONDRION ATP Substrate-level phosphorylation Figure 9.6-2 Electrons Electrons carried carried via NADH and via NADH FADH2 Pyruvate Glycolysis Citric oxidation acid Glucose Pyruvate Acetyl CoA cycle CYTOSOL MITOCHONDRION ATP ATP Substrate-level Substrate-level phosphorylation phosphorylation Figure 9.6-3 Electrons Electrons carried carried via NADH and via NADH FADH2 Oxidative Pyruvate Glycolysis Citric phosphorylation: oxidation acid electron transport Glucose Pyruvate Acetyl CoA cycle and chemiosmosis CYTOSOL MITOCHONDRION ATP ATP ATP Substrate-level Substrate-level Oxidative phosphorylation phosphorylation phosphorylation  Oxidative phosphorylation accounts for almost 90% of the ATP generated by cellular respiration A smaller amount of ATP is formed in glycolysis and the citric acid cycle by substrate-level phosphorylation For each molecule of glucose degraded to CO2 and water by respiration, the cell makes up to 32 molecules of ATP © 2011 Pearson Education, Inc. Figure 9.16 Electron shuttles MITOCHONDRION span membrane 2 NADH or 2 FADH2 2 NADH 2 NADH 6 NADH 2 FADH2 Glycolysis Pyruvate oxidation Oxidative Citric phosphorylation: Glucose 2 Pyruvate 2 Acetyl CoA acid electron transport cycle and chemiosmosis  2 ATP  2 ATP  about 26 or 28 ATP About Maximum per glucose: 30 or 32 ATP CYTOSOL  Concept 9.2: Glycolysis harvests chemical energy by oxidizing glucose to pyruvate Glycolysis (“splitting of sugar”) breaks down glucose into two molecules of pyruvate Glycolysis occurs whether or not O2 is present © 2011 Pearson Education, Inc. Figure 9.8 Energy Investment Phase Glucose 2 ADP  2 P 2 ATP used Energy Payoff Phase 4 ADP  4 P 4 ATP formed 2 NAD+  4 e  4 H+ 2 NADH  2 H+ 2 Pyruvate  2 H2O Net Glucose 2 Pyruvate  2 H2O 4 ATP formed  2 ATP used 2 ATP 2 NAD+  4 e  4 H+ 2 NADH  2 H+  Concept 9.3: After pyruvate is oxidized, the Citric Acid Cycle completes the energy-yielding oxidation of organic molecules In the presence of O2, pyruvate enters the mitochondrion (in eukaryotic cells) where the oxidation of glucose is completed © 2011 Pearson Education, Inc.  Oxidation of Pyruvate to Acetyl CoA (transition reaction linking glycolysis to citric acid cycle) Before the citric acid cycle can begin, pyruvate must be converted to acetyl Coenzyme A (acetyl CoA), which links glycolysis to the citric acid cycle This step is carried out by a multienzyme complex that catalyses three reactions © 2011 Pearson Education, Inc. Figure 9.10 MITOCHONDRION CYTOSOL CO2 Coenzyme A 1 3 2 NAD NADH + H Acetyl CoA Pyruvate Transport protein  The Citric Acid Cycle The citric acid cycle, also called the Krebs cycle, completes the break down of pyruvate to CO2 The cycle oxidizes organic fuel derived from pyruvate, generating (per turn, there are 2 turns): 1 ATP X2 = 2 ATP 3 NADH X2 = 6 NADH 1 FADH2 X2 = 2 FADH2 © 2011 Pearson Education, Inc. Figure 9.11 Pyruvate CO2 NAD  CoA NADH + H Acetyl CoA CoA CoA Citric acid cycle 2 CO2 FADH2 3 NAD FAD 3 NADH + 3 H ADP + P i ATP  The citric acid cycle has eight steps, each catalyzed by a specific enzyme The NADH and FADH2 produced by the cycle relay electrons extracted from food to the electron transport chain © 2011 Pearson Education, Inc. Figure 9.12-1 Acetyl CoA CoA-SH 1 Oxaloacetate Citrate Citric acid cycle Figure 9.12-2 Acetyl CoA CoA-SH 1 H2O Oxaloacetate 2 Citrate Isocitrate Citric acid cycle Figure 9.12-3 Acetyl CoA CoA-SH 1 H2O Oxaloacetate 2 Citrate Isocitrate NAD Citric 3 NADH acid + H cycle CO2 -Ketoglutarate Figure 9.12-4 Acetyl CoA CoA-SH 1 H2O Oxaloacetate 2 Citrate Isocitrate NAD Citric 3 NADH acid + H cycle CO2 CoA-SH -Ketoglutarate 4 CO2 NAD NADH Succinyl + H CoA Figure 9.12-5 Acetyl CoA CoA-SH 1 H2O Oxaloacetate 2 Citrate Isocitrate NAD Citric 3 NADH acid + H cycle CO2 CoA-SH -Ketoglutarate 4 CoA-SH 5 CO2 NAD Succinate Pi NADH GTP GDP Succinyl + H CoA ADP ATP Figure 9.12-6 Acetyl CoA CoA-SH 1 H2O Oxaloacetate 2 Citrate Isocitrate NAD Citric 3 NADH acid + H cycle CO2 Fumarate CoA-SH -Ketoglutarate 6 4 CoA-SH FADH2 5 CO2 NAD FAD Succinate Pi NADH GTP GDP Succinyl + H CoA ADP ATP Figure 9.12-7 Acetyl CoA CoA-SH 1 H2O Oxaloacetate 2 Malate Citrate Isocitrate NAD Citric 3 NADH 7 acid + H H2O cycle CO2 Fumarate CoA-SH -Ketoglutarate 6 4 CoA-SH FADH2 5 CO2 NAD FAD Succinate Pi NADH GTP GDP Succinyl + H CoA ADP ATP Figure 9.12-8 Acetyl CoA CoA-SH NADH + H 1 H2O NAD 8 Oxaloacetate 2 Malate Citrate Isocitrate NAD Citric 3 NADH 7 acid + H H2O cycle CO2 Fumarate CoA-SH -Ketoglutarate 6 4 CoA-SH FADH2 5 CO2 NAD FAD Succinate Pi NADH GTP GDP Succinyl + H CoA ADP ATP  Concept 9.4: During oxidative phosphorylation, chemiosmosis couples electron transport to ATP synthesis Following glycolysis and the citric acid cycle, NADH and FADH2 account for most of the energy extracted from food These two electron carriers donate electrons to the electron transport chain, which powers ATP synthesis via oxidative phosphorylation © 2011 Pearson Education, Inc.  The Pathway of Electron Transport The electron transport chain is in the inner membrane (cristae) of the mitochondrion © 2011 Pearson Education, Inc.  Most of the chain’s components are proteins, which exist in multi-protein complexes (Electron Transport Chain) Protons (H+) are pumped from the matrix to the intermembrane space by the ETC proteins Electrons go down the chain and are finally passed to O2 (final e- acceptor), forming H2O  Chemiosmosis: The Energy-Coupling Mechanism Electron transfer in the electron transport chain causes proteins to pump H+ from the mitochondrial matrix to the intermembrane space H+ then moves back across the membrane by diffusion (from high to low concentration), passing through ATP synthase ATP synthase uses the flow of H+ to drive phosphorylation of ATP This is an example of chemiosmosis, the use of energy in a H+ gradient to drive cellular work © 2011 Pearson Education, Inc. Figure 9.14 INTERMEMBRANE SPACE H Stator Rotor Internal rod Catalytic knob ADP + Pi ATP MITOCHONDRIAL MATRIX Figure 9.15 H H  Protein H  complex H Cyt c of electron carriers IV Q III I ATP II synth- 2 H + 1/2O2 H2O ase FADH2 FAD NADH NAD ADP  P i ATP (carrying electrons from food) H 1 Electron transport chain 2 Chemiosmosis Oxidative phosphorylation  An Accounting of ATP Production by Cellular Respiration During cellular respiration, most energy flows in this sequence: glucose NADH  electron transport chain chemiosmosis ATP About 34% of the energy in a glucose molecule is transferred to ATP during cellular respiration, making about 32 ATP There are several reasons why the number of ATP is not known exactly… © 2011 Pearson Education, Inc. Figure 9.16 Electron shuttles MITOCHONDRION span membrane 2 NADH or 2 FADH2 2 NADH 2 NADH 6 NADH 2 FADH2 Glycolysis Pyruvate oxidation Oxidative Citric phosphorylation: Glucose 2 Pyruvate 2 Acetyl CoA acid electron transport cycle and chemiosmosis  2 ATP  2 ATP  about 26 or 28 ATP About Maximum per glucose: 30 or 32 ATP CYTOSOL  Calculating ATP produced in https://www.khanacademy.org/test-prep/mcat/biomolecules/krebs-citric-acid-cycle-and-o cellular respiration xidative-phosphorylation/v/calculating-atp-produced-in-cellular-respiration  Direct products Ultimate ATP yield Stage (net) (net) Glycolysis 2 ATP 2 ATP 2 NADH 3-5 ATP Pyruvate oxidation 2 NADH 5 ATP Citric acid cycle 2 ATP/GTP 2 ATP 6 NADH 15 ATP 2 FADH_22​start subscript, 2, end 3 ATP subscript Total One number in this table is still not precise: the ATP30-32 ATP yield from NADH made in glycolysis. This is because glycolysis happens in the cytosol, and NADH can't cross the inner mitochondrial membrane to deliver its electrons to complex I. Instead, it must hand its electrons off to a molecular “shuttle system” that delivers them, through a series of steps, to the electron transport chain. Some cells of your body have a shuttle system that delivers electrons to the transport chain via FADH2. In this case, only 3 ATP are produced for the two NADH of glycolysis. Other cells of your body have a shuttle system that delivers the electrons via NADH, resulting in the production of 5 ATP. In bacteria, both glycolysis and the citric acid cycle happen in the cytosol, so no shuttle is needed and 5 ATP are produced. Cellular Respiration Overview | Glycolysis, Krebs Cycle & Electron Transport Chain - Bing video  Concept 9.5: Fermentation and anaerobic respiration enable cells to produce ATP without the use of oxygen Most cellular respiration requires O2 to produce ATP Without O2, the electron transport chain will cease to operate In that case, glycolysis couples with fermentation or ANaerobic respiration to produce ATP © 2011 Pearson Education, Inc.  Types of Fermentation Fermentation consists of glycolysis plus reactions that regenerate NAD+, which can be reused by glycolysis Two common types are lactic acid fermentation and alcohol fermentation. © 2011 Pearson Education, Inc.  Production of ATP in AErobic vs. ANaerobic Respiration  Lactic Acid fermentation In lactic acid fermentation, pyruvate is reduced to NADH, forming lactic acid as an end product, with no release of CO2 Lactic acid fermentation by some fungi and bacteria is used to make cheese and yogurt Human muscle cells use lactic acid fermentation to generate ATP when O2 is scarce © 2011 Pearson Education, Inc.  Alcoholic fermentation In alcohol fermentation, pyruvate is converted to ethanol in two steps, with the first releasing CO2 Alcohol fermentation by yeast is used in brewing, winemaking, and baking © 2011 Pearson Education, Inc. Comparing Fermentation with Anaerobic and Aerobic Respiration All use glycolysis (net ATP = 2) to oxidize glucose and harvest chemical energy of food In all three, NAD+ is the oxidizing agent that accepts electrons during glycolysis The processes have different final electron acceptors: an organic molecule (such as pyruvate or acetaldehyde) in fermentation and O2 in cellular respiration Cellular respiration produces 32 ATP per glucose molecule; fermentation produces 2 ATP per glucose molecule © 2011 Pearson Education, Inc.  Animation: Fermentation Overview Right-click slide / select “Play” © 2011 Pearson Education, Inc.  Obligate anaerobes carry out fermentation or anaerobic respiration and cannot survive in the presence of O2 Yeast and many bacteria are facultative anaerobes, meaning that they can survive using either fermentation or cellular respiration In a facultative anaerobe, pyruvate is a fork in the metabolic road that leads to two alternative catabolic routes © 2011 Pearson Education, Inc.  The Evolutionary Significance of Glycolysis Ancient prokaryotes are thought to have used glycolysis long before there was oxygen in the atmosphere Very little O2 was available in the atmosphere until about 2.7 billion years ago, so early prokaryotes likely used only glycolysis to generate ATP Glycolysis is a very ancient process!!! © 2011 Pearson Education, Inc.  Other Metabolic Pathways Involved in Glycolysis and the Citric Acid Cycle Regulation of Cellular Respiration through Feedback Mechanism FERMENTATION KIOSKS LACTIC ACID PRODUCTS ALCHOHOLIC PRODUCTS  Lactic Acid fermentation In lactic acid fermentation, pyruvate is reduced to NADH, forming lactic acid as an end product, with no release of CO2 Lactic acid fermentation by some fungi and bacteria is used to make cheese and yogurt Human muscle cells use lactic acid fermentation to generate ATP when O2 is scarce © 2011 Pearson Education, Inc.  Alcoholic fermentation In alcohol fermentation, pyruvate is converted to ethanol in two steps, with the first releasing CO2 Alcohol fermentation by yeast is used in brewing, winemaking, and baking © 2011 Pearson Education, Inc. The carbon dioxide produced in these reactions causes the dough to rise (ferment or prove), and the alcohol produced mostly evaporates from the dough during the baking process. During fermentation each yeast cell forms a centre around which carbon dioxide bubbles form. In making beer and wine, the carbon dioxide escapes from the fermenting liquid, and alcohol accumulates. In making bread both carbon dioxide and alcohol are trapped by the dough, and both are expelled from the dough by the heat of baking.