co06 - CHAPTER 6 METABOLISM ENERGY AND ENZYMES Chapter...

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CHAPTER 6 M ETABOLISM : E NERGY AND E NZYMES Chapter Outline 6.1 Cells and the Flow of Energy A. Energy 1. Energy is capacity to do work; cells continually use energy to develop, grow, reproduce, etc. 2. Kinetic energy is energy of motion; all moving objects have kinetic energy. 3. Potential energy is stored energy. a. A rolling ball and a contracting muscle are forms of mechanical energy . b. Food is chemical energy that contains potential energy. c. When a moose lifts its leg, it converts chemical energy into mechanical energy. B. Two Laws of Thermodynamics 1. First law of thermodynamics (also called the law of conservation of energy) a. Energy cannot be created or destroyed; it can be changed from one form to another. b. In an ecosystem, sunlight energy is converted in photosynthesis to chemical energy of plant tissue; some of the chemical energy in the plant is converted to chemical energy in an animal which ultimately can become mechanical energy or heat loss. c. Photosynthesis uses solar energy to convert the energy-poor carbon dioxide and water into energy- rich carbohydrates. d. The plant or animal never create the energy; it flows through the system and dissipates as heat 2. Second law of thermodynamics a. Energy cannot be changed from one form into another without a loss of usable energy. b. Heat is form of energy but quickly dissipates into the environment; because heat dissipates, it can never be converted back to the other forms of energy. C. Cells and Entropy 1. Every energy transformation makes the universe less organized and more disordered; entropy is a measure of this disorganization. 2. When ions distribute themselves randomly across a membrane, entropy has increased. 3. Organized/usable forms of energy as in the glucose molecule, have low entropy; unorganized/less stable forms have high entropy. 4. Energy conversions result in heat and therefore the entropy of the universe is always increasing. 5. It takes a constant input of usable energy from the sun from to produce the food you eat to keep you organized. 6.2 Metabolic Reactions and Energy Transformations A. Metabolism 1. Metabolism is the sum of all the biochemical reactions in a cell. 2. In a reaction A + B C + D, A and B are reactants and C and D are products . 3. Free energy ( G ) is the amount of energy that is free to do work after a chemical reaction. 4. Change in free energy is noted as G ; a negative G means that products have less free energy than reactants; the reaction occurs spontaneously. 5.
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co06 - CHAPTER 6 METABOLISM ENERGY AND ENZYMES Chapter...

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