Chapter 8 Energy Enzymes

Chapter 8 Energy Enzymes - Energy Energy is the capacity to...

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Energy Energy is the capacity to do work, or the capacity to change . 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.
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Conservation of energy The dam holds water with potential energy, which it releases in a controlled fashion as kinetic energy , the energy of movement, which can do work, like running a turbine to produce kinetic energy in the form of a flow of electrons. In biological systems, potential energy is stored in chemical bonds and concentration gradients . This energy is used for cellular activities like macromolecular synthesis, motion, and active transport of ions.
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The First and Second laws of thermodynamics
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In words 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. Second Law of Thermodynamics : When energy is converted from one form to another, some of that energy becomes unavailable to do work. No energy transformation is 100 percent efficient.
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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. Think of your bedroom! The Second Law states that during energy transformations, the amount of usable energy, also known as free energy ( G ), must go down. The unusable energy is lost as disorder -- entropy (S ) -- primarily as heat . Entropy
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The Second Law states that during energy transformations, the amount of usable energy, also known as free energy ( G ), must go down. The unusable energy is lost as disorder -- entropy (S ) -- primarily as heat. 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 ΔG = ΔH – TΔS If ΔG is positive, free energy is consumed. If ΔG is negative, free energy is released. Note that an increase in entropy (ΔS) will contribute to a negative ΔG. In equations
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Changes in entropy In a condensation (or dehydration ) reaction to produce a protein, many amino acids produce one polypeptide, so disorder (entropy S) falls. Since G = H – T S, G is positive ; ignoring H, energy is likely to be required for the ANABOLIC reaction. In a hydrolysis reaction, one polypeptide is broken down into many amino acids, so disorder (entropy S) increases, G is negative ; energy is likely to be released in this CATABOLIC reaction.
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Each energy transformation is accompanied by an increase in disorder. Therefore, living organisms must have a constant supply of
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This note was uploaded on 04/19/2011 for the course LS 2 taught by Professor Pires during the Spring '08 term at UCLA.

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Chapter 8 Energy Enzymes - Energy Energy is the capacity to...

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