Lecture 14 Chapter 15 Metabolism 1 Outline Metabolism ATP as the universal currency of free energy Coupled ReacBons AcBvated carriers RegulaBon of metabolic processes 2 What is Metabolism The complex of physical and chemical processes occurring within a living cell or organism that are necessary for the maintenance of life MoBon AcBve transport Biosynthesis anabolism Signal ampli caBon ATP ADP Photosynthesis autotrophs OxidaBon of fuel molecules catabolism chemoheterotroph Hydrocarbon Fuels fossil fuel biofuel glucose Contain potenBal energy that can be released by oxidaBon C6H12O6 6 O2 6 CO2 2880 kJ mol 6 H2O 6 CO2 30 ATPs 6 4 H2O Energy is released from glucose in a stepwise fashion forming ATP 30 32 ATP 5 Free Energy Released by OxidaBon of single carbon compounds 6 Two main types of Cellular Fuel 7 OxidaBon ReducBon reacBons Overview ReducBon Gain of e loss of oxygen gain of hydrogen Aox Bred Ared Box OxidaBon Loss of e gain of oxygen loss of hydrogen 8 Catabolism Metabolism Anabolism High Enthalpy Low Entropy Higher free energy OxidaBon of carbon fuel e FADH2 NADH e e e e e e e NADH Low Enthalpy High Entropy Lower free energy 9 10 The stages of catabolism 11 Adenosine 5 Triphosphate ATP Adenine base 2 Phospho ester bond Ribose sugar Phosphate tail Phosphoric Anhydride Linkages Phosphoryl Groups with High Transfer PotenBal in Adenosine NucleoBdes Hydrolysis of Phosphoric Acid Anhydrides is Highly Favorable ATP G 30 5 kJ mol 1 Orthophosphate Pi ADP 14 J G 45 6 kJ mol 1 pyrophosphate PPi 15 Hydrolysis of Pyrophosphate Is Also Thermodynamically Favorable pyrophosphate PPi J G 33 6 kJ mol 1 Pi H Pi H Three ways to make ATP in Eukaryotes 1 Substrate level phosphorylaBon Phosphate is transferred to ADP in a coupled reacBon involving from a molecule with an high phosphoryl group transfer potenBal 2 OxidaBve phosphorylaBon during Cellular respiraBon by ATP phosphatase 3 CreaBne kinase 17 Molecules with High Phosphoryl Group Transfer PotenBal 18 Coupled ReacBon For ProducBon of ATP Substrate level PhosphorylaBon ReacBons 1 and 2 are coupled 1 PEP H2O pyruvate Pi G 62 2 kJ mol 2 ADP Pi ATP H2O G 30 5 kJ mol 3 PEP ADP pyruvate ATP Overall G 31 5 kJ mol G overall G reacBon 1 G reacBon 2 If the net G value G overall is su ciently negaBve forming the products eg pyruvate and ATP is an exergonic process Molecules with High Phosphoryl Group Transfer PotenBal 20 The Large NegaBve Free Energy Change of ATP Hydrolysis Drives many Unfavorable ReacBons in the Cell Example PhosphorylaBon of glucose is driven by hydrolysis of ATP ATP H2O ADP Pi G reacBon 1 30 5 kJ mol glucose Pi G 6 P H2O G reacBon 2 14 kJ mol glucose ATP G 6 P ADP G overall 16 5 kJ mol Coupled reacBons Molecules with High Phosphoryl Group Transfer PotenBal 22 Three ways to make ATP in Eukaryotes 1 Substrate level phosphorylaBon Phosphate is transferred to ADP in a coupled reacBon involving from a molecule with an high phosphoryl group transfer potenBal 2 OxidaBve phosphorylaBon ATP phosphatase 3 CreaBne kinase 23 Sources of ATP during Excercise IniBal pool ATP Anaerobic 24 Two important properBes of high energy compounds 1 Transient forms of stored energy 2 Thermodynamically unstable Favorable spontaneous 3 KineBcally stable Does not hydrolyze unpredictably 25 The High Phosphoryl transfer PotenBal of ATP results from structural di erences between ATP and its hydrolysis Products 1 ElectrostaBc Repulsion 2 Resonance Stability 3 StabilizaBon due to hydraBon 4 Increased entropy 26 Hydrolysis of ATP Causes the Relief of Charge Repulsion 27 Resonance Structures of Orthophosphate Pi 28 There are fewer resonance structures available to the phosphate of ATP than to free orthophosphate 29 Hydrolysis of ATP Increases Entropy ATP H2O Pi O O O P OH H O P O P OR O ADP O O O 30 What is the Daily Human Requirement for ATP ResBng human consume about 40 kg of ATP in 24 hours and up to 0 5 kg per minute of strenuous exercise This is equivalent to 60 kg for a 2 hr run The typical adult human body contains 50 100 g of ATP ADP Thus each ATP molecule must be recycled nearly 1300 Bmes per day The typical ATP molecule is consumed within 1 min of its producBon 31 AcBvated Carriers during Catabolism ADP ATP NAD NADH FAD FADH2 FMN FMNH2 ReducBon of NAD hpp classes midlandstech edu carterp courses bio225 chap05 lecture3 htm 33 DehydrogenaBon ReacBon reduced oxidized oxidized reduced 1 H 1 e 1 H 1 e H hydride 2 e 1 H or H 1 e Error on p 257 of text says hydrite H 2 e 34 NicoBnamide Adenine DinucleoBde NAD NAD Collects Electrons Released in Catabolism H oxidized reduced 35 ReducBon of FAD FMN or FMN or FMNH2 36 FAD Flavine Adenine DinucleoBde Ribo avin a water soluble vitamin Vit B Isoalloxazine ring D ribitol 2 37 FMN an electron carrier component of the ETC Isoalloxazine ring D ribitol 38 AcBvated Carriers during Anabolism ADP ATP NADP NADPH 39 ReducBve Biosynthesis 2 NADPH H 2 NADP 40 The structure of nicoBnamide adenine dinucleoBde phosphate NADP 41 AcBvated Carrier of Acyl Group Coenzyme A CoA or CoASH Vit B5 ADP 42 43 Two characterisBcs are common to acBvated carriers 1 The carriers are kineBcally stable in the absence of speci c catalysts 2 The metabolism of acBvated groups is accomplished with a small number of carriers 44 B3 B5 B7 B9 45 RegulaBon of Glucose Metabolism Normal blood levels 80 to 110 mg dL 46 Diabetes Type 1 Insulin Dependent Blood sugar remains high X 47 Diabetes Type Type 21 Insulin Dependent Insulin Independent Blood sugar remains high X X 48 RegulaBon of Metabolic Pathways 1 Amounts of enzyme are controlled 2 Accessibility to substrates is regulated 3 CatalyBc acBvity is regulated PospranscripBonal modi caBon of enzymes Allosteric regulaBon 4 Organized into pathways 49 Metabolic Pathways carbohydrates nucleoBdes Lipids Amino acids 50 Steady State Flow Flow oof f mMetabolic etabolic pPathway ux athways ux 51 Reversible Pathway A B Not at equilibrium C D E equilibrium 52 Reversible Pathways Cannot be Independently Regulated A B equilibrium C D Not at equilibrium E 53 Reciprocal Pathways Glycolysis C Glucose A B E D Pyruvate F Gluconeogenesis 54 The energy status of the cell is oten an important regulator of enzyme acBvity 55 For each individual pathway Energy charge regulates metabolism 56 Learning Goals Be able to de ne metabolism IdenBfy the factors that make ATP an energy rich molecule Explain how ATP can power reacBons that would otherwise not take place Describe the relaBon between the oxidaBon state of a carbon molecule and its
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