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! "#$%&'(!)*+!,-./012345!6! '7-89:!%81;<=>17! ( ! ! ! !"#"$%&'()$*%#+,'(-(.+/&/*+,%&(01"2+34$5( 6%#+,"(!/$75#38+(92+41! CHAPTER 23: Metabolism & Energy Production Learning Objectives: ! 94%*"3(/>(?"4%@/&+32( ! ABCD(34$E,4E$"'(15<$/&53+3'(-(>/$2%F/#( ! 0/EG&+#*($"%,F/#3( ! 0/"#752"3(( ! HAIJ(-(HAIK( ! LAI(-(LAIK;( ! 0/"#752"(A( ! 0+4$+,(A,+<(05,&"D(%&&(M(34"G3( ! =&",4$/#(B$%#3G/$4(01%+#( ! ABC(35#41"3+3(@5()N+<%FO"(C1/3G1/$5&%F/#( ( CH 23 Homework: End of Chapter problems: 20, 22, 24, 26, 28, 32, 34, 36, 40, 42, 46, 48, 50, 52, 56, 60, 64, 74( 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( ;( Metabolism Definition • Metabolism is the sum of all the chemical reactions that take place in an organism. • Catabolism is the breakdown of large molecules into smaller ones; energy is generally released during catabolism. Anabolism is the synthesis of large molecules from smaller ones; energy is generally absorbed during anabolism. • Often, the process is a series of consecutive reactions called a metabolic pathway, which can be linear or cyclic. 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( Metabolism P( Overview Stage [1] – Digestion Stage [2] – Formation of Acetyl CoA Stage [3] – The Citric Acid Cycle Stage [4] – Electron Transport Chain & Oxidative Phosphorylation 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( Q( Metabolism Stage [1] – Digestion 0%$@/15<$%4"3( C$/4"+#3( B$+%,5&*&5,"$/&3( 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( Metabolism 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( R( Stage [2] – Formation of Acetyl CoA S( Metabolism Stage [3] – The Citric Acid Cycle • The citric acid cycle is based in the mitochondria, where the acetyl CoA is oxidized to CO2. • The cycle also produces energy stored as a nucleoside triphosphate and the reduced coenzymes. 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( Metabolism T( Stage [4] – Electron Transport Chain & Oxidative Phosphorylation • Within the mitochondria, the electron transport chain and oxidative phosphorylation produce ATP (adenosine 5 triphosphate). • ATP is the primary energycarrying molecule in the body 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( M( Definition ATP 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( U( Hydrolysis: Energy Released ATP • Hydrolysis of ATP cleaves 1 phosphate group. • This forms ADP and hydrogen phosphate (HPO42!), FIRST PAGES releasing 7.3 kcal/mol of energy. 757 ATP AND ENERGY PRODUCTION O −O ATP AND ENERGY PRODUCTION P O O O− P O− FIRST PAGES O P −O P O− O P O− O P O− O CH2 N N −O P O− H2O N O O N + O− N O N O NHOH 2 O O N O This bond is broken. O NH2 NH2 This bond is broken. O P O CH2 N 757 O NHOH 2 ATP O −O O N OH NADP O N + O− OH N −O P OH − O Pi O N O P O CH2 O Any process, such asP walking, running, swallowing, orNbreathing, is fueled by the release −O − − + most P OH member of a group O of ATP to ADP. ATP is the O from the hydrolysis prominent of “high-energy” molecules, reactive molecules that release energyO−by cleaving a bond during OH OH OH OH hydrolysis. Because ATP contains four negatively charged oxygen atoms in close proximity, the electronic repulsion of the like charges drives ATP ADP the hydrolysis to ADP,Piwhich has fewer negatively 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( VW( charged-(.+/&/*+,%&(01"2+34$5(;#<(=<:( oxygens and therefore less electronic repulsion. Any process, such as walking, running, swallowing, or breathing, is fueled by the release • The reverse reaction, phosphorylation, adds a phosphate group ADP, forming ATP. of energy from the hydrolysis of ATP to ADP. ATP is the most prominent member of atogroup Phosphorylation requiresthat 7.3release kcal/mol of energy. of “high-energy” molecules, reactive molecules energy by cleaving a bond during hydrolysis. Because ATP contains four negatively charged oxygen atoms in close proximity, the CH2 O N N + Hof 2Oenergy NH2 This bond is formed. NH O− O− O− coupled reaction. (b) TP AND ENERGY PRODUCTION + OH This bond is broken. fructose O− H O + 757 O− 2 How much energy is released in the coupled reaction? OH OH NH2 N O P OH − O OH Energy change HPO42−ATP + − fructose 6-phosphate + H2O NH2 +3.8ADP kcal/mol N N Pi N O O Any process, such as walking, running, swallowing, or breathing, is fueled by the release Phosphorylation: Energy Absorbed − − O member of a group of energy from the hydrolysis of ATP to ADP. prominent P O CH2 ATP O P O O P O P O P O CH2 N O O is theNmost N Write the equation for the hydrolysis of ATP to ADP (Section 23.3A). Add together the substances in − of “high-energy” molecules, reactive molecules that release energy by cleaving − − − − − + O P OH a bond during + H2O O O O O O this equation and the given hydrolysis. equation to give the net equation—that is, the equation for the coupled Because ATP contains four negatively charged oxygen atoms in close proximity, the O− reaction. To OH determine energy change, add together the energy changes each step. OHthe overall OH hydrolysis OH to for electronic repulsion of the like charges drives the ADP, which has fewer negatively • Phosphorylation is the reverse reaction, where charged oxygens and therefore less electronic repulsion. O O O ATP N Analysis Solution ATP ADP a phosphate group is added to ADP, forming ATP Pi a. The coupled equation shows overall reaction that combines phosphorylation of fructose • The the reverse reaction, addsthe a phosphate group to ADP, forming ATP. requiring 7.3 ofphosphorylation, energy. Any process, such askcal/mol walking, running, orenergy. breathing, is fueled by the release Phosphorylation requires swallowing, 7.3 kcal/mol of and the hydrolysis of ATP. of energy from the hydrolysis of ATP to ADP. ATP is the most prominent member of a group Cross out compounds that appear of “high-energy” molecules,NH reactive molecules that release energy bybond cleaving a bond during NH2 This ison formed. 2 both sidescharged of the reaction arrows. hydrolysis. Because ATP contains four negatively oxygen atoms in close proximity, the N N N 2− drives the hydrolysis to ADP, which has fewer negatively N of the+likeHPO charges O O O O Oelectronic [1] repulsion fructose fructose 6-phosphate + H2O 4 charged oxygens and therefore less electronic repulsion. − −O N O P O P O P O CH P O P O CH 2 O− N O Phosphorylation requires 7.3 kcal/mol of energy. OH Coupled reaction: −O P OH fructose NH2 ADP + ATP fructose 6-phosphate This bond is formed. P b. The overall energy change is the sum of thei energy changes for each step: N N +3.8 kcal/mol + (–7.3) kcal/mol –3.5reactions, kcal/mol.ATP O of energy. O is a transporter O O By way of=these O O O− P O CH 2 O PROBLEM 23.3 O − N O 2 N − −+ ATP + +H2O ADP HPO 2− HPO42− adds a phosphate O−group Oto O • The[2] reverse reaction, phosphorylation, ADP,Oforming ATP. 4 − N N + −O P O P O P OH O NH ATP 2 N • Energy in ATP when it is synthesized from ADP. 2− is absorbed and stored − − − HPO4 O O O N N + H2O The phosphorylation of glucose to glucose 1-phosphate requires 5.0 to kcal/mol of energy. This • Energy is released when ATP is hydrolyzed ADP. unfavorable the equation for the OH reaction OH can be driven by the hydrolysis of ATP to ADP. (a) WriteOH OH Figureenergy 23.492+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( summarizes and energy changes that occur when ATP is synthesized coupled reaction. (b) How much is releasedthe in reactions the coupled reaction? VV( ADP Pi -(.+/&/*+,%&(01"2+34$5(;#<(=<:( and hydrolyzed. As we learned in Section 6.2, whenATP energy is released in a reaction, the 2– glucose + change HPO4 is reportedglucose 1-phosphate + H2so O the energy change for ATP hydrolysis energy as a negative (–) value, By way of these reactions, ATP is a transporter of energy. is –7.3 kcal/mol. When energy is absorbed in a reaction, the energy change is reported as a positive (+) value, so the energy change for the phosphorylation of ADP is +7.3 kcal/mol. The • Energy absorbed stored in ATP it isdrawn synthesized ADP. Coupled reactions that is use ATP orand coenzymes arewhen often usingfrom a combination of horizontal synthesis of ATP with HPO42– is the reverse of ATP hydrolysis, and the energy changes for • Energy released when ATP is hydrolyzed to products ADP. and curved arrows. Theisprincipal organic reactants and are drawn from left to right with such reactions are equal in value but opposite in sign. a reaction arrow as usual, but additional compounds like ATP and ADP are drawn on a curved Figure 23.4 summarizes the reactions and energy changes that occur when ATP is synthesized arrow. This technique is meant organic substrates of isthereleased reaction, making and hydrolyzed. Asto weemphasize learned in the Section 6.2, when energy in awhile reaction, the Coupled Reactions ATP it clear that other materials neededas23.4 for theATP reaction to occur. energy change isare reported a negative (–) value, so the energy change for ATP hydrolysis Figure Hydrolysis and Synthesis is –7.3 kcal/mol. When energy is absorbed in a reaction, the energy change is reported as a Energy change ADP for ATP OPO O positive (+) value, so the32− energy change the phosphorylation of ADP is +7.3 kcal/mol. The ATP Hydrolysis2– ATP + H2O ADP + HPO42− −7.3 kcal/mol synthesis of ATP with HPO4− is the reverse of ATP hydrolysis, and the energy changes for CH C COO CH3 C COO− such reactions 2are equal in value but opposite in sign. 2− ATP Synthesis phosphoenolpyruvate ADP + HPO4 pyruvate + ATP H2O +7.3 kcal/mol Energy is released. Figure are 23.4pairs ATP Hydrolysis and Synthesis PROBLEM • Coupled23.4 reactions of reactions that occur Energy is absorbed. together. Write each of the following reactions using curved arrow symbolism. Energy change • The energy released by toone is absorbed the other reaction. 2− Hydrolysis HPO + reaction H2O ADPandby +ADP −7.3 kcal/mol23.1) 4 a. reaction of ATP fructose with ATPATP form fructose 6-phosphate (Sample Problem b. reaction of glucose with ATP to form glucose 6-phosphate and ADP 2− ATP energetically Synthesis ADP unfavorable + HPO4 ATPwith + a favorable H2O +7.3 kcal/mol • Coupling an reaction one that releases more energy than the amount required is common in biological Energy is released. Energy is absorbed. reactions. smi02788_ch23_751-777.indd 757 777.indd 757 H2O OH ADP N CH2 O + + 7/8/11 11:37 AM 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( V;( 7/8/11 11:37 AM 7/8/11 11:37 AM Coenzymes Oxidation & Reduction 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( Coenzymes VP( Coenzyme A • Coenzyme A (HS-CoA) is neither an oxidizing nor a reducing agent. • When the thioester bond is broken, 7.5 kcal/mol of energy is released. 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( VQ( Citric Acid Cycle Overview • The citric acid cycle produces high-energy compounds for ATP synthesis in stage [4] of catabolism. 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( Citric Acid Cycle 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( VR( Overview VS( Citric Acid Cycle Steps 1 - 4 • Step [1] reacts acetyl CoA with oxaloacetate to form citrate, and it is catalyzed by citrate synthase. • Step [2] isomerizes the 3o alcohol in citrate to the 2o alcohol in isocitrate; it is catalyzed by aconitase. • Step [3] isocitrate loses CO2 in a decarboxylation reaction catalyzed by isocitrate dehydrogenase. Also, the 2o alcohol of isocitrate is oxidized by the oxidizing agent NAD+ to form the ketone !-ketoglutarate and NADH • Step [4] releases another CO2 with the oxidation of !ketoglutarate by NAD+ in the presence of coenzyme A to form succinyl CoA and NADH. Catalyzed by !-ketoglutarate 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( VT( dehydrogenase -(.+/&/*+,%&(01"2+34$5(;#<(=<:( Citric Acid Cycle Steps 5 - 8 • Step [5] the thioester bond of succinyl CoA is hydrolyzed to form succinate, releasing energy that converts GDP to GTP. • Step [6] succinate is converted to fumarate with FAD and succinate dehydrogenase; FADH2 is formed. • Step [7], water is added across the C=C; this transforms fumarate into malate, which has a 2o alcohol. • Step [8], the 2o alcohol of malate is oxidized by NAD+ to form the ketone portion of oxaloacetate and NADH. The product of step [8] is the starting material for step [1]. 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( VM( Citric Acid Cycle Overall Reaction The main function of the citric acid cycle is to produce reduced coenzymes (NADH and FADH2). These molecules enter the electron transport chain and ultimately produce ATP. 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( Electron Transport VU( Definition • The electron transport chain is a multistep process using 4 enzyme complexes (I, II, III and IV) located along the mitochondrial inner membrane. 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( ;W( Electron Transport Electron Transport Chain • The reduced coenzymes (NADH and FADH2) are reducing agents, and can donate e! when oxidized. • NADH is oxidized to NAD+ and FADH2 is oxidized to FAD when they enter the electron transport chain. • The e! donated by the coenzymes are passed down from complex to complex in a series of redox reactions, which produces some energy. • These e! and H+ react with inhaled O2 to form water. 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( ATP Synthesis ;V( Oxidative Phosphorylation • The electron transport chain provides the energy to pump H+ ions across the inner membrane of the mitochondria. • The concentration of H+ ions in the inter membrane space becomes higher than that inside the matrix creating a potential energy gradient. • To return to the matrix, H+ ions travel through a channel in the ATP synthase enzyme (catalyzes phosphorylation of ADP to ATP). • The energy released as the H+ ions return to the matrix is the energy stored in the ATP molecule. 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( ;;( ATP Synthesis Oxidative Phosphorylation • Each NADH entering the electron transport chain produces enough energy to make 2.5 ATPs. • Each FADH2 entering the electron transport chain produces enough energy to make 1.5 ATPs. • The citric acid cycle produces overall: 3 NADH x 2.5 ATP = 7.5 ATP 1 FADH2 x 1.5 ATP = 1.5 ATP 1 GTP = 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( ATP Synthesis 1 ATP 10 ATP ;P( Oxidative Phosphorylation 92+41'(6%#+,"(!/$75#38+:(!"#"$%&'()$*%#+,'( -(.+/&/*+,%&(01"2+34$5(;#<(=<:( ;Q(