Ch08EnergyEnzymesMetabolismPP

Ch08EnergyEnzymesMetabolismPP - 8 Energy, Enzymes, and...

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1 8 Energy, Enzymes, and Metabolism Energy, Enzymes, and Metabolism • What Physical Principles Underlie Biological Energy Transformations? • What Is the Role of ATP in Biochemical Energetics? • What Are Enzymes? • How Do Enzymes Work? • How Are Enzyme Activities Regulated? What Physical Principles Underlie Biological Energy Transformations? The transformation of energy is a hallmark of life. Energy is the capacity to do work, or the capacity for change . Energy transformations are linked to chemical transformations in cells. What Physical Principles Underlie Biological Energy Transformations? All forms of energy can be placed in two categories: Potential energy is stored energy—as chemical bonds, concentration gradient, charge imbalance, etc. Kinetic energy is the energy of movement or motion Energy Conversions and Work What Physical Principles Underlie Biological Energy Transformations? Metabolism : Sum total of all chemical reactions in an organism. Anabolic reactions : Complex molecules are made from simple molecules; energy input is required . Catabolic reactions : Complex molecules are broken down to simpler ones and energy is released .
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2 What Physical Principles Underlie Biological Energy Transformations? The laws of thermodynamics (thermo, “energy”; dynamics, “change”) apply to all matter and all energy transformations in the universe. They help us to understand how cells harvest and transform energy to sustain life. What Physical Principles Underlie Biological Energy Transformations? First law of thermodynamics : Energy is neither created nor destroyed. When energy is converted from one form to another, the total energy before and after the conversion is the same. What Physical Principles Underlie Biological Energy Transformations? Second law of thermodynamics : When energy is converted from one form to another, some of that energy becomes unavailable to do work as lost as heat. No energy transformation is 100 percent efficient. The Laws of Thermodynamics What Physical Principles Underlie Biological Energy Transformations? Entropy is a measure of the disorder in a system. It takes energy to impose order on a system. Unless energy is applied to a system, it will be randomly arranged or disordered. What Physical Principles Underlie Biological Energy Transformations? In any system: Total energy = usable energy + unusable energy enthalpy ( H ) = free energy ( G ) + entropy ( S ) or H = G + TS (T = absolute temperature) G = H – TS
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3 What Physical Principles Underlie Biological Energy Transformations? Change in energy can be measured in calories or joules. Change in free energy ( Δ G) in a reaction is the difference in free energy of the products and the reactants. What Physical Principles Underlie Biological Energy
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This document was uploaded on 12/01/2010.

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Ch08EnergyEnzymesMetabolismPP - 8 Energy, Enzymes, and...

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