Chapter 2 energetics

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Chapter 2 energetics

  1. 1. Metabolism: The sum of the chemical reactions in an organismA metabolic pathway is a sequence of enzymaticallycatalyzed chemical reactions in a cellMetabolic pathways are determined by enzymes
  2. 2. Catabolic and Anabolic Reactions Catabolism: Provides energy and building blocks for anabolism. (Break down) Anabolism: Uses energy and building blocks to build large molecules. (Synthesis)
  3. 3. Metabolism: the sum of Catabolism andAnabolism Oxidation: the loss or removal of electrons Reduction: the gain of electrons
  4. 4. Role of ATP in Coupling Reactions Figure 5.1
  5. 5. Oxidation-Reduction Reactions Oxidation: Removal of electrons Reduction: Gain of electrons Redox reaction: An oxidation reaction paired with a reduction reaction
  6. 6. Oxidation-Reduction Reactions In biological systems, the electrons are often associated with hydrogen atoms. Biological oxidations are often dehydrogenations
  7. 7. The Generation of ATP ATP is generated by the phosphorylation of ADP
  8. 8. Substrate-Level Phosphorylation Energy from the transfer of a high-energy PO4– to ADP generates ATP
  9. 9. Oxidative Phosphorylation Energy released from transfer of electrons (oxidation) of one compound to another (reduction) is used to generate ATP in the electron transport chain
  10. 10. Carbohydrate Catabolism The breakdown of carbohydrates to release energy  Glycolysis  Krebs cycle  Electron transport chain
  11. 11. Glycolysis The oxidation of glucose to pyruvic acid produces ATP and NADH Figure 5.11
  12. 12. Preparatory Stage of Glycolysis 2 ATP are used Glucose is split to form 2 glyceraldehyde-3-phosphate Figure 5.12, steps 1–5
  13. 13. Energy-Conserving Stage ofGlycolysis 2 glucose-3-phosphate oxidized to 2 pyruvic acid 4 ATP produced 2 NADH produced Figure 5.12, steps 6–10
  14. 14. The Reactions of Glycolysis
  15. 15. The Krebs Cycle Oxidation of acetyl CoA produces NADH and FADH2
  16. 16. The Krebs Cycle Figure 5.13
  17. 17. The Reactions of the Krebs Cycle
  18. 18. The Electron Transport Chain A series of carrier molecules that are, in turn, oxidized and reduced as electrons are passed down the chain Energy released can be used to produce ATP by chemiosmosis
  19. 19. Overview of Respiration andFermentation Figure 5.11
  20. 20. Chemiosmotic Generation of ATP Figure 5.16
  21. 21. An Overview of Chemiosmosis Figure 5.15
  22. 22. A Summary of Respiration Aerobic respiration: The final electron acceptor in the electron transport chain is molecular oxygen (O2). Anaerobic respiration: The final electron acceptor in the electron transport chain is not O2. Yields less energy than aerobic respiration because only part of the Krebs cycles operates under anaerobic conditions.
  23. 23. Respiration Figure 5.16
  24. 24. Carbohydrate Catabolism  Energy produced from complete oxidation of one glucose using aerobic respiration Pathway ATP Produced NADH FADH2 Produced ProducedGlycolysis 2 2 0Intermediate step 0 2 0Krebs cycle 2 6 2Total 4 10 2
  25. 25. Carbohydrate Catabolism ATP produced from complete oxidation of one glucose using aerobic respiration By Oxidative Phosphorylation Pathway By Substrate-Level Phosphorylation From NADH From FADHGlycolysis 2 6 0Intermediate step 0 6 0Krebs cycle 2 18 4Total 4 30 4
  26. 26. Carbohydrate Catabolism 36 ATPs are produced in eukaryotes By Oxidative Phosphorylation Pathway By Substrate-Level Phosphorylation From NADH From FADHGlycolysis 2 6 0Intermediate step 0 6Krebs cycle 2 18 4Total 4 30 4
  27. 27. Fermentation One process by which pyruvate is subsequently metabolized in the absence of oxygen The result of the need to recycle the limited amount of NAD by passing the electrons of reduced NAD to other molecules Homolactic acid fermentation: pyruvate is converted directly to lactic acid, using electrons from reduced NAD Alcoholic fermentation: carbon dioxide is released from pyruvate to form acetaldehyde, which is reduced to ethanol
  28. 28. Fermentation Any spoilage of food by microorganisms (general use) Any process that produces alcoholic beverages or acidic dairy products (general use) Any large-scale microbial process occurring with or without air (common definition used in industry)
  29. 29. Fermentation Scientific definition:  Releases energy from oxidation of organic molecules  Does not require oxygen  Does not use the Krebs cycle or ETC  Uses an organic molecule as the final electron acceptor
  30. 30. An Overview of Fermentation Figure 5.18a
  31. 31. Types of Fermentation Figure 5.19
  32. 32. Requirements of ATP Production Figure 5.27
  33. 33. A Nutritional Classification ofOrganisms Figure 5.28
  34. 34. A Nutritional Classification ofOrganisms Figure 5.28
  35. 35. A Nutritional Classification ofOrganisms Figure 5.28
  36. 36. Metabolic Diversity amongOrganisms Nutritional Type Energy Source Carbon Source ExamplePhotoautotroph Light CO2 Oxygenic: Cyanobacteria plants Anoxygenic: Green, purple bacteriaPhotoheterotroph Light Organic Green, purple nonsulfur compounds bacteriaChemoautotroph Chemical CO2 Iron-oxidizing bacteriaChemoheterotroph Chemical Organic Fermentative bacteria compounds Animals, protozoa, fungi, bacteria.

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