lecture2_9_4_08 - Lecture 2 Chapter 1: Stryer water...

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Lecture 2 • water • thermodynamics Chapter 1: Stryer ! G = H - T S Thermodynamics All molecular processes within cells are governed by thermodynamics and kinetics. Living things require a continuous throughput of energy. Thermodynamics describe the relationships among various forms of energy and how energy affects matter on a macroscopic level. energy distribution at equilibrium; how energetically stable is the system and each of its components With a knowledge of thermodynamics, we can determine whether a physical process is possible. Living organisms are open systems - can exchange matter and energy with surroundings. Thermodynamics The primary usefulness of thermodynamics to biochemists lies in predicting whether particular chemical reactions could occur spontaneously. Described by Gibb’s free energy ( ! G) - defined in terms of enthalpy ( ! H) and entropy ( ! S) What compounds could possible serve as energy sources for an organism? Common reaction - oxidation of an organic molecule by molecular oxygen releases energy. Organisms can obtain energy by oxidizing carbohydrates, fats, and/or proteins. First Law of Thermodynamics Energy can be neither created nor destroyed. E = E final E initial = q w E is energy; q is heat absorbed by system; w is work done by system on surroundings. Heat is a reflection of random motion; work is defined as force times distance moved, therefore associated with organized motion. q exothermic; system releases heat + q endothermic; system gains heat SI unit is joule (J), but calorie (cal) is often used. 1 cal = 4.184 J
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State Functions State functions are independent of the path a system follows. The energy of a system depends only on its current properties or
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lecture2_9_4_08 - Lecture 2 Chapter 1: Stryer water...

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