Glycolysis vs Gluconeogenesis Glycolysis Gluconeogenesis Glucose Glycolysis occurs mainly in the muscle brain phosphate nexokinase starvation Jose VIgo4roUS exercise physiologically aclds no fatty acids Allows generation stores are depleted of glucose when glycogen Operate in opposite direction necessary Brain nervous system and red blood cells 2 pyruvate 4 ATP 2 GTP 2 NADH 2H Reversible reactions both pathways Differentenzymes in differentpathways 4 H 0 Glucose 4 ADP 2GDP 6Pi 2 NAD No ATP generated during gluconeogenesis End productof one Is the starting compound of the other Opposing pathways thatare both thermodynamically favorable Gluconeogenesis occurs mainly in the liver eventoffutilearevertegnoseare Gifferentialsregulate irbtusbanrubinthe Irreversible reaction of glycolysis bypassed in gluconeogenesis Iseusetra avianinterestinent Process occurs during periods of fasting starvation low carbohydrate are netnee Ubiquitous process plants animals fungi bacteria other microorganisms Mammals gluconeogenesis is believed to be restricted to the liver Metabolic pathway results in generation of glucose from certain the kidney the Intestine muscle New evidence suggests thatit Any compound thatcan be converted to either pyruvate or oxaloacetate can therefore serve as starting material for gluconeogenesis alanine aspartate path from pyruvate to phosphoenolpyruvate leads through oxaloacetate Animals cannot produce glucose from fatty colds Animals produce glucose from sugars proteins non carbohydrate carbon substrates occurs in astrocytes of the brain Begins in mitochondrial diets Intense exercise citric acid cycle Intermediate of 2 Pyruvate Pyruvate Flucogenic Glycerol amino acIds Blood CHIC I Lactate 3 phospho CO2 fixation Triacyl glycerols can also yield 3 or 4 carbon fragments plants photosynthetic bacteria are uniquely able to convertco to carbohydrates Calvin cycle Steps 1 2 Pyruvate to Phosphoenolpyruvate Bicarbonate Pyruvate 8 10 AbP Pi no c CH carseat Guanosine attentionerata carboxyminera 0 P0 CH2 C C00 Phosphoenolpyruvate FirstGluconeogenic Steps Travel through Mitochondria 1ststep pyruvate carboxylase converts pyruvate to oxaloacetate Carboxylation using a blotin factor Requires transportinto the mitochondria 2nd Step Phosphoenolpyruvate carboxykinase converts oxaloacetate to PEP phosphorylation from GTP decarboxylation occurs in mitochondria cytosol depending on the organism Carbon is added immediately removed from structure Blotin Is a CO2 Carrier Long blotinyl Lys tether moves CO2 from site 1 to site 2 HC05 at app isacat at pyruvate I pyruvate carboxylase Pyruvate Carboxylase Reaction cofactor blottn covalently attached to enzyme through amide linkage to s amino group of Lys residue forming bloting enzyme CO2 Carboxykinase cytosolic S PEPS Catalytic Site 1 bicarbonate on is converted to Co atthe expense of ATP Reaction occurs 1n2 phases which occur at 2 differentsites in the enzyme minerariesministrarisa biotinanocossidechain cattained then carriesconotcurbobiotingienee CO2 reacts with biotin forms carboxybloting enzyme Long arm composed to catalytic site 2 enzyme surface CO2 Is released reacts with pyruvate forms oxaloacetate regenerating blotinyl enzyme Flexible arms Intermediates between enzyme active sites Lactate Selectively permeable Inner mitochondrial membrane Blotin dependentcarboxylation reactions those catalyzed by proplony Malate PEP pyruvate permeable Oxaloacetate cannotescape CoA carboxylase acetyl CoA carboxylase Oxaloacetate can be utilized in citric acid cycle Krebs cycle Pathways depend on the availability oflactate or pyruvate the oxaloacetate can be converted to PEP or malate to allow transport to cytosol for gluconeogenesis cytosolic requirements for NADHfor gluconeogenesis