GLYCOLYSIS. TransporterLocationCharacteristics Na + /glucose transporters GutGlucose-sodium symport Na+ independent facilitated diffusion-transporters

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  • GLYCOLYSIS

  • GLUCOSE TRANSPORTERS

    TransporterLocationCharacteristicsNa+/glucose transportersGutGlucose-sodium symportNa+ independent facilitated diffusion-transportersGLUT1All cells, RBCs, brainLow KmGLUT2Liver, b cells of pancreas, kidney, intestineHigh KmGLUT3Brain, most cell typesLow KmGLUT4Muscle, adipose tissueInsulin-dependent translocation to plasma membraneGLUT5Intestine, liverFructose absorption

  • METABOLIC FATES OF GLUCOSECatabolized to produce ATP Stored as glycogen in liver and musclesConverted to fatty acids and stored as triglycerides in adipose tissue

  • CARBOHYDRATE CATABOLISM

  • GLYCOLYSISA two-phase pathway in whichGlucose is oxidized into pyruvateNAD+ is reduced to NADH + H+ATP is synthesized by substrate-level phosphorylationPyruvateMoves on to the Krebs cycle in an aerobic environment Is reduced to lactate in an anaerobic environment

  • GLYCOLYSIS The phasesI. Energy investment phaseII. Energy generation phase

  • GLYCOLYSISStep I.GLUCOSE

  • Hexokinase/GlucokinaseHexokinaseFound in most tissuesBroad specificityLow KmLow Vmax

    Makes glucose available to tissues at low blood glucose levels

  • Hexokinase/GlucokinaseGlucokinaseFound in liver and b cells of pancreasBroad specificityHigh KmHigh VmaxClears glucose from blood after meals and at blood glucose levels > 100 mg/dl

  • GLYCOLYSISStep II.GLUCOSE 6- PHOSPHATE

  • GLYCOLYSIS Step III.FRUCTOSE 6- PHOSPHATE

  • GLYCOLYSIS Steps IV, V.FRUCTOSE 1, 6- BISPHOSPHATETriose phosphate isomerase

  • GLYCOLYSIS Step VI.GLYCERALDEHYDE 3-PHOSPHATE

  • GLYCOLYSIS Step VII.1,3- BISPHOSPHO-GLYCERATE

  • SUBSTRATE-LEVEL PHOSPHORYLATIONHigh-energy phosphate groups are transferred directly from phosphorylated substrates to ADP

  • 2, 3- BISPHOSPHOGLYCERATE

  • PiARSENATE POISONINGGLYCERALDEHYDE 3-PHOSPHATE1,3- BISPHOSPOGLYCERATE3- PHOSPHOGLYCERATEGlyceraldehyde 3-phosphate dehydrogenasePiNAD+H+ + NADHADPATPARSENATEGLYCOLYSIS CONTINUES ENERGY IS DEPLETED

  • GLYCOLYSIS Step VIII.3- PHOSPHO-GLYCERATE

  • FLOURIDEGLYCOLYSIS Step IX.2- PHOSPHO-GLYCERATE

  • GLYCOLYSIS Step X.PHOSPHOENOLPYRUVATE

  • GLYCOLYSIS: SUMMARYGLUCOSE + 2NAD+ +2Pi + 2ADP2 PYRUVATE + 2NADH + 2H+ + 2ATP + 2H2O

  • THE FATES OF PYRUVATEANAEROBIC CONDITIONSReduced to lactate(In RBCs, the kidney medulla, lens and cornea of the eye, testes, leukocytes and in muscles during intensive exercise)AEROBIC CONDITIONSoxidative decarboxylation to Acetyl CoA (in tissue with high oxidative capacity e.g. cardiac muscle, brain etc. )

  • ANAEROBIC CONDITIONSPYRUVATE

  • ANAEROBIC GLYCOLYSISGLUCOSE + 2Pi + 2ADP2 Lactate + 2ATP + 2H2O + 2H+

  • AEROBIC GLYCOLYSISPYRUVATE

  • For each molecule of glucose entering glycolysis, two molecules of acetyl CoA enter the Krebs cycle

  • REGULATION OF GLYCOLYSISHexokinase/GlucokinasePhosphofructokinasePyruvate Kinase

  • REGULATION OF HEXOKINASEGLUCOSEGLUCOSE 6- PHOSPHATEATPADPHexokinase

  • GLUCOSEGLUCOSE 6- PHOSPHATEATPADPGlucokinaseFRUCTOSE 6- PHOSPHATEREGULATION OF GLUCOKINASE

  • NucleusGKRPGLUCOSEGlucokinaseFRUCTOSE 6- PHOSPHATEGKGlucokinaseREGULATION OF GLUCOKINASE

  • REGULATION OF PHOSPHOFRUCTOKINASE 1FRUCTOSE 6- PHOSPHATEFRUCTOSE 1,6- BISPHOSPHATEPhosphofructokinase 1

  • REGULATION OF PHOSPHOFRUCTOKINASE 1FRUCTOSE 6- PHOSPHATEFRUCTOSE 2,6- BISPHOSPHATEPhosphataseWell fed state InsulincAMPprotein kinaseStarvation Glucagon cAMP Protein kinasePhosphofructokinase 2KinaseP

  • REGULATION OF PYRUVATE KINASEFRUCTOSE 1,6- BISPHOSPHATEPYRUVATEPyruvate kinase+

  • REGULATION OF PYRUVATE KINASEPHOSPHOENOLPYRUVATEPYRUVATEStarvation Glucose Glucagon cAMP Protein kinase APyruvate kinasePGLUCONEOGENESIS

  • GLYCOLYSIS AND OTHER METABOLIC PATHWAYS

  • THANK YOU!