1. Fate of Pyruvate & Citric Acid Cycle
Introduction of Glucose Metabolism Lecture-3
Fate of Pyruvate & Citric Acid Cycle

2. Fate of pyruvate
1- Lactate (in cytosol) Enzyme: lactate dehyrogenase (LDH) in anaerobic glycolysis 2- Acetyl CoA in mitochondria Enzyme: pyruvate dehydrogenase occurs in aerobic glycolysis Acetyl CoA is required for citric acid cycle (CAC) 3- Oxalacetate Enzyme: pyruvate carboxylase Oxalacetate is required for: 1- Citric acid cycle (condenses with acetyl CoA): to yield energy ATP OR 2-Gluconeogenesis (to synthesize glucose)

3. Fate of Pyruvate Glucose ACETYL CoA glycolysis Gluconeogenesis
No Oxygen
No Mitochondria
OR BOTH
mitochondria
PYRUVATE
LACTATE
OXALACETATE
Oxygen
&
Mitochondria
ACETYL CoA
CITRIC ACID CYCLE

4. LACTATE DEHYDROGENASE

5. FATES OF PYRUVATE 5

6. OXIDATIVE DECARBOXYLATION OF PYRUVATE
Allosteric
Regulation 6

7. Formation of acetyl CoA from pyruvate
Pyruvate (end product of aerobic glycolysis) is transported into the mitochondria.
In the mitochondrial matrix, pyruvate is converted to acetyl CoA by
pyruvate dehydrogenase complex (multienzyme complex)
This reaction is irreversible
Pyruvate dehydrogenase complex is composed of three enzymes & five coenzymes
Coenzymes of the complex are derived from water soluble vitamins:
1- Thiamine pyruphosphate, TPP (derived from thiamine, vitamin B1)
2- NAD+ (derived from niacin)
3- FAD (derived from riboflavin)
4- Lipoic acid
5- Coenzyme A (derived from pantothenic acid)

8. Pyruvate dehydrogenase complex
ACETYL CoA

9. Citric acid cycle or,(Krebs cycle)

10. Citric Acid Cycle
Citric acid cycle is the final pathway where the oxidative metabolism of Carbohydrates (as glucose), proteins (amino acids) & lipids (fatty acids) to yield energy (ATP)
Acetyl CoA is the end product for oxidation of carbohydrates, lipids & proteins
Acetyl CoA condenses with oxalacetate to form citrate (first reaction of the cycle)
3 NADH are produced = 3 X 3 = 9 ATP (by oxidative phosphorylation)
One FADH2 is produced = 1 X 2 = 2 ATP (by oxidative phosphorylation)
One ATP is produced (by substrate level phosphorylation)
Net = 12 ATP / one acetyl CoA

11. Citric Acid Cycle CYCLE - SUMMARY
Acetyl CoA
3 NAD
3 NADH + H
2 CO2
1 FAD
1 FADH2
1 ADP
1 ATP

13. KREBS CYCLE REACTIONS (1)
هذا الريآكشن موش مهم موش لازم تعرفو خالص
المهم أن تعرف إنه طلع 6 إي تي بي يعني 3 3 13

14. KREBS CYCLE REACTIONS (2)
Succinate Thiokinase
# سموا كذلك لأنهم لا يستخدمون الريسبايراتوري تشين
Substrate-Level
Phosphorylation 14

15. KREBS CYCLE REACTIONS (3)

16. KREBS CYCLE: ENERGY YIELD

17. Citric acid cycle or,(Krebs cycle)