BIO 101 1st Edition Lecture 11 Outline of Last Lecture I Cytoskeleton a Microtubules b Microfilaments c Intermediate filaments II The Cell Surface a Cell Walls b Gylcocalyx c Intercellular Junctions Outline of Current Lecture I Metabolism a Metabolic Pathways II Classified Energetics a Catabolic pathways b Anabolic pathways III Energy a Kinetic b Potential IV Thermodynamics V Chemical reactions a Exergonic b Endergonic Chapter 8 Introduction to Metabolism Metabolism all of an organism s chemical processes There are thousands of chemical reactions in the cell They are coordinated and integrated with one another Organized into metabolic pathways Metabolic pathways an ordered series of chemical reactions in which the PRODUCT of one reaction becomes the REACTANT for the next reaction a stepwise process an example of a pathway Two Basic Types of Pathways Classified Energetics BIO 101 1st Edition 1 Catabolic pathways pathways that release energy by breaking down complex molecules into simpler molecules Complex Simple release energy 2 Anabolic pathways pathways that consume energy to build complex molecules starting with simple molecules Simple Complex consumes energy Energy exists in two different forms 1 Kinetic energy energy of motion 2 Potential energy energy of position Energy can be changed from one form to another form Ex chemical potential energy in gasoline can be transformed into kinetic energy to move pistons in a car Thermodynamics study of energy transformations 1st Law of Thermodynamics energy can be transferred or transformed but can NOT be created or destroyed 2nd Law of Thermodynamics every energy transfer makes the universe more disordered Energy with Regard to Chemical Reactions Enthalpy H total potential energy of a molecule BOND Energy Each chemical reaction proceeds with a change in enthalpy In chemical reaction reactant is changed into the product Reactant H Product H If there is more bond energy in the product than is in the reactant then energy has to be put in to make the reaction go If there is less bond energy in the product than in the reactant then energy is released by the reaction Entropy S quantitative measure of disorder System may become more ordered but only at the expense of the surroundings BIO 101 1st Edition As with H bond energy each chemical reaction proceeds with some change in entropy Both the H and the S factors must be considered in the energy of chemical reactions Energy with Regard to Chemical Reactions In a chemical reaction reactant molecules are changed into product molecules Reactants products Each chemical reaction proceeds with a change in FREE ENERGY G amount of energy available to do work FREE ENERGY includes both enthalpy and entropy factors as shown in this equation The of a chemical reaction is important because it determines if the reaction will be spontaneous or not There are two kinds of chemical reactions with regard to 1 Exergonic reactions 2 Endergonic reactions Exergonic Reactions Spontaneous Reactants have MORE bond energy H than products energy is released S tends to increase during the reaction products are more disordered G is maximum amount of work that reaction can do VS Endergonic Reactions Not spontaneous Reactants have LESS bond energy H than products energy is consumed S tends to decrease during the reaction products are more ordered G is minimum amount of work required to make a reaction go
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