2 Pyruvate Oxidation Conversion to acetyl–CoA Catalyzed by pyruvate dehydrogenaseDecarboxylation - gives CO2 and aldehyde (uses thiamine pyrophosphate)Oxidation - gives acetyl group (uses FAD and NAD+ , makes NADH)Transfer to CoASH (uses lipoic acid)
3 Citric Acid Cycle Overview In the citric acid cycle,Acetyl (2C) bonds to oxaloacetate (4C) to form citrate (6C).Oxidation and decarboxylation reactions convert citrate to oxaloacetate.Oxaloacetate bonds with another acetyl to repeat the cycle.
4 Citric Acid Cycle The citric acid cycle (stage 3) Operates under aerobic conditions only.Oxidizes the two-carbon acetyl group in acetyl CoA to 2CO2.Produces reduced coenzymes NADH and FADH2 and one ATP directly.
13 An acetyl group bonds with oxaloacetate to form citrate Two decarboxylations remove two carbons as 2CO2Four oxidations provide hydrogen for 3NADH and one FADH2.A direct phosphorylation forms GTP (ATP).
14 Overall Chemical Reaction for the Citric Acid Cycle acetyl-SCoA + 3NAD+ + FAD + GDP + Pi + 2H2O2CO2 + 3NADH + 3H+ + FADH2 + HS-CoA + GTPOne turn of the citric acid cycle produces:2 CO GTP (1ATP)3 NADH HS-COA1 FADH2
15 Citric Acid Cycle Conversion of 3 alcohol into 2 alcohol: Now able to be oxidizedo
16 Regulation of Citric Acid Cycle The reaction rate forthe citric acid cycleIncreases when high levelsof ADP or NAD+ activateisocitrate dehydrogenase and-ketoglutarate dehydrogenaseDecreases when high levelsof ATP or NADH inhibitisocitrate dehydrogenase.Decreases when high levelsof NADH or succinyl–CoAinhibit -ketoglutarate dehydrogenase.Formation of acetyl–CoA from pyruvate (catalyzed by pyruvatedehydrogenase) also activated by ADP and inhibited by ATP and NADH.
18 FMN (Flavin mononucleotide) FMN coenzymeContains flavin, ribitol,and phosphate.Accepts 2H+ + 2e- to form reduced coenzyme FMNH2.
19 Coenzyme Q (Q or CoQ) Coenzyme Q (Q or CoQ) is A mobile electron carrier derived from quinone.Reduced when the keto groups accept 2H+ and 2e-
20 Cytochromes Cytochromes (cyt) are Proteins containing heme groups with iron ions.Fe3+ + 1e Fe2+Abbreviated as cyt a, cyt a3, cyt b, cyt c, and cyt c1.
21 Electron Transport Chain Cytc12 NADH + 2 H+ + O NAD H2O2 FADH2 + O FAD H2O
22 Chemiosmotic Model of Electron Transport During electron flow Complexes I, III, and IV pump protons into theintermembrane space creating a proton gradient.Protons pass through ATP synthase to return to the matrix.The flow of protons through ATP synthase provides the energyfor ATP synthesis (oxidative phosphorylation).
23 ATP Synthase In ATP synthase Protons flow back to the matrix through a channel in the F0 complex.Proton flow provides the energy that drives ATP synthesis by the F1 complex
24 ATP from Electron Transport From NADH (Complex I) providessufficient energy for 3ATPsNADH + 3ADP + 3Pi NAD ATPFrom FADH2 (Complex II) providessufficient energy for 2ATPsFADH ADP + 3Pi FAD + 2ATP
25 Regulation of Electron Transport The electron transport system is regulated byHigh levels of ADP and NADH that activateelectron transport.Low levels of ADP, Pi, oxygen, andNADH that decrease electron transport activity.
26 ATP from Glycolysis Reaction Pathway ATP for One Glucose Activation of glucose ATPOxidation of 2 NADH (as FADH2) 4 ATPDirect ADP phosphorylation (two triose) 4 ATP6 ATPSummary:C6H12O pyruvate + 2H2O + 6 ATPglucose
27 ATP from Two Pyruvates Under aerobic conditions 2 pyruvate are oxidized to 2 acetyl CoA and 2 NADH.2 NADH enter electron transport to provide 6 ATP.Summary:2 Pyruvate Acetyl CoA + 6 ATP
28 ATP from Citric Acid Cycle Reaction Pathway ATP (One Glucose)ATP from Citric Acid Cycle (2 acetyl-CoA)Oxidation of 2 isocitrate (2NADH) 6 ATPOxidation of 2 -ketoglutarate (2NADH) 6 ATP2 Direct substrate phosphorylations (2GTP) 2 ATPOxidation of 2 succinate (2FADH2) 4 ATPOxidation of 2 malate (2NADH) 6 ATP24 ATPSummary: 2Acetyl CoA + 24 ADP + 24 Pi4CO2 + 2H2O + 24 ATP + 2 CoASH
29 ATP from Glucose From glycolysis 6 – 8 ATP From 2 pyruvate 6 ATP One glucose molecule undergoing complete oxidation provides:From glycolysis – 8 ATPFrom 2 pyruvate ATPFrom 2 acetyl CoA ATP36-38 ATPOverall ATP Production for one glucoseC6H12O6 + 6O2 + (36 – 38)ADP + (36 – 38) Piglucose CO2 + 6H2O + (36 – 38) ATP
30 ATP Energy from Glucose The complete oxidation of glucose yields6 CO26 H2O36-38 ATP