MCB 450 1st Edition Exam 3 Study Guide Lectures 14 19 Lecture 14 March 10 I Be able to define metabolism a The complex of physical and chemical processes occurring within a living cell or organism that are necessary for the maintenance of life II Identify the factors that make ATP an energy rich molecule a 2 phosphoric anhydride linkages i High transfer potential b Has 4 negative charges c Hydrolysis of phosphoric anhydride linkages is thermodynamically favorable III Explain how ATP can power reactions that would otherwise not take place a First reaction of glycolysis b ATP hydrolysis drives metabolism by shifting the equilibrium K eq of coupled reactions by a factor of 108 in cells IV Describe the relation between the oxidation state of a carbon molecule and its usefulness as a fuel a The more reduced a carbon molecule is the more energy and usefulness it has as a fuel V Know the names general structures and functions of the main anabolic and catabolic carriers a Catabolic carriers i ADP ATP ii NAD NADH 1 NAD collects electrons released in catabolism iii FAD FADH2 1 carries two hydrogen ions iv FMN FMNH2 1 an electron carrier component of the ETC b Anabolic carriers i ADP ATP ii NADP NADPH 1 2 NADPHs supply 2 hydrides 2 H 4 e Lecture 15 March 17 I II Be able to list the intermediates of the glycolytic pathway and the types of reactions catalyzing each step a Glucose Glucose 6 phosphate i catalyzed by hexokinase b Glucose 6 phophate Fructose 6 phosphate i catalyzed by phosphoglucose isomerase c Fructose 6 phosphate Fructose 1 6 bisphosphate i Catalyzed by phosphofructokinase d Fructose 1 6 bisphosphate Glyceraldehyde 3 phosphate i Catalyzed by aldolase e Glyceraldehyde 3 phospate Dihydroxyacetone phosphate or 1 3Bisphosphoglycerate i Catalyzed by triose phosphate isomerase or glyceraldehyde 3phosphate dehydrogenase f 1 3 Bisphosphoglycerate 3 Phosphoglycerate i Catalyzed by phosphoglycerate kinase g 3 Phosphoglycerate 2 Phosphoglycerate i Catalyzed by phosphoglycerate mutase h 2 Phosphoglycerate Phosphoenolpyruvate i Catalyzed by enolase i Phosphoenolpyruvate pyruvate i Catalyzed by pyruvate kinase Know the regulatory steps of glycolysis and understand some physiologically differences between its regulation in liver and muscles a Phosphofructokinase hexokinase and pyruvate kinase play important roles in regulating glycolysis b Regulatory steps Glucose Glucose 6 phosphate Fructose 6 phosphate Fructose 1 6 Bisphosphate and Phosphoenolpyruvate Pyruvate c In muscles i High levels of ATP inhibits phosphofructokinase ii High levels of AMP will activate phosphofructokinase iii High levels of glucose 6 phosphate inhibit hexokinase iv The inhibition of phosphofructokinase leads to the inhibition of hexokinase III IV v High levels of ATP and alanine inhibit pyruvate kinase d In the liver i Phosphofructokinase is inhibited by citrate ii Glucokinase instead of hexokinase in liver phosphorylates glucose only when glucose is abundant Be able to describe the effects of allosteric and covalent regulation on glycolysis Understand how the fate of pyruvate is dictated by the cells need a 3 fates of pyruvate conversion into i Ethanol ii Lactate iii Carbon dioxide and water Lecture 16 March 19 I II III IV Know the main entry points of noncarbohydrates precursors into gluconeogenesis a Lactate and some amino acids enter at conversion of pyruvate to oxaloacetate b Some amino acids enter at the conversion of oxaloacetate into phosphoenolpyruvate c Glycerol enters at the conversion of diydroxyacetone phosphate into glyceraldehyde 3 phosphate Differentiate and contrast the coordinated regulation of glycolysis and gluconeogenesis Be able to identify the two stages of the pentose phosphate pathway and explain how the pathways is coordinated with glycolysis and gluconeogenesis a Phase 1 Oxidative b Phase 2 Nonoxidative Know the enzymes that controls the pentose phosphate pathway a Glucose 6 phosphate dehydrogenase b Lactonase c 6 phosphogluconate dehydrogenase d Phosphopentose isomerase e Phosphopentose epimerase f Transketolase g Transaldolase Lecture 17 March 31 I Be able to list the coenzymes of the pyruvate dehydrogenase and the steps involved in the conversion of pyruvate to acetyl CoA a Coenyzmes i Thiamine pyrophosphate TPP ii Lipoic acid iii Flavin adenine dinucleotide FAD II III iv CoA v Nicotinamide adenine dinucleotide NAD b Steps i Decarboxylation 1 Pyruvate combines with the ionized carbanion form of TPP and is then decarboxylated to create hydroxyethyl TPP 2 Catalyzed by pyruvate dehydrogenase component E1 ii Oxidation 1 The hydroxyethyl group attached to TPP is oxidized to form an acetyl group while simultaneously being transferred to lipoamide derivative of lipoic acid a This transfer results in the formation of an energy rich thioester bond 2 The disulfide group of lipoamide is reduced to its disulfhydryl form and yields acetyllipoamide 3 Catalyzed by pyruvate dehydrogenase component E1 iii Transfer of the resultant acetyl group to CoA 1 The acetyl group is transferred from acetyllipoamide to CoA to form acetyl CoA 2 Catalyzed by dihydrolipoyl transacetylase E2 3 The energy rich thioester bond is preserved as the acetyl group is transferred Be able to recognize the intermediates and products of the citric acid cycle a Intermediates i Citryl CoA ii Cis Aconitate iii Oxalosuccinate b Products i Citrate ii Isocitrate iii Alpha ketoglutarate iv Succinyl CoA v Succinate vi Fumarate vii Malate viii Oxaloacetate Understand how the pyruvate dehydrogenase complex and the citric acid cycle are regulated a Pyruvate dehydrogenase complex i Regulated by phosphorylation 1 Phosphorylation of the pyruvate dehydrogenase component E1 by a pyruvate dehydrogenase PDH kinase switches off the activity of the complex a PDH kinase will be activated when high levels of Acetyl CoA NADH and ATP are detected 2 The activation of a PDH phosphatase will switch the activity of the complex back on a PDH phosphatase will be activated when high levels of ADP and Pyruvate are detected b Citric Acid Cycle i Primarily regulated by isocitrate dehydrogenase and alpha ketoglutarate enzymes Know the roles of acetyl CoA and oxaloacetate Explain the differences between the citric acid cycle and the glyoxylate cycle a Citric Acid Cycle i Acetyl CoA has only one fate oxidation to CO2 and H2O ii One molecule of acetyl CoA will enter per turn of the cycle b Glyoxylate Cycle i Allows the conversion of acetyl CoA into glucose ii Bypasses