Biochemistry Chapter 3 Notes
Biochemistry Chapter 3 Notes Chem 3375
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This 4 page Class Notes was uploaded by Nancy Ly on Tuesday September 22, 2015. The Class Notes belongs to Chem 3375 at Texas State University taught by Dr. Kerwin in Fall 2015. Since its upload, it has received 28 views. For similar materials see Principles of Biochemistry in Chemistry at Texas State University.
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Date Created: 09/22/15
CHEM 3375 Principles of Biochemistry CHAPTER 3 READING LOG Thermodynamic Principles Before you read What is the purpose of reading this material The purpose of reading this material is to review on principles and laws of thermodynamics What do I already know about this topic 0 Energy is conserved Gibbs free energy G H TS Energy can neither be created nor destroyed While you read Thermodynamics the relationship of various forms of energy and how the energy affects matter ie temperature and pressure System a part of the universe that is of interest Le a reaction vessel or an organism Surroundings the rest of the universe Exothermic process the system releases heat q Endothermic process the system gains heat q State functions quantities that depends only on the state of the system Cyclic process an process in which the system returns to its initial state Enthalpy H U PV 0 V is the volume of the system 0 P is pressure 0 Under constant pressure a condition typical of most biochemical processes the enthalpy change between the initial and final states of a process AH is the easily measured heat that it generates or absorbs Disorder the number of equivalent ways W of arranging the components of the universe Entropy S kBInW disorder 0 KB is the Boltzmann constant 0 Entropy is a state function because it depends only on the parameters that describe a statequot Equilibrium a state in which there is no change in the system forward and backward reactions are exactly balanced AG O Reversible processes any system that becomes progressively disordered its entropy increase as its temperature rises Denature unfolded Native normally folded Exergonic AG spontaneous process Endergonic AG not a spontaneous process must be driven by an input of free energy Substrate reactant AGOf free energy of formation the change in free energy accompanying the formation of 1 mol of the substance in its standard state from its component elements in their standard states After you read A The key points of this reading are With a knowledge of thermodynamics we can determine whether a physical process if possiblequot A system is said to be open closed or isolated according to whether or not it can exchange matter and energy with its surroundings only energy or neither matter nor energy 0 Living organisms which take up nutrients release waste and generate work and heat are examples of open systems if an organism were sealed inside an uninsulated box it would together with the box constitute a closed system whereas if the box were perfectly insulated the system would be isolated First law of thermodynamics energy can be neither created nor destroyed 0 AU U nal Uinitial Cl W 0 U energy 0 Q the heat absorbed by the system from the surroundings random molecular motion 0 W the work done on the system by the surroundings organized motion Work done by the system against an external force is de ned as a negative quantity quotExperiments have invariably demonstrated that the energy of a system depends only on its current properties or state not on how it reached that statequot There is no net charge in energy AU O for any process in which the system returns to its initial state Work and heat is a separate state function because each is dependent on the path followed by a system in changing from one state to another Any combination of only state functions must also be a state functionquot The change of enthalpy in any hypothetical reaction pathway can be determined from the enthalpy change in any other reaction pathway between the same reactants and productsquot Spontaneous processes are characterized by the conversion of order to chaosquot Second law of thermodynamics spontaneous processes occur in directions that increase the overall disorder of the universe The laws of random chance cause any system of reasonable size to spontaneously adopt its most probably arrangement the one in which entropy is a maximum simply because this sate is so overwhelmingly probablequot For any constant energy process AU O a spontaneous process is characterized by ASgtOquot Any spontaneous process must cause the entropy of the universe to increase 0 ASsystem ASsurroundings ASuniversegtO Second law of thermodynamics The entropy of the universe tends towards a maximum A system can only be ordered at the expense of disordering its surroundings to an even greater extent by the application of energy to the systemquot Eating is as much a way fo acquiring order as it is of gaining energy For spontaneous processes nal oASz fd I initial T is the absolute temperature at which the change in heat occurs 0 The universe s entropy change in any real process is always greater than its ideal reversible valuequot 0 Which means that when a system leaves from and then returns to its initial state via a real process the entropy of the universe must increase even though the entropy of the system does not change Gibbs free energy G AH TAS is the required indicator of spontaneity for constant temperature and pressure processes 0 A650 is the criterion of spontaneity for the constant T and P conditions that are typical of biochemical processes 0 AG for a biological process represents its maximum recoverable work 0 An enzyme can only accelerate the attainment of thermodynamics equilibrium it cannot promote a reaction that has a AG The relationship between the concentration and he free energy of a substance A o GA ngRTInlA Where GA is the partial molar free energy or the chemical potential of A G is the partial molar free energy of A in standard state 39 Risthe gas constant A is the molar concentration of A 0 Le Chatelier s principle states any deviation from equilibrium stimulates a process that tends to restore the system to equilibrium All isolated systems must therefore inevitably reach equilibrium 0 The additivity of free energy changes allows an endergonic reaction to be driven by an exergonic reaction under the proper conditions 0 As long as the overall pathway reaction sequence is exergonic it will operate in the forward direction Tahiti 32 Waria en eff Eeaetien EiItrtlit a39lirlrit 395r Sign eff 6 with tllrt Signs 139 IM ME as iii3 M3 TEE i reaetien ie truth enthalpieally favered exethermiej an entrepiea y featured It ia aperita eeue errerge iej at all IE l Et li E reaetien ie enthalpieally fairereri but entrepieallji39 epjreae It ie ape tarieeua an at temperatures treiew T HEM reaetien i5 enthalpieajly eppneae e dethermiejl but entreeiea y featured It ia epmrrtanee ue erin at temperaturee ebeue T MIME reaetien ie bath errthalpieally 311d errtrepieallji39 eppeee It i5 eeape tarieeua e derge iejl at all temperatures B One topic I understood well is The rst and second law of thermodynamics C One topic I struggled with is Gibbs free energy and how to solve for problems that require the use of the formula and other formulas associated with it D These are the questions about C or another topic that I still have after reading the material 0 How would you use the equations for AG AGquot and AGO E I think that consulting these resources can help me answer these questions or get additional information on this topic 0 Examples in the biochemistry book 0 More examples onine