Energy

Outline Laws of Thermodynamics Chemical Reactions Enzymes How cells “make” and use Energy: ATP Cell Respiration Photosynthesis

Why do living organisms need energy? First Law of Thermodynamics –Energy cannot be created or destroyed. –Energy can be converted. Second Law of Thermodynamics –Energy transformations proceed spontaneously –Some energy is lost as heat. –Entropy increases More ordered  Less ordered

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Kinetic Potential Kinetic to Potential Figure 5.1A&B Kinetic & Potential Energy

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Heat Chemical reactions ATP Glucose + Oxygen Water Carbon dioxide + Energy for cellular work Substrates or Reactants Products Chemical reactions Figure 5.2B Energy transformations in a cell

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Potential energy Reactants Energy required Products Amount of energy required Figure 5.3A Endergonic reactions require energy

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Reactants Energy released Products Amount of energy released Potential energy Figure 5.3B Exergonic reactions release energy

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Reactants Products Activation Energy Barrier Figure 5.5A Enzymes lower activation energy Enzyme Catalyst

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Activation energy – extra energy required – destabilizes existing chemical bonds – initiates a chemical reaction Enyzme – Catalyst – lowers activation energy Activation Energy

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Figure 5.6 The catalytic cycle of an enzyme Enzyme with Active site Substrate binds to enzyme Enzyme Glucose Fructose Products released Substrate converted to products Active site Substrate (sucrose) H2OH2O

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings ATP ADP + P Energy for endergonic reactions Energy from exergonic reactions Phosphorylation Hydrolysis Figure 5.4C The ATP cycle

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Phosphate groups ATP Energy PPPPPP Hydrolysis Adenine Ribose H2OH2O Adenosine diphosphate Adenosine Triphosphate + + ADP Fig 5.4A ATP Structure and Hydrolysis

Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings ATP Chemical work Mechanical work Transport work P P P P P P P Molecule formedProtein moved Solute transported ADP + Product Reactants Motor protein Membrane protein Solute + Figure 5.4B ATP Powers Cellular Work

ATP Synthesis 1. ADP + Phosphate  ATP 2. Mechanisms of ATP synthesis  Chemiosmosis  Substrate Level Phosphorylation

Fig. 9.3 (TEArt) H+H+ ATP ADP + P ATP Synthase H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. ATP synthesis: Chemiosmosis

P PEP Enzyme ADP Adenosine P P P ATP P P Adenosine Pyruvate Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Substrate ATP Synthesis Substrate-Level Phosphorylation

END Part I: Energy