Chapter 6 Ground Rules of Metabolism

Chapter 6 Ground Rules of Metabolism - Chapter 6 Ground...

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Chapter 6 Ground Rules of Metabolism I. The Old Man of the Woods A. All living things have a need for energy. B. Metabolism is the controlled capacity to acquire and use energy for the synthesis and breakdown of organic compounds. II. Energy and Life A. Energy is the capacity to make things happen, to cause change, to do work. B. Two laws govern energy transformations: 1. First law of thermodynamics states that the total amount of energy in the universe is constant; it cannot be created nor destroyed; it can only change form. a. Energy cannot be produced by a cell; it can only be borrowed from someplace else. b. Energy can be of high quality, that is, highly concentrated and usable; or it can be of low quality, such as heat that is released into the universe. 2. Second law of thermodynamics states that the spontaneous direction of energy flow is from high- to low-quality forms. a. Each conversion results in production of energy (usually heat) that is unavailable for work. b. As systems lose energy they become more disorganized; the measure of this disorder is called entropy. C. The world of life (plant and animal) maintains a high degree of organization only because it is being resupplied with energy from the sun. III. The Nature of Metabolism A. Energy Changes in Metabolic Reactions 1. Concepts concerning reactions: a. Products (end of reaction) may have more or less energy than the reactants (beginning of reaction). b. Most reactions are reversible. c. Reversible reactions approach equilibrium. 2. Bond Energies a. Bond energy is measured in kilocalories per mole. b. Bond energies for covalent bonds are much higher (about 90) than those of ionic and hydrogen bonds (about 5). 3. Energy Losses and Gains
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Chapter 6 Ground Rules of Metabolism - Chapter 6 Ground...

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