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Scott K. Powers Edward T. Howley Theory and Application to Fitness and Performance SEVENTH EDITION Chapter Copyright ©2009 The McGraw-Hill Companies, Inc.

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Presentation on theme: "Scott K. Powers Edward T. Howley Theory and Application to Fitness and Performance SEVENTH EDITION Chapter Copyright ©2009 The McGraw-Hill Companies, Inc."— Presentation transcript:

1 Scott K. Powers Edward T. Howley Theory and Application to Fitness and Performance SEVENTH EDITION Chapter Copyright ©2009 The McGraw-Hill Companies, Inc. Permission required for reproduction or display outside of classroom use. Bioenergetics

2 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Objectives 1.Discuss the functions of the cell membrane, nucleus, and mitochondria. 2.Define the following terms: (1) endergonic reactions, (2) exergonic reactions, (3) coupled reactions, and (4) bioenergetics. 3.Describe the role of enzymes as catalysts in cellular chemical reactions. 4.List and discuss the nutrients that are used as fuels during exercise. 5.Identify the high-energy phosphates.

3 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Objectives 6.Discuss the biochemical pathways involved in anaerobic ATP production. 7.Discuss the aerobic production of ATP. 8.Describe the general scheme used to regulate metabolic pathways involved in bioenergetics. 9.Discuss the interaction between aerobic and anaerobic ATP production during exercise. 10.Identify the enzymes that are considered rate limiting in glycolysis and the Krebs cycle.

4 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Outline  Cell Structure  Biological Energy Transformation Cellular Chemical Reactions Oxidation-Reduction Reactions Enzymes  Fuels for Exercise Carbohydrates Fats Proteins  High-Energy Phosphates  Bioenergetics Anaerobic ATP Production Aerobic ATP production  Aerobic ATP Tally  Efficiency of Oxidative Phosphorylation  Control of Bioenergetics Control of ATP-PC System Control of Glycolysis Control of Krebs Cycle and Electron Transport Chain  Interaction Between Aerobic/Anaerobic ATP Production

5 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Introduction Metabolism –Sum of all chemical reactions that occur in the body –Anabolic reactions  Synthesis of molecules –Catabolic reactions  Breakdown of molecules Bioenergetics –Converting foodstuffs (fats, proteins, carbohydrates) into energy

6 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Cell Structure Cell membrane –Semipermeable membrane that separates the cell from the extracellular environment Nucleus –Contains genes that regulate protein synthesis  Molecular biology Cytoplasm –Fluid portion of cell –Contains organelles  Mitochondria

7 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Cell Structure A Typical Cell and Its Major Organelles Figure 3.1

8 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. In Summary  Metabolism is defined as the total of all cellular reactions that occur in the body; this includes both the synthesis of molecules and the breakdown of molecules.  Cell structure includes the following three major parts: (1) cell membrane, (2) nucleus, and (3) cytoplasm (called sarcoplasm in muscle).  The cell membrane provides a protective barrier between the interior of the cell and the extracellular fluid.  Genes (located within the nucleus) regulate protein synthesis within the cell.  The cytoplasm is the fluid portion of the cell and contains numerous organelles Cell Structure

9 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. A Closer Look 3.1 Molecular Biology and Exercise Science Study of molecular structures and events underlying biological processes –Relationship between genes and cellular characteristics they control Genes code for specific cellular proteins –Process of protein synthesis Exercise training results in modifications in protein synthesis –Strength training results in increased synthesis of muscle contractile protein Molecular biology provides “tools” for understanding the cellular response to exercise Cell Structure

10 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Steps Leading to Protein Synthesis Figure DNA contains information to produce proteins. 2.Transcription produces mRNA. 3.mRNA leaves nucleus and binds to ribosome. 4.Amino acids are carried to the ribosome by tRNA. 5.In translation, mRNA is used to determine the arrangement of amino acids in the polypeptide chain. Biological Energy Transformation

11 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Biological Energy Transformation Cellular Chemical Reactions Endergonic reactions –Require energy to be added –Endothermic Exergonic reactions –Release energy –Exothermic Coupled reactions –Liberation of energy in an exergonic reaction drives an endergonic reaction

12 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. The Breakdown of Glucose: An Exergonic Reaction Figure 3.3 Biological Energy Transformation

13 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Biological Energy Transformation Figure 3.4 The energy given off by the exergonic reaction powers the endergonic reaction Coupled Reactions

14 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Oxidation-Reduction Reactions Oxidation –Removing an electron Reduction –Addition of an electron Oxidation and reduction are always coupled reactions Often involves 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 Importance of NAD and FAD Biological Energy Transformation

15 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Oxidation-Reduction Reaction Involving NAD and NADH Biological Energy Transformation Figure 3.5

16 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Enzymes Catalysts that regulate the speed of reactions –Lower the energy of activation Factors that regulate enzyme activity –Temperature –pH Interact with specific substrates –Lock and key model Biological Energy Transformation

17 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Enzymes Catalyze Reactions Biological Energy Transformation Figure 3.6 Enzymes lower the energy of activation

18 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. The Lock-and-Key Model of Enzyme Action Figure 3.7 a)Substrate (sucrose) approaches the active site on the enzyme. b)Substrate fits into the active site, forming enzyme- substrate complex. c)The enzyme releases the products (glucose and fructose). Biological Energy Transformation

19 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Clinical Applications 3.1 Diagnostic Value of Measuring Enzyme Activity in the Blood Biological Energy Transformation Damaged cells release enzymes into the blood –Enzyme levels in blood indicate disease or tissue damage Diagnostic application –Elevated lactate dehydogenase or creatine kinase in the blood may indicate a myocardial infarction

20 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Examples of the Diagnostic Value of Enzymes in Blood Biological Energy Transformation

21 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Biological Energy Transformation Classification of Enzymes Oxidoreductases –Catalyze oxidation-reduction reactions Transferases –Transfer elements of one molecule to another Hydrolases –Cleave bonds by adding water Lyases –Groups of elements are removed to form a double bond or added to a double bond Isomerases –Rearrangement of the structure of molecules Ligases –Catalyze bond formation between substrate molecules

22 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Example of the Major Classes of Enzymes Biological Energy Transformation

23 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Factors That Alter Enzyme Activity Temperature –Small rise in body temperature increases enzyme activity –Exercise results in increased body temperature pH –Changes in pH reduces enzyme activity –Lactic acid produced during exercise Biological Energy Transformation

24 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. The Effect of Body Temperature on Enzyme Activity Biological Energy Transformation Figure 3.8

25 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. The Effect of pH on Enzyme Activity Biological Energy Transformation Figure 3.9

26 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Carbohydrates Glucose –Blood sugar Glycogen –Storage form of glucose in liver and muscle  Synthesized by enzyme glycogen synthase –Glycogenolysis  Breakdown of glycogen to glucose Fuels for Exercise

27 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Fats Fatty acids –Primary type of fat used by the muscle –Triglycerides  Storage form of fat in muscle and adipose tissue  Breaks down into glycerol and fatty acids Phospholipids –Not used as an energy source Steroids –Derived from cholesterol –Needed to synthesize sex hormones Fuels for Exercise

28 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Fuels for Exercise Protein Composed of amino acids Some can be converted to glucose in the liver –Gluconeogenesis Others can be converted to metabolic intermediates –Contribute as a fuel in muscle Overall, protein is not a primary energy source during exercise

29 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. In Summary  The body uses carbohydrate, fat, and protein nutrients consumed daily to provide the necessary energy to maintain cellular activities both at rest and during exercise. During exercise, the primary nutrients used for energy are fats and carbohydrates, with protein contributing a relatively small amount of the total energy used.  Glucose is stored in animal cells as a polysaccharide called glycogen.  Fatty acids are the primary form of fat used as an energy source in cells. Fatty acids are stored as triglycerides in muscle and fat cells. Fuels for Exercise

30 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Adenosine triphosphate (ATP) –Consists of adenine, ribose, and three linked phosphates Synthesis Breakdown ADP + P i  ATP ADP + P i + EnergyATP ATPase High-Energy Phosphates

31 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Structure of ATP High-Energy Phosphates Figure 3.10

32 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Model of ATP as the Universal Energy Donor Figure 3.11 High-Energy Phosphates

33 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Bioenergetics Formation of ATP –Phosphocreatine (PC) breakdown –Degradation of glucose and glycogen  Glycolysis –Oxidative formation of ATP Anaerobic pathways –Do not involve O 2 –PC breakdown and glycolysis Aerobic pathways –Require O 2 –Oxidative phosphorylation Bioenergetics

34 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. ATP + C PC + ADP Creatine kinase Anaerobic ATP Production ATP-PC system –Immediate source of ATP Glycolysis –Glucose  2 pyruvic acid or 2 lactic acid –Energy investment phase  Requires 2 ATP –Energy generation phase  Produces 4 ATP, 2 NADH, and 2 pyruvate or 2 lactate Bioenergetics

35 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. The Winning Edge 3.1 Does Creatine Supplementation Improve Exercise Performance? Depletion of PC may limit short-term, high-intensity exercise Creatine monohydrate supplementation –Increased muscle PC stores –Some studies show improved performance in short- term, high-intensity exercise  Inconsistent results may be due to water retention and weight gain –Increased strength and fat-free mass with resistance training Creatine supplementation does not appear to pose health risks Bioenergetics

36 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. A Closer Look 3.2 Lactic Acid or Lactate? Terms lactic acid and lactate used interchangeably –Lactate is the conjugate base of lactic acid Lactic acid is produced in glycolysis –Rapidly disassociates to lactate and H + Figure 3.12 The ionization of lactic acid forms the conjugate base called lactate Bioenergetics

37 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. The Two Phases of Glycolysis Figure 3.13 Bioenergetics

38 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Interaction Between Blood Glucose and Muscle Glycogen in Glycolysis Figure 3.14 Bioenergetics

39 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Bioenergetics Figure 3.15 Glycolysis: Energy Investment Phase

40 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Glycolysis: Energy Generation Phase Bioenergetics Figure 3.15

41 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Transport hydrogens and associated electrons –To mitochondria for ATP generation (aerobic) –To convert pyruvic acid to lactic acid (anaerobic) Nicotinamide adenine dinucleotide (NAD) Flavin adenine dinucleotide (FAD) NAD + 2H +  NADH + H + FAD + 2H +  FADH 2 Hydrogen and Electron Carrier Molecules Bioenergetics

42 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. A Closer Look 3.3 NADH is “Shuttled” into Mitochondria NADH produced in glycolysis must be converted back to NAD –By converting pyruvic acid to lactic acid –By “shuttling” H + into the mitochondria A specific transport system shuttles H + across the mitochondrial membrane –Located in the mitochondrial membrane Bioenergetics

43 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Conversion of Pyruvic Acid to Lactic Acid Figure 3.16 The addition of two H + to pyruvic acid forms NAD and lactic acid Bioenergetics

44 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved.  The immediate source of energy for muscular contraction is the high-energy phosphate ATP. ATP is degraded via the enzyme ATPase as follows:  Formation of ATP without the use of O 2 is termed anaerobic metabolism. In contrast, the production of ATP using O 2 as the final electron acceptor is referred to as aerobic metabolism. In Summary ADP + P i + EnergyATP ATPase Bioenergetics

45 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved.  Exercising skeletal muscles produce lactic acid. However, once produced in the body, lactic acid is rapidly converted to its conjugate base, lactate.  Muscle cells can produce ATP by any one or a combination of three metabolic pathways: (1) ATP-PC system, (2) glycolysis, (3) oxidative ATP production.  The ATP-PC system and glycolysis are two anaerobic metabolic pathways that are capable of producing ATP without O 2. In Summary Bioenergetics

46 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Bioenergetics Aerobic ATP Production Krebs cycle (citric acid cycle) –Pyruvic acid (3 C) is converted to acetyl-CoA (2 C)  CO 2 is given off –Acetyl-CoA combines with oxaloacetate (4 C) to form citrate (6 C) –Citrate is metabolized to oxaloacetate  Two CO 2 molecules given off –Produces three molecules of NADH and one FADH –Also forms one molecule of GTP  Produces one ATP

47 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. The Three Stages of Oxidative Phosphorylation Figure 3.17 Bioenergetics

48 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. The Krebs Cycle Figure 3.18 Bioenergetics

49 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Bioenergetics Fats and Proteins in Aerobic Metabolism Fats –Triglycerides  glycerol and fatty acids –Fatty acids  acetyl-CoA  Beta-oxidation –Glycerol is not an important muscle fuel during exercise Protein –Broken down into amino acids –Converted to glucose, pyruvic acid, acetyl-CoA, and Krebs cycle intermediates

50 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Bioenergetics Figure 3.19 Relationship Between the Metabolism of Proteins, Carbohydrates, and Fats

51 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Aerobic ATP Production Electron transport chain –Oxidative phosphorylation occurs in the mitochondria –Electrons removed from NADH and FADH are passed along a series of carriers (cytochromes) to produce ATP  Each NADH produces 2.5 ATP  Each FADH produces 1.5 ATP –Called the chemiosmotic hypothesis –H + from NADH and FADH are accepted by O 2 to form water Bioenergetics

52 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Bioenergetics 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 + ions diffuse back across the membrane

53 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Figure 3.20 The Electron Transport Chain Bioenergetics

54 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. A Closer Look 3.4 Beta Oxidation is the Process of Converting Fatty Acids to Acetyl-CoA Breakdown of triglycerides releases fatty acids Fatty acids must be converted to acetyl-CoA to be used as a fuel –Activated fatty acid (fatty acyl-CoA) into mitochondrion –Fatty acid “chopped” into 2 carbon fragments forming acetyl-CoA Acetyl-CoA enters Krebs cycle and is used for energy Bioenergetics

55 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Beta Oxidation Figure 3.21 Bioenergetics

56 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved.  Oxidative phosphorylation or aerobic ATP production occurs in the mitochondria as a result of a complex interaction between the Krebs cycle and the electron transport chain. The primary role of the Krebs cycle is to complete the oxidation of substrates and form NADH and FADH to enter the electron transport chain. The end result of the electron transport chain is the formation of ATP and water. Water is formed by oxygen-accepting electrons; hence, the reason we breathe oxygen is to use it as the final acceptor of electrons in aerobic metabolism. In Summary Bioenergetics

57 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. A Closer Look 3.5 A New Look at the ATP Balance Sheet Historically, 1 glucose produced 38 ATP Recent research indicates that 1 glucose produces 32 ATP –Energy provided by NADH and FADH also used to transport ATP out of mitochondria. –3 H + must pass through H + channels to produce 1 ATP –Another H + needed to move the ATP across the mitochondrial membrane Aerobic ATP Tally

58 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Aerobic ATP Tally Per Glucose Molecule Aerobic ATP Tally

59 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. 32 moles ATP/mole glucose x 7.3 kcal/mole ATP 686 kcal/mole glucose x 100 = 34% Efficiency of Oxidative Phosphorylation One mole of ATP has energy yield of 7.3 kcal 32 moles of ATP are formed from one mole of glucose Potential energy released from one mole of glucose is 686 kcal/mole Overall efficiency of aerobic respiration is 34% –66% of energy released as heat

60 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved.  The aerobic metabolism of one molecule of glucose results in the production of 32 ATP molecules, whereas the aerobic yield for glycogen breakdown is 33 ATP.  The overall efficiency of aerobic of aerobic respiration is approximately 34%, with the remaining 66% of energy being released as heat. In Summary Efficiency of Oxidative Phosphorylation

61 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Control of Bioenergetics Rate-limiting enzymes –An enzyme that regulates the rate of a metabolic pathway Modulators of rate-limiting enzymes –Levels of ATP and ADP+P i  High levels of ATP inhibit ATP production  Low levels of ATP and high levels of ADP+P i stimulate ATP production –Calcium may stimulate aerobic ATP production Control of Bioenergetics

62 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Figure 3.22 Example of a Rate-Limiting Enzyme Control of Bioenergetics

63 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Factors Known to Affect Rate-Limiting Enzymes Control of Bioenergetics

64 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved.  Metabolism is regulated by enzymatic activity. An enzyme that regulates a metabolic pathway is termed a “rate-limiting” enzyme.  The rate-limiting enzyme for glycolysis is phosphofructokinase, while the rate-limiting enzymes for the Krebs cycle and electron transport chain are isocitrate dehydrogenase and cytochrome oxidase, respectively.  In general, cellular levels of ATP and ADP+P i regulate the rate of metabolic pathways involved in the production of ATP. High levels of ATP inhibit further ATP production, while low levels of ATP and high levels of ADP+P i stimulate ATP production. Evidence also exists that calcium may stimulate aerobic energy metabolism. In Summary Control of Bioenergetics

65 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Interaction Between Aerobic/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 anaerobic energy systems –Long-term, low to moderate-intensity exercise  Majority of ATP produced from aerobic sources Interaction Between Aerobic/Anaerobic ATP Production

66 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Interaction Between Aerobic/Anaerobic ATP Production Figure 3.23 The Winning Edge 3.2 Contribution of Aerobic/Anaerobic ATP Production During Sporting Events

67 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved.  Energy to perform exercise comes from an interaction of anaerobic and aerobic pathways.  In general, the shorter the activity (high intensity), the greater the contribution of anaerobic energy production. In contrast, long-term activities (low to moderate intensity) utilize ATP produced from aerobic sources. In Summary Interaction Between Aerobic/Anaerobic ATP Production

68 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Study Questions 1.List and briefly discuss the functions of the three major components of cell structure. 2.Briefly explain the concept of coupled reactions. 3.Define the following terms: (1) bioenergetics, (2) endergonic reactions, and (3) exergonic reactions. 4.Discuss the role of enzymes as catalysts. What is meant by the expression “energy of activation”? 5.Where do glycolysis, the Krebs cycle, and oxidative phosphorylation take place in the cell? 6.Define the terms glycogen, glycogenolysis, and glycolysis.

69 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Study Questions 7.What are the high-energy phosphates? Explain the statement that “ATP is the universal energy donor.” 8.Define the terms aerobic and anaerobic. 9.Briefly discuss the function of glycolysis in bioenergetics. What role does NAD play in glycolysis? 10.Discuss the operation of the Krebs cycle and the electron transport chain in the aerobic production of ATP. What is the function of NAD and FAD in these pathways?

70 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Study Questions 11.What is the efficiency of the aerobic degradation of glucose? 12.What is the role of oxygen in aerobic metabolism? 13.What are the rate-limiting enzymes for the following metabolic pathways: ATP-PC system, glycolysis, Krebs cycle, and electron transport chain? 14.Briefly discuss the interaction of anaerobic versus aerobic ATP production during exercise. 15.Discuss the chemiosmotic theory of ATP production.

71 Chapter 3 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Study Questions 16.List and define the six classes of enzymes identified by the International Union of Biochemistry. 17.Briefly discuss the impact of changes in both temperature and pH on enzyme function. 18.Discuss the relationship between lactic acid and lactate.


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