tailieunhanh - Lecture Biochemistry (2/e): Chapter 3 - Reginald Garrett, Charles Grisham

Chapter 3 introduce the Thermodynamics of biological systems. The following will be discussed in this chapter: Basic thermodynamic concepts, physical significance of thermodynamic properties, pH and the standard state, the effect of concentration, coupled processes, high-energy biomolecules. | Chapter 3 Thermodynamics of Biological Systems to accompany Biochemistry, 2/e by Reginald Garrett and Charles Grisham All rights reserved. Requests for permission to make copies of any part of the work should be mailed to: Permissions Department, Harcourt Brace & Company, 6277 Sea Harbor Drive, Orlando, Florida 32887-6777 Outline Basic Thermodynamic Concepts Physical Significance of Thermodynamic Properties pH and the Standard State The Effect of Concentration Coupled Processes High-Energy Biomolecules Basic Concepts The system: the portion of the universe with which we are concerned The surroundings: everything else Isolated system cannot exchange matter or energy Closed system can exchange energy Open system can exchange either or both The First Law The total energy of an isolated system is conserved. E (or U) is the internal energy - a function that keeps track of heat transfer and work expenditure in the system E is heat exchanged at constant volume E is independent of path E2 - E1 = E = q + w q is heat absorbed BY the system w is work done ON the system Enthalpy A better function for constant pressure H = E + PV If P is constant, H = q H is the heat absorbed at constant P Volume is approx. constant for biochemical reactions (in solution) So H is approx. same as E The Second Law Systems tend to proceed from ordered to disordered states The entropy change for (system + surroundings) is unchanged in reversible processes and positive for irreversible processes All processes proceed toward equilibrium - ., minimum potential energy Entropy A measure of disorder An ordered state is low entropy A disordered state is high entropy dSreversible = dq/T The Third Law The entropy of any crystalline, perfectly ordered substance must approach zero as the temperature approaches 0 K At T = 0 K, entropy is exactly zero For a constant pressure process: Cp = dH/dT Free Energy Hypothetical quantity - allows chemists to asses whether reactions will occur G = H - TS For any . | Chapter 3 Thermodynamics of Biological Systems to accompany Biochemistry, 2/e by Reginald Garrett and Charles Grisham All rights reserved. Requests for permission to make copies of any part of the work should be mailed to: Permissions Department, Harcourt Brace & Company, 6277 Sea Harbor Drive, Orlando, Florida 32887-6777 Outline Basic Thermodynamic Concepts Physical Significance of Thermodynamic Properties pH and the Standard State The Effect of Concentration Coupled Processes High-Energy Biomolecules Basic Concepts The system: the portion of the universe with which we are concerned The surroundings: everything else Isolated system cannot exchange matter or energy Closed system can exchange energy Open system can exchange either or both The First Law The total energy of an isolated system is conserved. E (or U) is the internal energy - a function that keeps track of heat transfer and work expenditure in the system E is heat exchanged at constant volume E is independent of path E2 - .