CH7 Energy and Metabolism part1

CH7 Energy and Metabolism part1 - CHAPTER 7 ENERGY and...

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Unformatted text preview: CHAPTER 7: ENERGY and METABOLISM Energy is The capaciTy To do work (2 change in The sTaTe or moTion of maTTer) 1) PoTenTial energy is sTored energy due To posiTion or sTrucTure 'Chemical energy - poTenTial energy sTored in chemical bonds 'ConcenTraTion gradienT — orderly sTaTe wiTh a region of [higher] and a region of [lower] 2) KineTic energy is The energy of moTion as poTenTial energy is used (29 elecTriciTyr lighT, heaT) 1 POTENTIAL KiNETIC Energy 01 position Energy of motion The potential energy is Transformed To kinetic energy pushing The arrow - Figure 7-1 p 153 THERMODYNAMICS Thermodynamics is The sTudy of energy and iTs TransformaTions - Figure 7-2 p 154 SysTem - objecT being sTudied Bl°l°9lcal warms e9 reacTion, cell, ecosysTem are Open Sys ems fR exchange Surroundings - resT of The universe aparT from sysTem Surroundings (a) A closed system does (b) An open system exchanges not exchange energy with energy with its surroundings. its surroundings. LAWS of THERMODYNAMICS J.W Gibbs (1839-1903) - one of The founders of Thermodynamics FirsT Law of Thermodynamics - energy can neiTher be creaTed nor desTroyed; tie energy is conserved -Energy can only be Transferred and Transformed -Organisms musT capTure energy from environmenT Second Law of Thermodynamics — whenever energy is Transformed, some usable energy (6) is converTed inTo heaT ThaT disperses inTo The surroundings; universe always Tends Toward greaTer disorder/randomness °EnThalpy (H) — ToTal poTenTial energy (bond energy) of a sysTem -EnTropy (S) — measure of disorder or randomness (heaT - unusable energy) °Free energy (6) — energy available To do work -TemperaTure (T) H=G+TS,so...G=H—TS To express whaT happens in a chemical reacTion: (A : change): Free energy change, AG : AH - T AS EXERGONIC and ENDERGONIC REACTIONS AG : Gflnal _ GlanlOl Gfm‘ < 6 01.50 AG<O (-15.6) iniTi An Exergonic reacTion releases free energy Gives up enThalpy, enTropy increases, or boTh Endergonic reacTion — gain in free energy AG : Gfinal ' GiniTial Gfinol > GinifiaI-"50 AG>O (+56) Energy supplied from The surroundings Reactants AG is negaTive Free energy decreases 1 Products Free energy (G) —> (a) In an exergonic reaction, there is a net loss of free energy. The products have less free energy than was present in the reactants, and reaction proceeds spontaneously Course of reaction —|> Prod ucts T Free energy increases Free energy (G) —> AG is posiTive Reactants — Course of reaction —a- (b) In an endergonic reaction, there is a net gain of free energy. The products have more free energy the than was present in the reactants. COUPLED REAC'ITONS - In coupled reactions, on exergonic reaction supplies the energy required to drive an endergonic reaction: A—>B A6 2 +209 kJ/mol C—>D A6 = -33.5 kJ/mol Overall A6 = -12.6 kJ/mol ° In cells, energy-releasing (exergom'c) processes drive energy-requiring (endergom’c) processes ENTROPY and DIFFUSION The Tendency of entropy to increase can be used to perform work - Figure 7-4 p 156 Concentration gradient Exergonic (process occurs spontaneously) (a) A concentration (b) When molecules gradient is a form of are evenly distributed, potential energy. they have high entropy. Orderly state with a region of Gradient is degraded as [high] and a region of [lower] particles move about randomly Adenine ATP consists of adenine, ribose, NH2 and 3 phosphate groups and A hydrolysis of ATP is exergonic and 1- yields ADP and inorganic phosphate Figure 7-5 p 158 Phosphate groups o 0 0 | P | —o-- P—O~P—O O O _ 0— OH OH Adenosine triphosphate (ATP) Hydrolysis H 0 Hydrolysis of ATP is exergonic: GMT? 2 ATP + H20 a ADP + Pr‘ A6 = -32kcaI/mo| ATP Phosphorylation is the Transfer of a phosphate group to another molecule OH OH ADP — remaining molecule lgnrgahnic after phosphate is removed P °3% 3‘9 Phosphorylation reaction by ATP couples the exergonic hydrolysis of ATP with endergonic processes fl?) Motor protein Protein moved Mechanical work — ATP phosphorylates motor proteins Membrane Solute transported Transport work — ATP phosphorylates transport proteins @ N muth fifia Heaclams: Glutamic acid Product (gluten-line) and ammonia made Chemical work — ATP phosphorylates key reactants ATP LINKS ENDERGONIC and EXERGONIC REACTIONS EXergonic reactions Catabolic pathways supply energy to drive endergonic formation of ATP from ADP (release. energy) 'l' . ATP:ADP 10:1 Anabolic pathways are supplied with energy (require energy) from the hydrolysis of ATP Endergonio reactions ELECTRON CARRIERS: ENERGY TRANSFER in REDOX REACTIONS Electron carrier's become reduced by accepting electrons (and H) - Figure 7-7 p 160 NAD+ (oxidized) NADH (reduced) Energy stored in bonds Energy Transferred between X and H to NADH w/ e- and H Iz‘— +IXI+H| o Nicolinamide l Nicotinamide adenine dinucleotide (NAU) is an o _P_O acceptor molecule: two 2— and one proton are added: WWW NH ><H2 + NAD+ —> x + NADH + H+ o l 2 c N N¢ \C/ \ Adenine O —P—o l ll CH — Ho 6 / Phosphate When NAD+ is reduced, it temporarily stores free energy transferred during the redox reactions ...
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