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Bioenergetics

Explore the components of a typical cell, from the cell membrane to the nucleus and cytoplasm, and learn how ATP generation, glycolysis, Krebs Cycle, and energy transformation drive cellular functions. Discover the importance of enzymes, bioenergetic systems, and the metabolism of carbohydrates, fats, and proteins in fueling cellular processes.

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

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

  8. The First Step

  9. Glycolysis: part 1

  10. glycolysis: part 2

  11. Substrate Level Phosphorylation

  12. Production of Lactate

  13. 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)

  14. The Krebs Cycle

  15. 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

  16. Krebs in Detail

  17. Electrons enter respiratory chain from glycolysis and Krebs

  18. Electron transport

  19. Electron transport 1

  20. Electron transport 2

  21. Chemiosmotic theory of aerobic ATP production

  22. Movement of protons across membrane and electrons along ETC

  23. A high proton gradient enables ATP to be generated

  24. Movement of protons through ATPase generates ATP

  25. ATP tally from breakdown of 1 glucose molecule

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

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

  28. Coupling exergonic and endergonic reactions

  29. 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)

  30. The Phosphocreatine (PC) System

  31. Phosphogen Reactions PCr + ADP + H+ <=> ATP + Cr Creatine Kinase ADP + ADP <=> ATP + AMP Adenylate Kinase • Determines Energy State of Cell • Hi [ATP] = lo [ADP],[ AMP], [Pi] • Low [ATP]= Hi [ADP, [AMP], [Pi]

  32. Phosphagen System as Bioenergetic Regulator • Phosphagen system produces ATP at high rate to maintain energy state • Results in metabolites (AMP, Pi, ADP) which stimulate metabolism • Elevations in AMP and decrease in [ATP]/[ADP] ratio stimulate metabolism

  33. 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

  34. Enzymes catalyze reactions by lowering energy of activation

  35. Lock and Key model of enzyme action

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

  37. Fuels for Exercise • Carbohydrates • Fats • Proteins

  38. 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

  39. 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

  40. 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

  41. Metabolism of Proteins, Carbohydrates and Fats

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