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Chapter 9 How Cells Harvest Chemical Energy

Chapter 9 How Cells Harvest Chemical Energy. Introduction to Cell Metabolism Glycolysis Aerobic Cell Respiration Anaerobic Cell Respiration. Breathing and Cell Respiration are related. BREATHING. O 2. CO 2. Lungs. Muscle cells carrying out. CO 2. Bloodstream. O 2.

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Chapter 9 How Cells Harvest Chemical Energy

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  1. Chapter 9 How Cells Harvest Chemical Energy Introduction to Cell Metabolism Glycolysis Aerobic Cell Respiration Anaerobic Cell Respiration

  2. Breathing and Cell Respiration are related BREATHING O2 CO2 Lungs Muscle cells carrying out CO2 Bloodstream O2 CELLULAR RESPIRATION Sugar + O2 ATP + CO2 + H2O

  3. Cellular Respiration uses oxygen and glucose to produce Carbon dioxide, water, and ATP. Glucose Oxygen gas Carbon dioxide Water Energy

  4. How efficient is cell respiration? Energy released from glucose banked in ATP Energy released from glucose (as heat and light) Gasoline energy converted to movement 100% About 40% 25% Burning gasolinein an auto engine Burning glucose in an experiment “Burning” glucosein cellular respiration

  5. Reduction and Oxidation OILRIG Oxidation is losing electrons Reduction is gaining electrons Loss of hydrogen atoms Energy Glucose Gain of hydrogen atoms Glucose gives off energy and is oxidized

  6. Reduction and Oxidation OILRIG Gain or loss of electrons is often in the form of hydrogen. The hydrogen is then passed to a coenzyme such as NAD+

  7. Reduction and Oxidation What are some common co-enzymes? NAD+ and FAD NAD+ + 2 H  NADH + H+ FAD + 2 H  FADH2 Remember that H = 2 electrons and 2H+

  8. Reduction and Oxidation These co-enzymes are very important for cell respiration because they transfer high-energy electrons to electron transport systems (ETS).

  9. Reduction and Oxidation As the electrons move from carrier to carrier, energy is released in small quantities. Electron transport system (ETS)

  10. Generation of ATP There are two ways to generate ATP Chemiosmosis Substrate-Level Phosphorylation

  11. Generation of ATP Chemiosmosis Cells use the energy released by “falling” electrons in the ETS to pump H+ ions across a membrane Uses the enzyme ATP synthase.

  12. Generation of ATP Chemiosmosis

  13. Generation of ATP Substrate Level Phosphorylation Enzyme ATP can also be made by transferring phosphate groups from organic molecules to ADP Adenosine substrate Adenosine product Figure 6.7B

  14. Generation of ATP Substrate Level Phosphorylation Enzyme ATP can also be made by transferring phosphate groups from organic molecules to ADP Adenosine substrate Adenosine product Figure 6.7B

  15. General Outline • Glucose Glycolysis No Oxygen Anaerobic Oxygen Aerobic Pyruvic Acid Transition Reaction Fermentation Krebs Cycle ETS 38 ATP

  16. Glycolysis Where? The cytosol What? Breaks down glucose to pyruvic acid

  17. Steps – A fuelmolecule is energized,using ATP. Glucose 1 3 Step Glycolysis 1 Glucose-6-phosphate 2 Fructose-6-phosphate Energy In: 2 ATP 3 Fructose-1,6-diphosphate Step A six-carbonintermediate splits into two three-carbon intermediates. 4 4 Glyceraldehyde-3-phosphate (G3P) (TRIOSE PHOSPHATE) 5 Step A redoxreaction generatesNADH. 5 1,3-Diphosphoglycerate(2 molecules) 6 Steps – ATPand pyruvic acidare produced. 3-Phosphoglycerate(2 molecules) Energy Out: 4 ATP 6 9 7 2-Phosphoglycerate(2 molecules) 8 2-Phosphoglycerate(2 molecules) NET 2 ATP 9 Pyruvic acid (2 moleculesper glucose molecule)

  18. General Outline • Glucose Glycolysis No Oxygen Anaerobic Oxygen Aerobic Pyruvic Acid Transition Reaction Fermentation Krebs Cycle ETS 36-38 ATP

  19. General Outline of Aerobic Respiration • Glycolysis Transition Reaction Krebs Cycle Electron Transport System

  20. Transition Reaction/Pre-Krebs/Link Reaction: Occurs in the Matrix Each pyruvic acid molecule is broken down to form CO2 and a two-carbon acetyl group, which enters the Krebs cycle. An Oxidative Decarboxylation Reaction: Pyruvic Acid Acetyl CoA

  21. General Outline of Aerobic Respiration • Glycolysis Transition Reaction Krebs Cycle Electron Transport System

  22. Krebs Cycle Where? In the Mitochondria What? Uses Acetyl Co-A to generate ATP, NADH, FADH2, and CO2.

  23. Krebs Cycle

  24. Krebs Cycle

  25. General Outline of Aerobic Respiration • Glycolysis Krebs Cycle Electron Transport System

  26. Electron Transport System Proteincomplex Intermembranespace Electroncarrier Innermitochondrialmembrane Electronflow Mitochondrialmatrix ELECTRON TRANSPORT CHAIN ATP SYNTHASE Figure 6.12

  27. Electron Transport System

  28. CHEMIOSMOSIS • The coupling of ATP synthesis to electron transport via a concentration gradient. • It is the MECHANISM for oxidative phosphorylation in Aerobic C.R. and Photosynthesis

  29. Electron Transport System For each glucose molecule that enters cellular respiration, chemiosmosis produces up to 38 ATP molecules

  30. Overview of Aerobic Respiration

  31. General Outline • Glucose Glycolysis No Oxygen Anaerobic Oxygen Aerobic Pyruvic Acid Transition Reaction Fermentation Krebs Cycle ETS 38 ATP

  32. Fermentation Requires NADH generated by glycolysis. Where do you suppose these reactions take place? Yeast produce carbon dioxide and ethanol Muscle cells produce lactic acid Only a 2 ATP are produced per glucose

  33. Fermentation

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