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Chapter 19 Bioenergetics

Chapter 19 Bioenergetics. How the Body Converts Food to Energy. ENERGY. 1 st Law of Thermodynamics Energy can’t be created or destroyed, it can only change forms. chemical → mechanical. chemical → electrical. electrical → mechanical. heat → mechanical.

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Chapter 19 Bioenergetics

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  1. Chapter 19 Bioenergetics How the Body Converts Food to Energy.

  2. ENERGY • 1st Law of Thermodynamics • Energy can’t be created or destroyed, it can only change forms. chemical → mechanical chemical→ electrical electrical → mechanical heat → mechanical

  3. Photosynthesis 6 CO2 + 6H2O + energy→ C6H12O6 + 6O2

  4. Lipids (fats) • Carbohydrates (sugar) • Protein

  5. Metabolism • Metabolism: the sum of all chemical reactions involved in maintaining the dynamic state of a cell or organism. • Pathway: a series of biochemical reactions. • Catabolism: the biochemical pathways that are involved in generating energy by breaking down large nutrient molecules into smaller molecules with the concurrent production of energy. • Anabolism: the pathways by which biomolecules are synthesized.

  6. Metabolism • Metabolism is the sum of catabolism and anabolism.

  7. CATABOLISM OF FOOD

  8. Common Catabolic Pthwy • The two parts to the common catabolic pathway: • The citric acid cycle, also called the tricarboxylic acid (TCA) or Krebs cycle. • Electron transport chain andphosphorylation, together called oxidative phosphorylation. • Four principal compounds participating in the common catabolic pathway are: • AMP, ADP, and ATP • NAD+/NADH • FAD/FADH2 • coenzyme A; abbreviated CoA or CoA-SH

  9. MITOCHONDRIA

  10. ATP = Adenosine Triphosphate

  11. 7.3 kcal 7.3 kcal ATP→ ADP + P + energy ADP + P + energy → ATP

  12. Nicotinamide adenine dinucleotide (NAD) Flavin adenine dinucleotide (FAD)

  13. NAD+/NADH • NAD+ is a two-electron oxidizing agent, and is reduced to NADH. • NADH is a two-electron reducing agent, and is oxidized to NAD+. • NADH is an electron and hydrogen ion transporting molecule.

  14. FAD/FADH2 • FAD is a two-electron oxidizing agent, and is reduced to FADH2. • FADH2 is a two-electron reducing agent, and is oxidized to FAD.

  15. Coenzyme A • The structure of coenzyme A.

  16. CITRIC ACID CYCLE

  17. Oxidative Phosphorylation • Carried out by four closely related multisubunit membrane-bound complexes and two electron carriers, coenzyme Q and cytochrome c. • In a series of oxidation-reduction reactions, electrons from FADH2 and NADH are transferred from one complex to the next until they reach O2. • O2 is reduced to H2O. • As a result of electron transport, protons are pumped across the inner membrane to the intermembrane space.

  18. ELECTRON TRANSPORT CHAIN

  19. CHEMIOSMOSIS

  20. Flow of e-

  21. The Energy Yield • For each two-carbon acetyl unit entering the citric acid cycle, we get three NADH and one FADH2. • For each NADH oxidized to NAD+, we get three ATP. • For each FADH2 oxidized to FAD, we get two ATP. • Thus, the yield of ATP per two-carbon acetyl group oxidized to CO2 is:

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