Slides 1 to 74 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Work, Energy and Reactions Chapter 2 Work, Energy and Reactions

Chemical Reactions Metabolism All the chemical reactions in the body Our cells capture, store and use energy to maintain homeostasis and support essential functions. Reactants consumed Products produced Breaks or makes chemical bonds between atoms Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Chemical Reactions Work—movement or change in matter’s physical structure E.g., running, synthesis Energy—ability to do work Kinetic energy Potential energy Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Chemical Reactions Basic Energy Concepts (continued) Potential energy—stored energy E.g., leopard lurks in a tree Kinetic energy—energy of movement E.g., leopard pounces on prey Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Chemical Reactions 3 types of reactions Decomposition—breaks molecule into smaller pieces Synthesis—assembles smaller pieces into larger one Exchange/Replacement—shuffles pieces between molecules Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Chemical Reactions Decomposition Reactions In chemical notation: AB A + B Releases covalent bond energy Hydrolysis—Decomposition reaction with H•OH E.g., food digestion Catabolism—Sum of all the body’s decomposition reactions Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Chemical Reactions Synthesis Reactions In chemical notation: A + B AB Absorbs energy Formation of new bonds Dehydration synthesis Removal of H•OH between molecules Anabolism—Sum of the body’s synthesis reactions Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Chemical Reactions Exchange/Replacement Reaction In chemical notation: AB + CD AC + BD Decomposition and synthesis Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Chemical Reactions Reversible Reactions A + B AB Equilibrium—Condition when the forward and reverse reactions occur at the same rate Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Chemical Reactions Key Note When energy is exchanged, heat is produced. Heat raises local temperatures, but cells cannot capture it or use it to perform work. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Enzymes and Reactions Activation Energy Quantity of energy needed to start a chemical reaction Catalysts reduce activation energy to speed reaction Enzymes catalyze cellular reactions Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Enzymes and Activation Energy Enzymes and Reactions Enzymes and Activation Energy Figure 2-7

Enzymes and Reactions Exergonic—Reactions that release energy E.g., decomposition reactions Endergonic—Reactions that consume energy E.g., synthesis reactions Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings