It is exam based on chapter 6, 7, 15, 16 & 17 of textbook I sent you. The exam is around 15 multiple choices or Y/N questions. You only have 20 minutes to answer them and then question will close after that
1-1kpef0oe.pdf Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 6 Energy Transfer in the Body Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Adenosine Triphosphate (ATP) • Food macronutrients provide major sources of potential energy but do not transfer directly to biologic work Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Adenosine Triphosphate (ATP) • Cells’ two major energy-transforming activities: ▪ Extract potential energy from food and conserve it within the ATP bonds ▪ Extract and transfer the chemical energy in ATP to power biologic work Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins • ATP forms from adenosine linked to three phosphates • Adenosine diphosphate (ADP) forms when ATP joins with water, catalyzed by the enzyme adenosine triphosphatase (ATPase) Adenosine Triphosphate (ATP), cont. ATP + H2O ADP + P - ∆G7.3 kcal/mol ATPase Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins ATP Production • Free energy liberated in ATP hydrolysis powers all forms of biologic work • ATP represents the cell’s “energy currency” Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins ATP: A Limited Currency • Cells contain only a small quantity of ATP so it must continually be resynthesized • ATP levels decrease in skeletal muscle only under extreme exercise conditions • The body stores 80 to 100 g of ATP at any time under normal resting conditions, enough stored energy to power 2 to 3 seconds of maximal exercise Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Phosphocreatine (PCr): The Energy Reservoir • Some energy for ATP resynthesis comes from anaerobic splitting of a phosphate from PCr • Cells store approximately 4 to 6 times more PCr than ATP • PCr reaches its maximum energy yield in about 10 s Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Biologic Work in Humans • Three forms of biologic work 1. Chemical: Biosynthesis of cellular molecules 2. Mechanical: Muscle contraction 3. Transport: Transfer of substances among cells Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Factors That Affect Rate of Bioenergetics • Enzymes ▪ Protein catalysts: accelerate chemical reactions without being consumed or changed in the reaction • Coenzymes ▪ Nonprotein organic substances: facilitate enzyme action by binding a substrate to its specific enzyme Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Classifications of Enzymes • Oxidoreductases (example: lactate dehydrogenase) • Transferases (example: hexokinase) • Hydrolases (example: lipase) • Lyases (example: carbonic anhydrase) • Isomerases (example: phosphoglycerate mutase) • Ligases (example: pyruvate carboxylase) Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Turnover Number • Enzymes do not all operate at the same rate ▪ Turnover number - number of moles of substrate that react to form a product per mole of enzyme per unit time - pH and temperature alter enzyme activity Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Lock and Key Mechanism • Enzyme-substrate interaction ▪ Enzyme turns on when its active site joins in a “perfect fit” with the substrate’s active site ▪ Ensures that the correct enzyme matches with its specific substrate to perform a particular function Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Energy Release from Macronutrients • Three stages lead to release and energy conservation by cells for biologic work: ▪ Stage 1: Digestion, absorption, and assimilation of relatively large food macromolecules into smaller subunits ▪ Stage 2: Degrades amino acids, glucose, and fatty acid and glycerol units into acetyl coenzyme A ▪ Stage 3: Acetyl-coenzyme A degrades to CO2 and H2O with considerable ATP production Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Six Macronutrient Fuel Sources 1. Triacylglycerol and glycogen molecules stored within muscle cells 2. Blood glucose 3. Free fatty acids 4. Intramuscular- and liver-derived carbon skeletons of amino acids 5. Anaerobic reactions in the initial phase of glucose breakdown 6. PCr phosphorylates ADP under enzyme control (creatine kinase and adenylate kinase) Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Energy Release from Carbohydrate • Carbohydrate’s primary function supplies energy for cellular work • The complete breakdown of one mole of glucose yields 686 kcal of available energy ▪ Bonds within ATP conserve about 263 kcal; the remaining dissipates as heat • The complete oxidation of one glucose molecule in skeletal muscle yields 36 ATPs C6H12O6 + 6O2 6CO2 + 6H2O – ∆G 686 kcal/mol Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Anaerobic Versus Aerobic Glycolysis • Two forms of carbohydrate breakdown: 1. Anaerobic (rapid) glycolysis results in pyruvate-to-lactate formation with the release of about 5% of energy within the original glucose molecule 2. Aerobic (slow) glycolysis results in pyruvate-to-acetyl-CoA-to-citric acid cycle and electron transport of the remaining energy within the original glucose molecule Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Anaerobic Glycolysis: Rapid Glycolysis • Anaerobic (rapid) glycolysis regulated by: ▪ Glycolytic enzymes hexokinase, pyruvate kinase, and phosphofructokinase ▪ Fructose 1,6-disphosphate levels ▪ Rapid glycolysis forms lactate with 4 total ATP produced (2 net ATP – 14.6 kcal/mol) ▪ Rapid glycolysis generate about 5% of the total ATP during complete glucose breakdown ▪ Rapid glycolysis occurs without molecular oxygen involvement Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Glucose-to-Glycogen and Glycogen-to-Glucose Conversion • Glycogenesis (glycogen synthesis) ▪ Surplus glucose forms glycogen in low cellular activity and/or with depleted glycogen reserves • Glycogenolysis (glycogen breakdown) ▪ Glycogen reserves break down to produce glucose in high cellular activity with glucose depletion Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Regulation of Glycolysis • Three factors regulate glycolysis: 1. Four key glycolytic enzymes: hexokinase, phosphorylase, phosphofructokinase, pyruvate kinase 2. Levels of fructose 1,6-disphosphate 3. Oxygen in abundance inhibits glycolysis Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Lactic Acid Versus Lactate • Lactic acid forms during anaerobic glycolysis. In the body, it dissociates to release a hydrogen ion (H+). The remaining compound binds with a positively charged sodium (Na+) ion or potassium (K+) ion to form the acid salt lactate Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Slow (Aerobic) Glycolysis: The Citric Acid Cycle • Rapid glycolysis releases only about 5% of the total energy within glucose; the remaining energy releases when pyruvate converts to acetyl-CoA and enters the citric acid cycle (also called the Krebs cycle) • The citric acid cycle represents the second stage of carbohydrate breakdown to produce CO2 and hydrogen atoms within mitochondria Pyruvate + NAD+ CoA Acetyl-CoA + CO2 + NADH + + H+ Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Slow (Aerobic) Glycolysis Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Citric Acid Cycle (11 Steps) Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Total Energy Transfer from Glucose Catabolism • The complete breakdown of glucose yields 34 ATPs ▪ Because two ATPs initially phosphorylate glucose, 32 ATP molecules equal the net ATP yield from glucose catabolism in skeletal muscle ▪ Four ATP molecules form directly from substrate-level phosphorylation (glycolysis and citric acid cycle) ▪ 28 ATP molecules regenerate during oxidative phosphorylation Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Net ATP from Glucose Catabolism Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Energy Release from Fat • Three specific energy sources for fat catabolism: 1. Triacylglycerols stored directly in muscle mitochondria 2. Circulating triacylglycerols in lipoprotein complexes 3. Circulating free fatty acids mobilized from triacylglycerols in adipose tissue Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Fat Catabolism • Complete oxidation of a triacylglycerol molecule yields about 460 ATP molecules • Stored fat serves as the most plentiful source of potential energy • Fat becomes the primary energy fuel for exercise and recovery when intense, long- duration exercise depletes both blood glucose and muscle glycogen Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Oxidation and Reduction • Oxidation (always involves electron loss) ▪ Reactions that transfer oxygen, hydrogen atoms, or electrons ▪ A loss of electrons always occurs with a net gain in valence • Reduction (always involves electron gain) ▪ Any process in which atoms in an element gain electrons, with a corresponding net decrease in valence Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Fat Catabolism, cont. • Fat supplies 30 to 80% of energy for biologic work depending on nutritional status, level of training, and intensity and duration of physical activity • Total fuel reserves from fat in a young adult male: ▪ 60,000 to 100,000 kcal stored in adipocytes ▪ 3000 kcal stored in intramuscular triacylglycerol Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Dynamics of Fat Mobilization • Hormone-sensitive lipase stimulates triacylglycerol (TAG) breakdown into its glycerol and fatty acid components. • The blood transports free fatty acids (FFAs) released from adipocytes and bound to plasma albumin. • Energy releases when TAG stored within muscle fibers degrades to glycerol and fatty acids. Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Glycerol and Fatty Acid Catabolism • Glycerol ▪ Substrate phosphorylation degrades pyruvate to form ATP ▪ Hydrogen atoms pass to NAD+, and the citric acid cycle oxidizes pyruvate. ▪ Complete breakdown of a single glycerol molecule synthesizes 19 ATP molecules • Fatty Acids ▪ Transform into acetyl-CoA in mitochondria via β-oxidation for entry into the citric acid cycle Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Glycerol and Fatty Acid Catabolism, cont. Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Electron Transport • Electron transport represents the final common pathway where electrons extracted from hydrogen pass to oxygen • Mitochondrial oxygen levels drive the respiratory chain by serving as the final electron acceptor to combine with hydrogen to form water Oxidizing hydrogen and electron transport Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Oxygen’s Role in Energy Metabolism • Serves as the major oxidizing agent in tissues • Ensures that energy transfer reactions proceed at appropriate rate Aerobic metabolism refers to energy-generating catabolic reactions, where oxygen serves as the final