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Lecture 1 bioenergetics
- 2. Objectives • Describe the basic concept of bioenergetics • Describe three major energy substrates and energy systems • Understand the differences of each energy system • Understand chemical reactions and metabolisms of each energy system • Understand the interaction among the three energy systems with respect to intensity and duration differences
- 3. • For any physical activity, energy must be made and used by the body to accomplish the task (work). • The study of energy flow in living organisms • How is that energy generated and ultimately utilized?
- 4. Energy Systems • ATP-PCr System • Specifics • Rate limiting Enzyme • Role during Exercise • Glycolytic System • Specifics • Rate limiting Enzyme • Role during Exercise • Oxidative System • Specifics • TCA Cycle • Rate limiting Enzyme • Electron Transport Chain • Role during Exercise • Lipid Metabolism • Beta Oxidation • Interaction of Energy Systems
- 5. ATP (adenosine triphosphate) ATP = body’s “energy source” Breaking phosphate bonds through chemical reactions (ATP hydrolysis) releases energy Energy used for muscle contraction and movement How does our body make ATP?? Energy
- 6. Anaerobic vs. Aerobic ATP produced through anaerobic and aerobic energy systems Anaerobic Aerobic Also called.. Non-oxidative, Glycolytic Oxidative Type of exercise High-intensity Low-Moderate Intensity Duration Short duration (<2 min) Longer duration (>2 min) Oxygen Does Not Require Oxygen Requires Oxygen Energy Systems ATP-PC; Anaerobic Glycolysis Oxidative Phosphorylation Energy Production High Rate Low Capacity Low Rate High Capacity
- 8. Control of ATP-PC System Activate Inhibit Creatine Kinase (Rate limiting enzyme)
- 9. Exercise and the ATP-PC System Power Exercise Example Shot Put Fuel Storage Site Cytosol ATP Reformation Rate Very Rapid Storage Form ATP, PC Activity Duration 0-3 sec
- 10. Glycolytic System • Glycogen (in liver/muscle) or Glucose (in blood) act as initial substrate • Energy Investment Phase (use 1 or 2 ATP) • Energy Generation Phase (make 4 ATP) • End product is Pyruvic acid (pyruvate) which is converted to Lactic Acid (lactate)
- 11. 2 Phases of Glycolysis Energy Investment phase • Requires 2 ATP Energy Generation phase • Produces 4 ATP, 2 NADH, 2 pyruvate or 2 lactate
- 13. Energy Investment Phase cont’ Fructose-1,6-Diphosphate 2(Glyceraldehye- 3-Phosphate) Dihydroxyacetone Phosphate 4 5 To Energy Generation Phase
- 15. Energy Generation Phase NAD+ NADH+H+ ADP ATP 2(Glyceraldehye-3-Phosphate) H2O 2(1,3 Diphosphoglycerate) 6 2(3-Phosphoglycerate) 7 2(2-Phosphoglycerate) 8 2(Phosphoenolpyruvate) 9
- 16. Energy Generation Phase Cont’ 2(Phosphoenolpyruvate) 2(Lactic Acid) 11 2(Pyruvic Acid) 10 NADH+H+ NAD+ Lactate Dehydrogenase ADP ATP Pyruvate Kinase
- 17. Energy Generation Phase (2 ATP) Figure 3.15 Glycolysis
- 18. Net Equation for Glycolysis
- 19. Control of Glycolytic System Activate Inhibit Phosphofructokinase (PFK) (Rate limiting enzyme)
- 20. Glycogen vs. Glucose Glycogen ATP ADPPhosphofructokinase Glucose-1-Phosphate Fructose-6-Phosphate Fructose-1,6-Diphosphate Glucose-6-Phosphate No ATP cost! Glucose ATP ADP
- 21. Exercise and Glycolytic System Speed Exercise Example 100-400m run, Basketball Fuel Storage Site Cytosol ATP Reformation Rate Rapid Storage Form Muscle Glycogen Activity Duration 4-50 sec
- 22. Anaerobic Glycolysis vs. Oxidative Phosphorylation • In the absence of oxygen, pyruvate is converted to lactate • In the presence of oxygen, pyruvate is shuttled into the mitochondria and begin the Citric Acid Cycle • TCA Cycle/Krebs Cycle
- 24. TCA Cycle Facts • Also known as the Krebs Cycle • Pyruvate from Glycolysis is shuttled into the mitochondria to start the reaction. • Cycle is made up of 8 distinct reactions. • Two cycles are completed per G-6-P molecule broken down in Glycolysis.
- 27. Control of TCA Cycle Isocitrate Dehydrogenase (Rate limiting enzyme) NADH ATP Inhibit ADP, Pi NAD+, Ca++ Activate
- 29. Electron Transport Chain (ETC) Basics • Dictated by the Chemiosmotic Theory. (movement of ions across a selectively permeable membrane, down their electrochemical gradient) • Physically Attached to Cristae of Mitochondria. • Composed of Complex I-IV, CoQ, Cytochromes, and F-complex (ATP Synthase). • Multiple ETCs in each mitochondria.
- 30. Chemiosmotic Theory • Transfer of electrons (e-) along protein complexes (enzymes and cytochromes) and pumps protons (H+). • Pumped protons create an energy gradient. • Energy gradient is used to re-synthesize ATP from ADP+Pi.
- 31. 1 3 2 4 Intermembrane Space Matrix NADH NAD+ 2H + 2H + 1H + FADH2 FAD2H + 1H + Outer Membrane Inner membrane Matrix Intermembrane Space
- 32. Proton Gradient 2 H+ 1 H+ FADH2 2 H+ 2 H+ 1H+ NADH NADH = 5 H+ FADH2 = 3 H+ 2 H+ ADP + Pi ATP F-Complex NADH = 2.5 ATP FADH2 = 1.5 ATP Phosphorylation
- 33. Oxygen Utilization Site ½ O2 H2O Intermembrane Space Matrix 2 4 Electron acceptor 2H+ + 2e- Oxidation
- 35. Chemiosmotic Hypothesis Pumping of H+ results in H+ gradient across membrane Movement of H+ ions through channel activates the enzyme ATP synthase http://www.youtube.com/watch?v=3y1dO4nNaKY
- 36. Amount of ATP per NADH/FADH 2 H+ 2 H+ 1 H+ 2 H+ needed to produce and transport 1 ATP NADH: 5 H+/2 H+ per ATP = 2.5 ATP FADH: 3 H+/2 H+ per ATP = 1.5 ATP
- 37. Tally of ATP Production Process Product Total ATP Pyruvate Acetyl-CoA 2 NADH TCA Cycle 2 GTP 6 NADH 2 FADH2 2 5 Glycolysis 2 ATP 2 NADH 5 2 15 3 TOTAL = 32 / Glucose (2 ATP) (2.5 ATP per 1 NADH) (1.5 ATP per 1 FADH2)
- 38. Exercise and Oxidative System Endurance Exercise Example >1500m run Fuel Storage Site Cytosol, blood, liver, fat ATP Reformation Rate Very Slow Storage Form Glycogen, lipids, amino acids Activity Duration >2 min
- 39. Maximal Duration of Energy System 30 sec 1 min 3 min 5 min 2-3 hr %Contribution ATP-PC Glycolysis Oxidative 10 sec
- 41. Lipid Metabolism Three types of Lipids: 1) Fatty Acids 2) Triglycerides (storage form) 3) Phospholipids • Requires more Oxygen and generates more ATP than Carbohydrate metabolism • Lean individual can store ~75,000 kcal of energy as Triglycerides. • Lean individual can store ~2,500 kcal of energy as Glycogen.
- 42. Triglyceride Lipolysis • Catalyzed by the enzyme Hormone-Sensitive Lipase. • FFA released into blood. • Transported to muscle cells based on concentration gradient. Fatty Acid Fatty Acid Fatty Acid Glycerol
- 43. Fatty Acids • Carboxylic acid with long aliphatic tail (chain) • Mostly natural FA has even number of carbon atoms, from 4 to 28
- 44. Beta Oxidation of Fatty Acids • Occurs in the Matrix of the Mitochondria. • 4 distinct reactions. • Final product is a Fatty Acid (shortened by two carbons) and Acetyl-CoA. • Acetyl-CoA enters the TCA cycle, and Fatty Acid undergoes another round of Beta- Oxidation. Series of steps in which two-carbon acyl units are chopped off of the carbon chain of the FFA
- 45. Acetyl- CoA Saturated Fatty Acid Product 3 Product 2 Product 1 FAD FADH2 NAD+ NADH Acyl-CoA Dehydrogenase Enoyl-CoA Hydratase Hydroxyacyl-CoA Dehydrogenase Thiolase Beta Oxidation of Fatty Acids
- 46. ATP Tally for Palmitic Acid (16 C) Start Beta- Oxidation Product ATP Value - 2 ATP - 2 7 Cycles of Beta- Oxidation 7 NADH 7 FADH2 17.5 10.5 8 TCA Cycles 24 NADH 8 FADH2 8 GTP 60 12 8 Grand Total = 106 ATP For Activation (2.5 ATP per 1 NADH) (1.5 ATP per 1 FADH2)
- 47. Beta Oxidation during Exercise Used to produce ATP: 1. At rest in exercise trained individuals. 2. When exercise intensity is low (< 40% max effort) 3. When Glycogen is not abundant (end of long duration exercise) Its response is mediated by the “Crossover Effect”
- 48. Crossover Effect % of max %Utilization CHO Fat35-40% of VO2 max
Notas del editor
- Bio (living organisms) + energetics (study of energy) Three major energy substrates are carbohydrate, fat, and protein. Not real energy About making and using energy
- In human, actual energy source is ATP. Three major energy systems in making ATP Fat metabolism How do energy systems interact with exercise intensity and exercise duration?
- Adenosine = Adenine (nitrogen containing base) + ribose (five-carbon sugar) Inorganic Phosphate ATP hydrolysis by ATPase (adenosine triphosphatase; ATPase) – about 7 to 10kcal per mole of ATP
- Different properties
- The simplest and fastest energy system to make ATP Catalyzed by creatine kinase
- Chemical reaction is controlled by rate limiting enzyme and negative feedback mechanism. i.e., Intense exercise
- Exercise requiring high power generation Shot Put - track and field Clean and Jerk - weight lifting Pitching and Bating - baseball
- ATP-PCr System – limited amount of ATP produced Glycolytic System – more complex pathway than the ATP-PCr system
- Keys Use ATP - Number 1-5 : steps body used ATP in ATP production pathway 2. Enzyme is involved with each step (reactant/temperature/pH – affect enzyme activity) 3. Phosphofuctokinase (rate limiting enzyme)
- One molecule of glucose generates two molecule of Glyceraldehye-3-Phosphate From this step, every reaction produced two molecules.
- Step 6 to 9: One ATP or Two ATPs produced? NAD: enzyme cofactor (coenzyme) Two NADH and H+ are produced Two H2O are produced
- Step 10-11 Two ATPs produced In condition without oxygen, pyruvic acid is catalized by lactate dehydrogenase to produce lactic acid. NADH and H+ are used for this reaction. Lactic acid - a acid causing muscle fatigue - inhibit prolonged activity or exercise
- One molecule of glucose makes two ATPs, lactates, and H2O
- Energy Investment Phase
- Applied in exercise Need high ATP very fast Limited capacity
- Glycolysis is not separate from oxidative phosphorylation. tricarboxylic acid cycle (TCA cycle)
- Power Plant to produce ATP Outer membrane Inter membrane Intermembrane space Matrix and cristae
- Two cycle – because one molecule of glucose produce two molecules of pyruvate
- First product is Acetyl-coA NAD is reduced to NADH and H+
- 3 NADH and 3 H+ are produced 1 FADH2 GTP, a type of ATP is also produced.
- Glycolysis and Krebs Cycle ATP 4 NADH 10 FADH 2
- Crossover point is the exercise intensity at which an individual shifts from using primarily fat metabolism to using primarily carbohydrate metabolism. High Intensity – require ATP fast – CHO is better Long term exercise – require prolonged ATP – Fat is better.