PowerLecture: Chapter 8 How Cells Release Stored Energy.

  • Published on
    25-Dec-2015

  • View
    213

  • Download
    1

Transcript

<ul><li> Slide 1 </li> <li> PowerLecture: Chapter 8 How Cells Release Stored Energy </li> <li> Slide 2 </li> <li> More than 100 mitochondrial disorders are known Friedreichs ataxia, caused by a mutant gene, results in loss of cordination, weak muscles, and visual problems Animal, plants, fungus, and most protists depend on structurally sound mitochondria Defective mitochondria can result in life threatening disorders Impacts, Issues: When Mitochondria Spin Their Wheels </li> <li> Slide 3 </li> <li> Fig. 8-1, p.122 When Mitochondria Spin Their Wheels </li> <li> Slide 4 </li> <li> Descendents of African honeybees that were imported to Brazil in the 1950s More aggressive, wider-ranging than other honeybees Africanized bees muscle cells have large mitochondria Killer Bees </li> <li> Slide 5 </li> <li> Photosynthesizers get energy from the sun Animals get energy second- or third-hand from plants or other organisms Regardless, the energy is converted to the chemical bond energy of ATP ATP Is Universal Energy Source </li> <li> Slide 6 </li> <li> Making ATP Making ATP Plants make ATP during photosynthesis Cells of all organisms make ATP by breaking down carbohydrates, fats, and protein </li> <li> Slide 7 </li> <li> Main Types of Energy-Releasing Pathways Aerobic pathways Evolved later Require oxygen Start with glycolysis in cytoplasm Completed in mitochondria Anaerobic pathways Evolved first Dont require oxygen Start with glycolysis in cytoplasm Completed in cytoplasm </li> <li> Slide 8 </li> <li> start (glycolysis) in cytoplasm completed in mitochondrion start (glycolysis) in cytoplasm completed in cytoplasm Aerobic Respiration Anaerobic Energy- Releasing Pathways Fig. 8-2, p.124 Main Types of Energy-Releasing Pathways </li> <li> Slide 9 </li> <li> Summary Equation for Aerobic Respiration C 6 H 12 0 6 + 6O 2 6CO 2 + 6H 2 0 glucose oxygen carbon water glucose oxygen carbon water dioxide dioxide </li> <li> Slide 10 </li> <li> Overview of Aerobic Respiration CYTOPLASM Glycolysis Electron Transfer Phosphorylation Krebs Cycle ATP 2 CO 2 4 CO 2 2 32 water 2 NADH 8 NADH 2 FADH 2 2 NADH 2 pyruvate e - + H + e - + oxygen (2 ATP net) glucose Typical Energy Yield: 36 ATP e-e- e - + H + ATP H+H+ e - + H + ATP 2 4 Fig. 8-3, p. 135 </li> <li> Slide 11 </li> <li> The Role of Coenzymes NAD + and FAD accept electrons and hydrogen Become NADH and FADH 2 Deliver electrons and hydrogen to the electron transfer chain </li> <li> Slide 12 </li> <li> A simple sugar (C 6 H 12 O 6 ) Atoms held together by covalent bonds Glucose In-text figure Page 126 </li> <li> Slide 13 </li> <li> Glycolysis Occurs in Two Stages Glycolysis Occurs in Two Stages Energy-requiring steps ATP energy activates glucose and its six-carbon derivatives ATP energy activates glucose and its six-carbon derivatives Energy-releasing steps The products of the first part are split into three- carbon pyruvate molecules The products of the first part are split into three- carbon pyruvate molecules ATP and NADH form ATP and NADH form </li> <li> Slide 14 </li> <li> GLUCOSE glucose GYCOLYSIS pyruvate to second stage of aerobic respiration or to a different energy-releasing pathway Fig. 8-4a, p.126 Glycolysis </li> <li> Slide 15 </li> <li> ATP 2 ATP invested ENERGY-REQUIRING STEPS OF GLYCOLYSIS glucose ADP P P P P glucose6phosphate fructose6phosphate fructose1,6bisphosphate DHAP Fig. 8-4b, p.127 Glycolysis </li> <li> Slide 16 </li> <li> ATP ADP ENERGY-RELEASING STEPS OF GLYCOLYSIS NAD + P PGAL 1,3bisphosphoglycerate substrate-level phsphorylation PiPi 1,3bisphosphoglycerate ATP NADH P PGAL NAD + PiPi PPPP 3phosphoglycerate PP 2 ATP invested ADP Fig. 8-4c, p.127Glycolysis </li> <li> Slide 17 </li> <li> 2 ATP produced ATP ADP P substrate-level phsphorylation 2phosphoglycerate ATP P pyruvate ADP PP 2phosphoglycerate H2OH2OH2OH2O PEP Fig. 8-4d, p.127 Glycolysis </li> <li> Slide 18 </li> <li> Slide 19 </li> <li> Slide 20 </li> <li> Glycolysis: Net Energy Yield Glycolysis: Net Energy Yield Energy requiring steps: Energy requiring steps: 2 ATP invested 2 ATP invested Energy releasing steps: 2 NADH formed 4 ATP formed Net yield is 2 ATP and 2 NADH </li> <li> Slide 21 </li> <li> Second Stage Reactions Second Stage Reactions Preparatory reactions Pyruvate is oxidized into two-carbon acetyl units and carbon dioxide Pyruvate is oxidized into two-carbon acetyl units and carbon dioxide NAD + is reduced NAD + is reduced Krebs cycle The acetyl units are oxidized to carbon dioxide The acetyl units are oxidized to carbon dioxide NAD + and FAD are reduced NAD + and FAD are reduced </li> <li> Slide 22 </li> <li> inner mitochondrial membrane outer mitochondrial membrane inner compartment outer compartment Fig. 8-6a, p.128 Second Stage Reactions Second Stage Reactions </li> <li> Slide 23 </li> <li> Preparatory Reactions pyruvate NAD + NADH coenzyme A (CoA) OO carbon dioxide CoA acetyl-CoA </li> <li> Slide 24 </li> <li> The Krebs Cycle Overall Products Coenzyme A 2 CO 2 3 NADH FADH 2 ATP Overall Reactants Acetyl-CoA 3 NAD + FAD ADP and P i </li> <li> Slide 25 </li> <li> Acetyl-CoA Formation acetyl-CoA (CO 2 ) pyruvate coenzyme A NAD + NADH CoA Krebs Cycle CoA NADH FADH 2 NADH ATP ADP + phosphate group NAD + FAD oxaloacetate citrate Fig. 8-7a, p.129 Preparatory Reactions </li> <li> Slide 26 </li> <li> Slide 27 </li> <li> Results of the Second Stage All of the carbon molecules in pyruvate end up in carbon dioxide Coenzymes are reduced (they pick up electrons and hydrogen) One molecule of ATP forms Four-carbon oxaloacetate regenerates </li> <li> Slide 28 </li> <li> Two pyruvates cross the inner mitochondrial membrane. outer mitochondrial compartment NADH FADH 2 ATP 2 6 2 2 Krebs Cycle 6 CO 2 inner mitochondrial compartment Eight NADH, two FADH 2, and two ATP are the payoff from the complete break- down of two pyruvates in the second-stage reactions. The six carbon atoms from two pyruvates diffuse out of the mitochondrion, then out of the cell, in six CO Fig. 8-6b, p.128 </li> <li> Slide 29 </li> <li> Coenzyme Reductions during First Two Stages Glycolysis2 NADH Preparatory reactions 2 NADH Krebs cycle 2 FADH 2 + 6 NADH Total 2 FADH 2 + 10 NADH </li> <li> Slide 30 </li> <li> glucose glycolysis ee KREBS CYCLE electron transfer phosphorylation 2 PGAL 2 pyruvate 2 NADH 2 CO 2 ATP 2 FADH 2 H+H+ 2 NADH 6 NADH 2 FADH 2 2 acetyl-CoA ATP 2 Krebs Cycle 4 CO 2 ATP 36 ADP + P i H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ Fig. 8-9, p.131Phosphorylation </li> <li> Slide 31 </li> <li> Occurs in the mitochondria Coenzymes deliver electrons to electron transfer chains Electron Transfer Phosphorylation </li> <li> Slide 32 </li> <li> Creating an H + Gradient NADH OUTER COMPARTMENT INNER COMPARTMENT Electron transfer sets up H + ion gradients </li> <li> Slide 33 </li> <li> Making ATP: Chemiosmotic Model ATP ADP + P i INNER COMPARTMENT Flow of H + down gradients powers ATP formation </li> <li> Slide 34 </li> <li> Importance of Oxygen Electron transport phosphorylation requires the presence of oxygen Oxygen withdraws spent electrons from the electron transfer chain, then combines with H + to form water </li> <li> Slide 35 </li> <li> Do not use oxygen Produce less ATP than aerobic pathways Two types Fermentation pathways Fermentation pathways Anaerobic electron transport Anaerobic electron transport Anaerobic Pathways </li> <li> Slide 36 </li> <li> Fermentation Pathways Fermentation Pathways Begin with glycolysis Do not break glucose down completely to carbon dioxide and water Yield only the 2 ATP from glycolysis Steps that follow glycolysis serve only to regenerate NAD + </li> <li> Slide 37 </li> <li> C 6 H 12 O 6 ATP NADH 2 acetaldehyde electrons, hydrogen from NADH 2 NAD + 2 2 ADP 2 pyruvate 2 4 energy output energy input glycolysis ethanol formation 2 ATP net 2 ethanol 2 H 2 O 2 CO 2 Fig. 8-10d, p.132 Alcoholic Fermentation </li> <li> Slide 38 </li> <li> C 6 H 12 O 6 ATP NADH 2 lactate electrons, hydrogen from NADH 2 NAD + 2 2 ADP 2 pyruvate 2 4 energy output energy input glycolysis lactate fermentation 2 ATP net Fig. 8-11, p.133 Lactate Fermentation </li> <li> Slide 39 </li> <li> Anaerobic Electron Transport Carried out by certain bacteria Electron transfer chain is in bacterial plasma membrane Final electron acceptor is compound from environment (such as nitrate), not oxygen ATP yield is low </li> <li> Slide 40 </li> <li> Summary of Energy Harvest (per molecule of glucose) Glycolysis 2 ATP formed by substrate-level phosphorylation 2 ATP formed by substrate-level phosphorylation Krebs cycle and preparatory reactions 2 ATP formed by substrate-level phosphorylation 2 ATP formed by substrate-level phosphorylation Electron transport phosphorylation 32 ATP formed 32 ATP formed </li> <li> Slide 41 </li> <li> Energy Harvest Varies NADH formed in cytoplasm cannot enter mitochondrion It delivers electrons to mitochondrial membrane Membrane proteins shuttle electrons to NAD + or FAD inside mitochondrion Electrons given to FAD yield less ATP than those given to NAD + </li> <li> Slide 42 </li> <li> 686 kcal of energy are released 7.5 kcal are conserved in each ATP When 36 ATP form, 270 kcal (36 X 7.5) are captured in ATP Efficiency is 270 / 686 X 100 = 39 percent Most energy is lost as heat Efficiency of Aerobic Respiration </li> <li> Slide 43 </li> <li> FOOD fatsglycogen complex carbohydrates proteins simple sugars (e.g., glucose) amino acids glucose-6- phosphate carbon backbones NH 3 urea ATP (2 ATP net) PGAL glycolysis ATP 2 glycerol fatty acids NADHpyruvate acetyl-CoA NADH CO 2 Krebs Cycle NADH, FADH 2 CO 2 ATP many ATP water H+H+ e + oxygen ee 4 ATP 2 Fig. 8-13b, p.135 electron transfer phosphorylation Alternative Energy Sources </li> <li> Slide 44 </li> <li> When life originated, atmosphere had little oxygen Earliest organisms used anaerobic pathways Later, noncyclic pathway of photosynthesis increased atmospheric oxygen Cells arose that used oxygen as final acceptor in electron transport Evolution of Metabolic Pathways </li> <li> Slide 45 </li> <li> p.136b Processes Are Linked </li> </ul>

Recommended

View more >