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Metabolism. Chapter 25b. Metabolism. The sum total of the chemical processes that occur in living organisms, resulting in growth, production of energy, elimination of waste material, etc. Anabolism - build up of complex molecules Catabolism - break down of complex molecules.

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  1. Metabolism Chapter 25b

  2. Metabolism • The sum total of the chemical processes that occur in living organisms, resulting in growth, production of energy, elimination of waste material, etc. • Anabolism- build up of complex molecules • Catabolism- break down of complex molecules

  3. ORGANIC BUILDING BLOCK MOLECULES Monosaccharides Amino acids Acetates Nucleotide bases Fates of Organic Building Blocks in ATP Metabolism ATP catabolic processes energy energy anabolic processes ADP+Pi Polymers & other energy rich molecules CO2 & H2O

  4. Cellular Respiration C6H12O6 + 6O2 + 36ADP + 36Pi 6CO2 + 6H2O + 36ATP

  5. Glycolysis Acetyl CoA Formation Krebs Cycle Electron Transport System Basic Steps Involved 1 2 3 4

  6. Overview of Glycolysis

  7. Fats Glycogen Protein Other Metabolic Pathways

  8. Glucose C C C C C C Glycolysis 2 ATP 2 ADP 2 PGAL C C C C C C P P 2 NAD+ 4 ADP 4 ATP 2 NADH 2 Pyruvate C C C • Net: • 2 ATP • 2 NADH • 2 Pyruvate molecules

  9. Balance Sheet for Glycolysis • Input 1 Glucose 2 ADP + Pi 2 NAD+ • Output 2 Pyruvate 2 ATP 2 NADH

  10. Transition Reaction

  11. Krebs Cycle (Citric Acid Cycle) Transition Reaction

  12. Krebs Cycle (Citric Acid Cycle)

  13. Balance Sheet for the Transition Reaction and Krebs Cycle • Input 2 Pyruvate 2 ADP + 2 Pi 8 NAD+ 2 FAD • Output 6 CO2 2 ATP 8 NADH 2 FADH2

  14. Krebs Cycle Handles other substrates Intermediate molecules used: proteins and lipids Replenishment of intermediates necessary Hans Krebs (1937): paper originally rejected

  15. Krebs Cycle Takes 2 complete cycles 8 steps, each with an enzyme

  16. 3 Krebs Cycle

  17. Oxidative Phosphorylation Chemiosmosis Electrons are transferred from complex to complex and some of their energy is used to pump protons (H+) into the intermembrane space, creating a proton gradient. ATP synthesis is powered by the flow of H+ back across the inner mitochondrial membrane through ATP synthase.

  18. Each Glucose Molecule CO2 6 NADH 10 FADH2 2 ATP 4

  19. Electron Transport System CO2 6 NADH 10 FADH22 ATP 4 used to make ATP

  20. 4 Electron Transport System

  21. Electron Transport System

  22. +Pi

  23. Electron Transport Chain and Oxidative Phosphorylation • Electrons are delivered to O, forming O– • O– attracts H+ to form H2O

  24. NADH+H+ Electron trans- port chain and oxidative phosphorylation Glycolysis Krebs cycle FADH2 Enzyme Complex II Enzyme Complex I Enzyme Complex III Free energy relative to O2 (kcal/mol) Enzyme Complex IV Figure 24.9

  25. Electronic Energy Gradient • Transfer of energy from NADH + H+ and FADH2 to oxygen releases large amounts of energy • This energy is released in a stepwise manner through the electron transport chain

  26. ATP Synthase • Two major parts connected by a rod • Rotor in the inner mitochondrial membrane • Knob in the matrix • Works like an ion pump in reverse

  27. Intermembrane space A rotor in the membrane spins clockwise when H+ flows through it down the H+ gradient. A stator anchored in the membrane holds the knob stationary. As the rotor spins, a rod connecting the cylindrical rotor and knob also spins. The protruding, stationary knob contains three catalytic sites that join inorganic phosphate to ADP to make ATP when the rod is spinning. ADP + Mitochondrial matrix Figure 24.11

  28. ATP Net ATP Yield 34 to 36 molecules ATP for every glucose molecule about 40% efficiency

  29. Transition cycle

  30. Overall ATP Production Electron Transport System 34 Citric Acid Cycle 2 Glycolysis 2 SUBTOTAL 38 NADH Transport into Mitochondrion* -2 TOTAL 36

  31. Fermentation (Anaerobic Respiration)

  32. Lactic Acid Fermentation NAD+ NAD+ NADH NADH C C C C C C C C C C C C (Glycolysis) (Lactic acid fermentation) Glucose 2 Pyruvate 2 Lactic Acid

  33. Glucose Anaerobic Respiration Aerobic Respiration Pyruvate no O2 O2 Acetyl CoA Ethanol or Lactate Krebs Cycle

  34. INQUIRY • What is the end product in glycolysis? • What substance is produced by the oxidation of pyruvate and feeds into the citric acid cycle? • Name a product of fermentation. • What role does O2 play in aerobic respiration? • What stage during cellular respiration is the most ATP synthesized? • What is chemiosmosis? • When NAD+ and FAD+ are reduced what do they form? • What are they used for?

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