Figure 8.2 A diver has more potential Diving converts energy on the platform potential energy to than in the water. kinetic energy. Climbing up converts the kinetic A diver has less potential energy of muscle movement energy in the water to potential energy. than on the platform.
Figure 8.5 • More free energy (higher G) • Less stable • Greater work capacity In a spontaneous change • The free energy of the system decreases (∆G < 0) • The system becomes more stable • The released free energy can be harnessed to do work • Less free energy (lower G) • More stable • Less work capacity (a) Gravitational motion (b) Diffusion (c) Chemical reaction
Figure 8.6 (a) Exergonic reaction: energy released, spontaneous Reactants Amount of energy released Free energy (∆G < 0) Energy Products Progress of the reaction (b) Endergonic reaction: energy required, nonspontaneous Products Amount of energy required Free energy (∆G > 0) Energy Reactants Progress of the reaction
Figure 8.10 Transport protein Solute ATP ADP Pi P Pi Solute transported (a) Transport work: ATP phosphorylates transport proteins. Vesicle Cytoskeletal track ATP ADP Pi ATP Motor protein Protein and vesicle moved (b) Mechanical work: ATP binds noncovalently to motor proteins and then is hydrolyzed.
Figure 8.13 Course of reaction EA without without enzyme EA with enzyme enzyme is lower Free energy Reactants Course of ∆G is unaffected reaction by enzyme with enzyme Products Progress of the reaction
Figure 8.15-3 1 Substrates enter active site. 2 Substrates are held in active site by weak interactions. Substrates Enzyme-substrate complex 3 Active site can lower EA and speed up a reaction. 6 Active site is available for two new substrate molecules. Enzyme 5 Products are 4 Substrates are released. converted to products. Products
Figure 8.16 Optimal temperature for Optimal temperature for typical human enzyme (37°C) enzyme of thermophilic (heat-tolerant) Rate of reaction bacteria (77°C) 0 60 20 80 40 100 120 Temperature (°C) (a) Optimal temperature for two enzymes Optimal pH for pepsin Optimal pH for trypsin (stomach (intestinal enzyme) enzyme) Rate of reaction 0 1 5 2 3 4 6 7 8 9 10 pH (b) Optimal pH for two enzymes
Figure 8.19 (a) Allosteric activators and inhibitors (b) Cooperativity: another type of allosteric activation Allosteric enzyme Active site Substrate with four subunits (one of four) Regulatory site (one Activator Stabilized active of four) Inactive form Active form Stabilized active form form Oscillation Non- Inhibitor Inactive form Stabilized inactive functional active site form
Figure 8.21 Initial substrate Active site (threonine) available Threonine in active site Enzyme 1 (threonine Isoleucine deaminase) used up by cell Intermediate A Active site of Feedback enzyme 1 is inhibition Enzyme 2 no longer able to catalyze the Intermediate B conversion of threonine to Enzyme 3 intermediate A; pathway is Intermediate C switched off. Isoleucine binds to Enzyme 4 allosteric site. Intermediate D Enzyme 5 End product (isoleucine)