Metabolism and Nutrition Definitions: metabolism, catabolism, anabolism Trophic Strategies Essential versus Nonessential Nutrients Two classes of vitamins.

Metabolism and Nutrition Definitions: metabolism, catabolism, anabolism Trophic Strategies Essential versus Nonessential Nutrients Two classes of vitamins Coupling reactions through common intermediates Different ways the cells utilize the high energy bonds in ATP Coupling endergonic and exergonic reactions Phosphate group transfers Inorganic pyrophosphatase (ATP yields AMP + PPi) High Energy Compounds - Free Energy Currency 1. ATP and phosphoryl group transfer Phosphorylated compounds and regeneration of ATP Substrate level phosphorylation - direct transfer of phosphate catalyzed by kinases Oxidative phosphorylation - indirect ATP generation from proton gradient Thermodynamics versus Kinetics Thermodynamics - Will this reaction happen? G, K eq, E Kinetics - How fast will it happen? Enzymes G is a state function Only depends on the current state, not the path to get there Addtive - can add the G of reactions together The standard free-energy changes for the reactions below are given. Phosphocreatine creatine + Pi DG' = 43.0 kJ/mol ATP ADP + Pi DG' = 30.5 kJ/mol What is the overall DG' for the following reaction? Phosphocreatine + ADP creatine + ATP 1. 73.5 kJ/mol 2. 12.5 kJ/mol kJ/mol kJ/mol 5. DG' cannot be calculated without Keq'. G = G 0 + RTln K G 0 = -RTlnK eq Only use at equilbrium, when G = 0 What is the difference between G and G 0 ? G - can vary within a reaction depending on reaction conditions. At equilibrium, is 0. G 0 - set value of G at standard state Enzymes! 1. Alter the rate of a reaction 2. Lower the transition state for the forward and reverse reactions 3. Only function in a reaction that would occur without it Spontaneous reactions (negative G) 4. Are unchanged Mechanisms to Control of Flux 1. Allosteric control 2. Covalent modifications 3. Substrate Cycles 4. Genetic Control Near equilibrium reactions - G is close to zero -Reactants and products are close to Keq values -Easily reversible -Equilibrium is quickly restored Far equilibrium reactions -Very large negative G. What does this mean about [products]/[reactants]? -Reactants accumulate -You are limited by your enzyme -Changes in [substrate] have little effect on reaction -Changes in the enzyme may affect Thermodynamics and Metabolism Implications of far from equilibrium 1. Metabolic pathways are irreversible 2. Every metabolic pathway has a first committed step - rate limiting step - large negative G 3. Catabolic and anabolic pathways differ. 4. For a multistep pathway as a whole, the overall flux is determined by the rate limiting step 1) Oxidation - Reduction Reactions 2) Group transfer reactions 3) Eliminations, isomerizations, and rearrangements 4) Making or breaking carbon bonds Know these Glucose Transport Nonmediated versus mediated Different types of transport - carriers vs. channels - passive (facilitated) versus active Uniporters, sympoters, antiporters Tissue specific glucose transport - GLUT1, GLUT2, GLUT4 Overview of Glycolysis Stage 1 - prep phase Stage 2 - Energy Recovery Glucose + 2 NAD ADP + 2 Pi 2 pyruvate + 2 NADPH + 2ATP + 2 H 2 O+ 4 H + Summary of Preparatory Phase Energy Harvesting Phase Metabolism of Hexoses other than Glucose Glycogen Metabolism and Gluconeogenesis