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Chapter 3 Bioenergetics

Chapter 3 Bioenergetics. EXERCISE PHYSIOLOGY Theory and Application to Fitness and Performance, 6 th edition Scott K. Powers & Edward T. Howley. Introduction. _____________________: total of all chemical reactions that occur in the body ___________________ reactions

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Chapter 3 Bioenergetics

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  1. Chapter 3Bioenergetics EXERCISE PHYSIOLOGY Theory and Application to Fitness and Performance, 6th edition Scott K. Powers & Edward T. Howley

  2. Introduction • _____________________: total of all chemical reactions that occur in the body • ___________________ reactions • Synthesis of molecules • ___________________ reactions • Breakdown of molecules • _____________________ • Converting foodstuffs (fats, proteins, carbohydrates) into energy

  3. Objectives • Discuss the function of cell membrane, nucleus, and mitochondria • Define: endergonic, exergonic, coupled reactions, and bioenergetics • Describe how enzymes work • Discuss nutrients used for energy • Identify high-energy phosphates

  4. Objectives • Discuss anaerobic and aerobic production of ATP • Describe how metabolic pathways are regulated • Discuss the interaction of anaerobic and aerobic ATP production during exercise • Identify the rate limiting enzymes

  5. Cell Structure • Remember>>>NOT ALL CELLS ARE ALIKE!! • _____________________________ • Protective barrier between interior of cell and extracellular fluid • 2 most important functions… 1. 2. • _____________________________ • Contains genes (DNA) that regulate protein synthesis • Function… 1. _______________________________, which determines cell composition and controls cellular activity

  6. Cell Structure • _________________________ • Fluid portion of cell • Contains organelles (mitochondria) • _________________________ 1. Powerhouse of the cell 2. Involved in the oxidative conversion of foodstuffs into energy

  7. _________________________________________________________ Fig 3.1 _________ _______ If this were a muscle cell it would be called the _____________________ Fig 3.1

  8. Cellular Chemical Reactions • ____________________________ • Require energy to be added to reactants before the reaction will proceed • Product contains more energy than the original reactant • ____________________________ • Release energy as a result of a chemical process • ____________________________ • Liberation of energy in an exergonic reaction drives an endergonic reaction

  9. The Breakdown of Glucose: An Exergonic Reaction Fig 3.3

  10. Coupled Reactions Fig 3.4

  11. Oxidation-Reduction Reactions • ____________________: removing an electron • ____________________: addition of an electron • Oxidation and reduction are always coupled reactions • WHY??? • _______________________________________________________________________________________________________________ • ____________________ • Donates the electron • ____________________ • Accepts the electron

  12. Oxidation-Reduction Reactions • T/F??? • The term oxidation means that O2 participates in the reaction • Oxidation-Reduction reactions in cells, often involve the transfer of hydrogen atoms rather than free electrons • Hydrogen atom contains one electron • A molecule that loses a hydrogen also loses an electron and, therefore, is oxidized • NAD – nicotinamide adenine dinucleotide (derived from niacin) – ______________ form • FAD – flavin adenine dinucleotide (derived from riboflavin) – ______________ form • NADH and FADH – __________________ form

  13. _________________ • Catalysts that regulate the speed of reactions • Do not cause a reaction to occur • Lower the energy of activation • The energy required to initiate chemical reactions • Fight over a girl or guy!!!

  14. Enzymes Lower the Energy of Activation Fig 3.6

  15. Enzyme-Substrate Interaction • Enzymes interact with specific substrates • Lock and key model Fig 3.7

  16. Enzymes • Factors that alter regular enzyme activity • __________________ • Optimal ________________ range • _____________________ • __________ • Optimal ________ range • ~7.5 – 8.0

  17. Temp. and pH Effect on Enzymes

  18. Fuels for Exercise • _________________________ • Glucose • Stored as glycogen • Where is it stored? 1. Muscle and liver • __________________________ • Primarily ________________________ • Stored as _____________________ • _________________________ • Not a primary energy source during exercise

  19. ATP ADP + Pi+ Energy ATPase High-Energy Phosphates • Adenosine triphosphate (___________) • Consists of adenine, ribose, and three linked phosphates • Formation • Breakdown ADP + Pi ATP

  20. Model of ATP as the Universal Energy Donor Fig 3.9

  21. Bioenergetics • Formation of ATP • Phosphocreatine (PC) breakdown • Degradation of glucose and glycogen (glycolysis) • Oxidative formation of ATP • Anaerobic pathways • ____________________ involve O2 • PC breakdown and glycolysis • Aerobic pathways • ____________________ O2 • Oxidative phosphorylation

  22. PC + ADP ATP + C Creatine kinase Anaerobic ATP Production • ATP-PC system • Immediate source of ATP • Glycolysis • Energy investment phase • Requires 2 ATP • Energy generation phase • Produces ATP, NADH (carrier molecule), and pyruvate or lactate

  23. Glycolysis Energy Investment Phase Fig 3.11

  24. Glycolysis Energy Generation Phase Fig 3.11

  25. Oxidation-Reduction Reactions • Oxidation • Molecule accepts electrons (along with H+) • Reduction • Molecule donates electrons • Nicotinomide adenine dinucleotide (NAD) • Flavin adenine dinucleotide (FAD) NAD + 2H+ NADH + H+ FAD + 2H+ FADH2

  26. How is NAD Reformed from NADH? 1. Sufficient O2: 2. Insufficient O2:

  27. Production of Lactic Acid • Normally, O2 is available in the _______________ to accept H+ (and electrons) from ______________ produced in glycolysis • In anaerobic pathways, O2 is not available • H+ and electrons from NADH are accepted by _____________ to form _____________

  28. Conversion of Pyruvic Acid to Lactic Acid Fig 3.12

  29. Aerobic ATP Production • Involves the interaction of 2 cooperating metabolic pathways 1. _______________ (___________________) • Completes the oxidation of substrates and produces NADH and FADH to enter the electron transport chain 2. _____________________________ • Oxidative phosphorylation • Electrons removed from NADH and FADH are passed along a series of carriers to produce ATP • H+ from NADH and FADH are accepted by O2 to form water

  30. Importance of H+ Removal • Contain the potential energy in food molecules by virtue of the ___________________ they possess

  31. The Krebs Cycle Fig 3.14

  32. Relationship Between the Metabolism of Proteins, Fats, and Carbohydrates If start with ___________ 2.5 ATP per NADH 1.5 ATP per FADH ___ ATP 6 Phosphate __NADH __ATP through ETC __ATP __ATP ___ ATP Net 2 ATP if start with glucose __NADH __ATP through ETC through ETC Glucose ___ATP Glycogen ___ATP __NADH __NADH __ATP __FADH __FADH __ATP __ATP __ATP

  33. Electron Transport Chain Fig 3.17

  34. The Chemiosmotic Hypothesis of ATP Formation • Electron transport chain results in pumping of H+ ions across inner mitochondrial membrane • Results in H+ gradient across membrane • Energy released to form ATP as H+ diffuse back across the membrane

  35. The Chemiosmotic Hypothesis of ATP Formation Fig 3.16

  36. Why is O2 Essential For the Aerobic Production of ATP? • Purpose of ETC is to move _________________ • Therefore, each element in ETC must undergo a series of ________________________ reactions • If the last molecule remained in a ____________ state it would not be able to accept more electrons • Thus, ETC would _____________ • When O2 is present the last molecule in the chain can be ________________ by O2 • Thus, O2 allows ETC to continue by functioning as the final ________________________ of ETC

  37. Efficiency of Oxidative Phosphorylation • Aerobic metabolism of one molecule of glucose • Yields _____ ATP • Aerobic metabolism of one molecule of glycogen • Yields _____ ATP • Overall efficiency of aerobic respiration is ______% • ______% of energy released as heat

  38. Control of Bioenergetics • ____________________________ • An enzyme that regulates the rate of a metabolic pathway • Levels of ATP and ADP+Pi • High levels of ATP ______ ATP production • Low levels of ATP and high levels of ADP+Pi ______________ ATP production • Calcium may ____________ aerobic ATP production

  39. Control of Metabolic Pathways Table 3.2

  40. PC + ADP C + ATP 1 Control of Bioenergetics Rate Limiting Enzymes 1. Creatine kinase 2. Phosphofructokinase 3. Iscitrate dehydrogenase 4. Cytochrome oxidase Glycogen ATP-PC System Glucose Glucose 6-phosphate 2 Glycolysis Phosphoglyceraldehyde Glycerol Triglycerides Lactic Acid Pyruvic Acid -ox Proteins Acetyl CoA Fatty acids Amino Acids Ketone bodies C6 Urea Krebs Cycle C4 Table 3.2 NADH FADH ETS 3 C5 4

  41. Interaction Between Aerobic and Anaerobic ATP Production • Energy to perform exercise comes from an interaction between aerobic and anaerobic pathways • Effect of duration and intensity • Short-term, high-intensity activities • Greater contribution of __________ energy systems • Long-term, low to moderate-intensity exercise • Majority of ATP produced from _________ sources

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