2 Energy: Kinetic energy: Potential energy: Energy is the capacity to cause changeEnergy exists in various forms, some of which can perform workKinetic energy is energy associated with motionHeat (thermal energy) is kinetic energy associated with random movement of atoms or moleculesPotential energy is energy that matter possesses because of its location or structureChemical energy is potential energy available for release in a chemical reactionEnergy can be converted from one form to another
3 Fig. 8-2A diver has more potentialenergy on the platformthan in the water.Diving convertspotential energy tokinetic energy.Figure 8.2 Transformations between potential and kinetic energyClimbing up converts the kineticenergy of muscle movementto potential energy.A diver has less potentialenergy in the waterthan on the platform.
7 Fig. 8-5More free energy (higher G)Less stableGreater work capacityIn a spontaneous changeThe free energy of the systemdecreases (∆G < 0)The system becomes morestableThe released free energy canbe harnessed to do workLess free energy (lower G)More stableLess work capacityFigure 8.5 The relationship of free energy to stability, work capacity, and spontaneous change(a) Gravitational motion(b) Diffusion(c) Chemical reaction
9 Progress of the reaction Fig. 8-6ReactantsAmount ofenergyreleased(∆G < 0)EnergyFree energyProductsProgress of the reaction(a) Exergonic reaction: energy releasedProductsFigure 8.6 Free energy changes (ΔG) in exergonic and endergonic reactionsAmount ofenergyrequired(∆G > 0)EnergyFree energyReactantsProgress of the reaction(b) Endergonic reaction: energy required
10 Figure 8.7 Equilibrium and work in isolated and open systems (a) An isolated hydroelectric system(b) An open hydroelectricsystem∆G < 0Figure 8.7 Equilibrium and work in isolated and open systems∆G < 0∆G < 0∆G < 0(c) A multistep open hydroelectric system
13 H2O P P P Adenosine triphosphate (ATP) P + P P + Energy Fig. 8-9PPPAdenosine triphosphate (ATP)H2OFigure 8.9 The hydrolysis of ATPP+PP+EnergyiInorganic phosphateAdenosine diphosphate (ADP)
14 Membrane protein Solute Solute transported Vesicle Cytoskeletal track Fig. 8-11Membrane proteinPPiSoluteSolute transported(a) Transport work: ATP phosphorylatestransport proteinsADPATP+PiVesicleCytoskeletal trackFigure 8.11 How ATP drives transport and mechanical workATPMotor proteinProtein moved(b) Mechanical work: ATP binds noncovalentlyto motor proteins, then is hydrolyzed
16 + H2O Energy for cellular work (endergonic, energy-consuming Fig. 8-12ATP+H2OEnergy fromcatabolism (exergonic,energy-releasingprocesses)Energy for cellularwork (endergonic,energy-consumingprocesses)Figure 8.12 The ATP cycleADP+Pi