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Bioenergetics

Bioenergetics. Components of a typical cell. Cellular Structures. Cell membrane semi-permeable encloses internal components of cell regulates flux of metabolites and nutrients Nucleus contains genetic material (DNA) regulates protein production Cytoplasm

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Bioenergetics

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  1. Bioenergetics

  2. Components of a typical cell

  3. Cellular Structures • Cell membrane • semi-permeable • encloses internal components of cell • regulates flux of metabolites and nutrients • Nucleus • contains genetic material (DNA) • regulates protein production • Cytoplasm • fluid portion of the cell which contains organelles, enzymes etc.

  4. Mitochondria • “power station” for the cell • All “aerobic” respiration takes place within the mitochondria • “anaerobic” glycolysis occurs in the cytoplasm

  5. ATP Generation • The purpose of glycolysis and aerobic respiration is to produce ATP • All of the systems we study in Exercise Physiology relate to ATP production

  6. ADP and ATP structures

  7. ATP as universal energy donor that drives energy needs of cells

  8. Breakdown of glucose to CO2 + H2O via cellular oxidation releases energy (Big Picture)

  9. The First Step

  10. Glycolysis: part 1

  11. glycolysis: part 2

  12. Glycolysis Yields Potential and Direct Energy • The glycolytic process yields NADH from NAD+ • NADH transported into mitochondria to produce ATP in electron transport • Glycolysis also yields ATP directly by “substrate level phosphorylation”

  13. Substrate Level Phosphorylation

  14. Production of Lactate

  15. Why Produce Lactate?

  16. glucose is broken down to pyruvate pyruvate can then enter the Krebs Cycle (aerobic) or pyruvate can form lactate (lactic acid) anaerobic, feel the burn Fate of Glucose (Glycolysis)

  17. The Krebs Cycle

  18. pyruvate enters the Krebs from glycolysis fatty acids also enter the Krebs cycle together pyruvate and fatty acids drive the Krebs to produce a lot of ATP The Krebs Cycle

  19. Krebs in Detail

  20. Electrons enter respiratory chain from glycolysis and Krebs

  21. Electron transport

  22. Electron transport 1

  23. Electron transport 2

  24. Chemiosmotic theory of aerobic ATP production

  25. Movement of protons across membrane and electrons along ETC • Animation of Electron transport in Mitochondria.htm

  26. A high proton gradient enables ATP to be generated

  27. Movement of protons through ATPase generates ATP • Animation of ATP synthesis in Mitochondria.htm

  28. ATP tally from breakdown of 1 glucose molecule

  29. Glycolysis occurs in the cytosol Glycolysis feeds the Krebs cycle Krebs occurs in the mitochondria Putting it together

  30. Pathways of Catabolism

  31. Energy Transformation • Exergonic vs. endergonic rxns • exergonic produces energy • endergonic requires energy input • Coupled rxns • by coupling exergonic rxn, energy can run endergonic rxn

  32. Coupling exergonic and endergonic reactions

  33. The energy systems • Anaerobic vs aerobic systems • Anaerobic (non-oxidative) • ATP-PC (Phosphocreatine or phosphagen) • PC + ADP => ATP + C • Glycolysis • breakdown of glucose to form 2 pyruvate or lactate • Aerobic • Krebs Cycle (TCA or oxidative phosphorylation)

  34. The Phosphocreatine (PC) System

  35. Phosphogen Reactions PCr + ADP + H+ <=> ATP + Cr Creatine Kinase ADP + ADP <=> ATP + AMP Adenylate Kinase

  36. Phosphagen System as Bioenergetic Regulator • Phosphagen system produces ATP at high rate to maintain energy state

  37. Enzymes • necessary for almost all biological processes • lower Energy of Activation • work in a “lock and key” type of mechanism • very sensitive to temperature and pH • remember body temp regulated in narrow range

  38. Enzymes catalyze reactions by lowering energy of activation

  39. Lock and Key model of enzyme action

  40. enzymes catalyze reactions by bringing the reactants into close proximity this means less energy is required to activate the reaction Take Home Message

  41. Fuels for Exercise • Carbohydrates • Fats • Proteins

  42. Carbohydrates-”A quick fix” • Simple sugars • glucose, fructose, sucrose, maltose • Complex carbs (polysaccharides) • starch, cellulose, glycogen • storage form of glucose is glycogen • Glycogenolysis • process by which glycogen is broken down into glucose for use by the body

  43. Fats-”Energy for the long haul” • More efficient storage form of energy than CHO (9 kcal/gram vs 4 kcal/gram) • Kinds of fats • fatty acids, triglycerides, phospholipids, steroids • Fatty acids and triglycerides are used for energy • Phospholipids and steroids are used for structural and regulatory purposes

  44. Proteins-”The building blocks” • Composed of sub-units called amino acids • Primarily used for structural purposes (muscle tissue, tendons, ligaments) • Also serve as enzymes • Can be used for energy (4 kcal/gram), but not readily

  45. Metabolism of Proteins, Carbohydrates and Fats

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