EXAM 2 - EXAM2 Chapter6 EnergyFlowinCells WhatisEnergy?...

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EXAM 2 17:46 Chapter 6 Energy Flow in Cells What is Energy? Energy Energy = the capacity to do work Kinetic Energy = energy of movement Light Heat Electricity Potential Energy = stored energy Chemical energy Positional energy Laws of Thermodynamics Conservation of energy Amount of energy in a closed system remains constant When converted from one form to another, useful energy decreases
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How efficient is your car (on average) at converting the energy in gas to kinetic energy? 25% Potential Energy to Kinetic Energy 100 units chemical energy (concentrated)—75 units heat energy+25 units kinetic energy  (motion) Why is it possible for living organisms to comply with the 2 nd  law of thermodynamics? There is a constant input of energy from the sun How Does Energy Flow in Chemical Reactions? Chemical reaction: forming and/or breaking chemical bonds among atoms Reactants: starting materials Products: result of the reaction Exergonic Reactions Pg. 101 When a reaction takes place, energy is released into the environment Figure 6-2a Endergonic Reactions
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Pg. 101 Start off with low energy reactants; we put in a lot of energy to get reaction; we  get a better reaction out. Ex. Photosynthesis Figure 6-2b Coupled Reactions Exergonic reactions provide the energy needed for endergonic reactions Figure 6-3 Which reaction is NOT an exergonic reaction? Protein synthesis What must be overcome in order for reactants to start reacting? Activation energy How is Cellular Energy Carried Between Coupled Reactions? Figure 6-4 ATP Synthesis: Energy is Stored
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Pg. 104 Coupled Reactions Within Living Cells Figure 6-5 Electron Carriers Figure 6-6 How Do Cells Control Their Metabolic Reactions? Metabolism = sum of all the chemical reactions in a cell Exergonic + Endergonic = Metabolism Metabolic Pathway: series of reactions linked in a sequence Metabolic Pathways Figure 6-7 How is Metabolism Controlled? Enzymes regulate chemical reactions Cells couple reactions Energy carriers capture energy from exergonic reactions and deliver to  endergonic reactions
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Catalysts Catalysts speed up chemical reactions Enzymes are biological catalysts Usually proteins A few enzymes are RNA (ribozymes) Activation Energy: Controls Rate of Reaction
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This note was uploaded on 10/07/2011 for the course BIOL 1001 taught by Professor Minor during the Fall '08 term at LSU.

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EXAM 2 - EXAM2 Chapter6 EnergyFlowinCells WhatisEnergy?...

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