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Stages of Metabolism.

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Presentation on theme: "Stages of Metabolism."— Presentation transcript:

1 Stages of Metabolism

2 Pyruvate Oxidation Conversion to acetyl–CoA
Catalyzed by pyruvate dehydrogenase Decarboxylation - 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.

5 Citric Acid Cycle Entry from Acetyl–CoA

6 Citric Acid Cycle Citrate to Isocitrate

7 Citric Acid Cycle First Oxidation
Key point: requires NAD+

8 Citric Acid Cycle Second Oxidation
Key point: requires NAD+

9 Citric Acid Cycle Substrate-Level Phosphorylation

10 Citric Acid Cycle Third Oxidation

11 Citric Acid Cycle Hydration

12 Citric Acid Cycle Fourth Oxidation
Key point: requires NAD+

13 An acetyl group bonds with oxaloacetate to form citrate
Two decarboxylations remove two carbons as 2CO2 Four 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 + 2H2O 2CO2 + 3NADH + 3H+ + FADH2 + HS-CoA + GTP One turn of the citric acid cycle produces: 2 CO GTP (1ATP) 3 NADH HS-COA 1 FADH2

15 Citric Acid Cycle Conversion of 3 alcohol into 2 alcohol: Now
able to be oxidized o

16 Regulation of Citric Acid Cycle
The reaction rate for the citric acid cycle Increases when high levels of ADP or NAD+ activate isocitrate dehydrogenase and -ketoglutarate dehydrogenase Decreases when high levels of ATP or NADH inhibit isocitrate dehydrogenase. Decreases when high levels of NADH or succinyl–CoA inhibit -ketoglutarate dehydrogenase. Formation of acetyl–CoA from pyruvate (catalyzed by pyruvate dehydrogenase) also activated by ADP and inhibited by ATP and NADH.

17 Mitochondrial Structure

18 FMN (Flavin mononucleotide)
FMN coenzyme Contains 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
Cyt c1 2 NADH + 2 H+ + O NAD H2O 2 FADH2 + O FAD H2O

22 Chemiosmotic Model of Electron Transport
During electron flow Complexes I, III, and IV pump protons into the intermembrane space creating a proton gradient. Protons pass through ATP synthase to return to the matrix. The flow of protons through ATP synthase provides the energy for 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) provides sufficient energy for 3ATPs NADH + 3ADP + 3Pi NAD ATP From FADH2 (Complex II) provides sufficient energy for 2ATPs FADH ADP + 3Pi FAD + 2ATP

25 Regulation of Electron Transport
The electron transport system is regulated by High levels of ADP and NADH that activate electron transport. Low levels of ADP, Pi, oxygen, and NADH that decrease electron transport activity.

26 ATP from Glycolysis Reaction Pathway ATP for One Glucose
Activation of glucose ATP Oxidation of 2 NADH (as FADH2) 4 ATP Direct ADP phosphorylation (two triose) 4 ATP 6 ATP Summary: C6H12O pyruvate + 2H2O + 6 ATP glucose

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 ATP Oxidation of 2 -ketoglutarate (2NADH) 6 ATP 2 Direct substrate phosphorylations (2GTP) 2 ATP Oxidation of 2 succinate (2FADH2) 4 ATP Oxidation of 2 malate (2NADH) 6 ATP 24 ATP Summary: 2Acetyl CoA + 24 ADP + 24 Pi 4CO2 + 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 ATP From 2 pyruvate ATP From 2 acetyl CoA ATP 36-38 ATP Overall ATP Production for one glucose C6H12O6 + 6O2 + (36 – 38)ADP + (36 – 38) Pi glucose CO2 + 6H2O + (36 – 38) ATP

30 ATP Energy from Glucose
The complete oxidation of glucose yields 6 CO2 6 H2O 36-38 ATP

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