biol 1201-exam 2

biol 1201-exam 2 - Exam 2 Chemical Reaction Occur anytime...

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Exam 2 Chemical Reaction Occur anytime two or more atoms, ions, or molecules collide in such a way that they produce a new substance How do cells organize and control the chemical reactions that support life? Metabolic Transformation -Chemical reactions -Small steps -Controlled processes -Each step controlled by a protein catalyst -Enzyme Biological chemical reactions -Regulated by proteins catalysts-enzymes -Synthesis of energy carrier molecules to store energy, transport it from place to place, regulate its flow -Couple reaction together so that unfavorable reaction can occur at the expense of reactions that release energy Enzymes -Protein catalysts -Not used up -Specific reaction require specific enzymes -Enzymes lower activation energy barrier -Enzymes speed up reaction 10^8-10^20 times faster -Do not reverse an energetically unfavorable reaction Thermodynamics -Study of the energy relationships of a system Free Energy -Energy that is free and available to do work Gibbs (free) Energy and Chemical Reactions Spontaneous- can occur without adding additional energy Releases Gibbs energy (exergonic) Non-spontaneous Requires gibbs energy (endergonic) Energy -Potential -Kinetic First Law of Thermodynamics -Within any closed system the total amount of energy remains constant Second Law of thermodynamics -All spontaneous processes result in an increase in randomness and disorder in the universe -And consequently in a loss of localized concentrations of energy -Entropy is increasing
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-You must define “the system” -A closed 9isolated) system -The earth is not a closed system Chemical Reactions -Endergonic (endothermic)—require net input of energy (heat0 to proceed -Exergonic 0exothermic)—energy (heat) -Only proceed spontaneously in the “downhill” reaction -Downhill=exergonic direction -Negative delta g -Energy is released -Reactants -Products -Energetics Example of exergonic reaction is burning coal -“B”=delta G -Delta G -Determine whether the reaction proceed to the right Change in energy=change in heat energy-(temp) change in the entropy Burning of coal -Exergonic (exothermic) -Coal and oxygen -Reactants -Wouldn’t burn all semester -Activation energy barrier -Delta G double dagger -“A” represents the activation energy barrier -The height of this barrier determines the rate of the reaction -Energy required for the favorable position of the reactants so the reaction can occur -Transition state Enzymes accelerate chemical reactions -Reaction rates are increased because enzymes loser the activation energy barrier -Enzymes cannot reverse energetically unfavorable reaction -They do not make a reaction go uphill Enzymes accelerate chemical reaction -The activation energy barrier is lowered because the enzyme positions the reactants in a conformation more favorable for the chemical reaction to occur Activation Energy -Delta G double dagger -Energy necessary for reaction to occur -Temperature is a measure of how many of molecules will have achieved the activation energy Temperature -Measure of the average kinetic energy of the molecules of a substance
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biol 1201-exam 2 - Exam 2 Chemical Reaction Occur anytime...

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