Glycolysis Overview of cellular respiration 4 metabolic stages –Anaerobic respiration 1. Glycolysis –respiration without O 2 –in cytosol –Aerobic respiration

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Glycolysis

GlycolysisOverview of cellular respiration4 metabolic stagesAnaerobic respiration1. Glycolysisrespiration without O2in cytosolAerobic respirationrespiration using O2in mitochondria2. Pyruvate oxidation3. Krebs cycle4. Electron transport chain

C6H12O66O2ATP6H2O6CO2+++(+ heat)2Glycolysis glucose pyruvate2x6C3CBreaking down glucose glyco lysis (splitting sugar)

ancientwhere energy transfer first evolvedtransfer energy from organic molecules to ATPstill is starting point for ALL cellular respirationbut its inefficient generate only 2 ATP for every 1 glucoseoccurs in cytosol3Why does it make sense that this happens in the cytosol?Who evolved first?10 reactionsconvert glucose (6C) to 2 pyruvate (3C) produces: 4 ATP & 2 NADHconsumes:2 ATPnet yield: 2 ATP & 2 NADHglucoseC-C-C-C-C-Cfructose-1,6bPP-C-C-C-C-C-C-PDHAPP-C-C-C G3PC-C-C-PpyruvateC-C-COverviewDHAP = dihydroxyacetone phosphateG3P = glyceraldehyde-3-phosphateATP2ADP2

ATP4ADP4NAD+22Pienzymeenzymeenzymeenzymeenzymeenzymeenzymeenzyme2Pi2H2

41st ATP used is like a match to light a fire initiation energy / activation energy.

Destabilizes glucose enough to split it in two

Glycolysis summary endergonicinvest some ATPexergonicharvest a little ATP & a little NADH

net yield2 ATP2 NADH4 ATPENERGY INVESTMENTENERGY PAYOFF G3PC-C-C-PNET YIELD-2 ATP5Glucose is a stable molecule it needs an activation energy to break it apart.phosphorylate it = Pi comes from ATP.make NADH & put it in the bank for later.

Pi364,5ADPNAD+GlucosehexokinasephosphoglucoseisomerasephosphofructokinaseGlyceraldehyde 3-phosphate (G3P)DihydroxyacetonephosphateGlucose 6-phosphateFructose 6-phosphateFructose 1,6-bisphosphateisomeraseglyceraldehyde3-phosphatedehydrogenasealdolase1,3-Bisphosphoglycerate(BPG)1,3-Bisphosphoglycerate(BPG)12ATPADPATPNADHNAD+NADHPiCH2COCH2OHPOCH2OPOCHOHCCH2OPOCHOHCH2OPOCH2OP OPOCH2HCH2OHOCH2POOCH2OHPO1st half of glycolysis (5 reactions)Glucose primingget glucose ready to splitphosphorylate glucose (hexokinase) molecular rearrangementsplit destabilized glucose (1 DHAP, 1 G3P)6

2nd half of glycolysis (5 reactions)

Payola!Finally some ATP!

78H2O910ADPATP3-Phosphoglycerate(3PG)3-Phosphoglycerate(3PG)2-Phosphoglycerate(2PG)2-Phosphoglycerate(2PG)Phosphoenolpyruvate(PEP)Phosphoenolpyruvate(PEP)PyruvatePyruvatephosphoglyceratekinasephosphoglycero-mutaseenolasepyruvate kinaseADPATPADPATPADPATPH2OCH2OHCH3CH2O-OCPHCHOHO-O-O-CCCCCCPPOOOOOOCH2NAD+NADHNAD+NADHEnergy Harvest G3PC-C-C-PPiPi6 DHAPP-C-C-CNADH productionG3P donates Hoxidizes the sugarreduces NAD+NAD+ NADHATP productionG3P pyruvatePEP sugar donates Psubstrate level phosphorylationADP ATP7Substrate-level Phosphorylation

P is transferred from PEP to ADPkinase enzymeADP ATP

I get it!The Pi camedirectly fromthe substrate!

H2O910Phosphoenolpyruvate(PEP)Phosphoenolpyruvate(PEP)PyruvatePyruvateenolasepyruvate kinaseADPATPADPATPH2OCH3O-OCO-CCCPOOOCH2In the last steps of glycolysis, where did the P come from to make ATP?the sugar substrate (PEP)ATP

78H2O910ADPATP3-Phosphoglycerate(3PG)3-Phosphoglycerate(3PG)2-Phosphoglycerate(2PG)2-Phosphoglycerate(2PG)Phosphoenolpyruvate(PEP)Phosphoenolpyruvate(PEP)PyruvatePyruvateADPATPADPATPADPATPH2ONAD+NADHNAD+NADHPiPi6Glycolysis

glucose + 2ADP + 2Pi + 2 NAD+ 2 pyruvate + 2ATP + 2NADHBut cant stop there!Going to run out of NAD+without regenerating NAD+, energy production would stop!another molecule must accept H from NADHso NAD+ is freed up for another round

PiNAD+G3P1,3-BPG1,3-BPGNADHNAD+NADHPiDHAPraw materials products9

NADHpyruvateacetyl-CoAlactateethanolNAD+NAD+NADHNAD+NADHCO2acetaldehydeH2OKrebscycleO2lactic acidfermentationwith oxygenaerobic respirationwithout oxygenanaerobic respirationfermentationHow is NADH recycled to NAD+?Another molecule must accept H from NADH

recycleNADHalcoholfermentation