Krebs Cycle – Energy Factory of Cells
(also known as the Citric Acid Cycle or TCA Cycle)
Location: Happens inside mitochondria
Main Purpose: To produce energy by breaking down Acetyl-CoA
Steps (Simplified)
1. Acetyl-CoA + Oxaloacetate → Citrate
2. Citrate → Isomerized to Isocitrate
3. Isocitrate → α-Ketoglutarate + CO₂ + NADH
4. α-Ketoglutarate → Succinyl-CoA + CO₂ + NADH
5. Succinyl-CoA → Succinate + ATP
6. Succinate → Fumarate + FADH₂
7. Fumarate → Malate
8. Malate → Oxaloacetate + NADH (cycle restarts)
Key Outputs (per cycle)
✅ 3 NADH
✅ 1 FADH₂
✅ 1 ATP (or GTP)
✅ 2 CO₂ Fact:
Krebs Cycle itself makes only a small amount of ATP, but it's essential for producing
NADH and FADH₂, which power the cell’s energy system.
(also known as the Citric Acid Cycle or TCA Cycle)
Location: Happens inside mitochondria
Main Purpose: To produce energy by breaking down Acetyl-CoA
Steps (Simplified)
1. Acetyl-CoA + Oxaloacetate → Citrate
2. Citrate → Isomerized to Isocitrate
3. Isocitrate → α-Ketoglutarate + CO₂ + NADH
4. α-Ketoglutarate → Succinyl-CoA + CO₂ + NADH
5. Succinyl-CoA → Succinate + ATP
6. Succinate → Fumarate + FADH₂
7. Fumarate → Malate
8. Malate → Oxaloacetate + NADH (cycle restarts)
Key Outputs (per cycle)
✅ 3 NADH
✅ 1 FADH₂
✅ 1 ATP (or GTP)
✅ 2 CO₂ Fact:
Krebs Cycle itself makes only a small amount of ATP, but it's essential for producing
NADH and FADH₂, which power the cell’s energy system.
