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CHAPTER 6 - ENERGY FLOW IN CELLS - How do cells control...

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Energy - the capacity to do work Examples - light, heat, electricity Kinetic Energy - energy of movement Examples - chemical energy, positional energy Potential Energy - stored energy Conservation of Energy: total amount of energy in the universe is constant Law of Entropy: useful energy decreases when energy changes forms Laws of Thermodynamics Chemical Reactions: forming and/or breaking chemical bonds Reactants: starting materials Products: made during reaction Energy Flow in Chemical Reactions Exergonic Reactions release energy Endergonic Reactions require energy Coupled Reactions: exergonic reactions provide energy for endergonic reactions (Figure 6-5) How is cellular energy carried between reactions that release energy and those that require energy? ATP Synthesis: energy is stored ATP Breakdown: energy is released Electron carrier molecules transport energy Metabolism: all the chemical reactions in a cell Metabolic Pathway: series of linked reactions
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Unformatted text preview: How do cells control their metabolic reactions? Enzymes regulate chemical reactions Cells couple reactions Energy carriers How is metabolism controlled? Usually proteins A few enzymes are RNA (ribozymes) Enzymes are biological catalysts Catalysts speed up chemical reactions Activation Energy: controls reaction rate Speed up reactions Spefed up reactions that would occur anyway, but slower Not consumed in the reactions Enzymes are very specific Enzyme activity is regulated Five Properties of Biological Catalysts Substrates enter active site Shape change promotes reactions Product released; enzyme ready again Enzyme-Substrate Interactions Regulate synthesis Only active when needed Feedback inhibition Allosteric inhibition Competition inhibition Enzyme Regulation CHAPTER 6 - ENERGY FLOW IN CELLS CHAPTER 6 Page 1...
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