Biochemistry SG.pdf

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Biological Sciences
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M.G Cumsky

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1Biochemistry Study GuideUCI Winter 13 IWhat is metabolism A The chemistry of life B Categories of metabolism1 CatabolismNutrient macromolecules Carbs fats proteinsCO HO NH waste 223 2 Anabolism Biosynthesis Synthesis of macromolecules from precursors Requires energy 3 Common intermediates connect the two categories This is important because it promotes regulation and allows the pathways to be highly efficientFigure 1 Catabolic versus AnabolicC Roles of Metabolism 2 Generates chemical energy ATPGeneratessynthesizes biosynthetic precursorsAmino Acids Sugars Fatty Acids NucleotidesSynthesis of MacromoleculesProteins Nucleic acids lipids cell structures etcSynthesis and degradation of special products Steroids degrade toxins etcD Modes of Metabolic Regulation1 Compartmentalization Specific reactions occur in specific organelles Majority in cytosol and mitochondria Segregates opposed reactionsTable 1 Mitochondria CompartmentsCompartmentContainsOuter Membrane Permeable membrane to small moleculesionsInner MembraneImpermeable Res etranslocase ATP synthase FMatrixpyruvate DH citric acids cycle enzymes fatty acid enzymes AA enzymes DNA ribosomes many soluble metabolic intermediates ATP ADP P2 Stepwise Pathways3 Regulation Positive regulators upregulate speed up reaction to make ATPNegative regulators lower ECExpression of important metabolic genes Hormonal control transcriptionaltranslational control Ultimately metabolism is regulated through the control ofAmount of enzymes Their cat activities Accessibility of substratesE Energy Charge EC ECATP05ADPATPADPAMP EC1 All ATP EC0 All AMPFThe main purpose for continual input of free energyi Performance of mechanical work in muscle contractioncellular movements ii Active transport of moleculesionsiii Synthesis of macromoleculesother biomolecules from simple precursors3GTwo criteria required for individual reactions to form a specific pathway i individual reactions must be specificii The set of reactions must be thermodynamically favored overall Gexergonic A thermodynamically unfavorable reaction can be coupled with a favorable one to drive the synthesis forwardHActivated Carriers in Metabolic PathwaysAn OverviewFundamental Terminology1Activated Carriers of Electrons for Fuel Oxidation In aerobic organismsO is the ultimate e acceptor in the oxidation of fuel 2molecules NAD a pyridine nucleotide is a major e carrier in oxidation of fuel molecules Reduced form NADH Oxidized form NAD 2Activated Carrier of Electrons for the Synthesis of BiomoleculesStarting materials are usually more oxidized than the productstherefore reductionATP is needed reductive biosynthesisNADPH is the major e donor NADPH versus NADHOne e carrier is phosphorylated and one isntNADPH is exclusively for reductive biosynthesis versus NADH is used for generation of ATP The extra phosphoryl group of NADPH is a tag that enables enzymes to distinguish between Potential es to be used in anabolismcatabolism 3 Activated Carrier of TwoCarbon Fragments CoASH Coenzyme A is a carrier of acyl groupsAcyl groups are important in Catabolismoxidation of FAsAnabolismsynthesis of membrane lipidsAcCoA hasacetyl group transfer potential bc transfer of the acetyl group is exergonic IIGlycolysis and GluconeogenesisALouis PasteurBBuchnerCHarden and Young DEmbden Myerhof Warburg Parnas Von EulerChelpinEGlycolysis Glycolysis is carried out in muscles to produce lactic acid It is also carried out in the brain and nervous tissue Pathway releases energy ATPLow NADNADH ratio There are two stages1 Glucose is converted to F16BP 3 steps 1 6C fragment is cleaved to 2 3C fragments 2 ATP is generated when the 3C fragments are oxidized to pyruvate Pyr Steps 610 are repeated 2xFGluconeogenesis
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