The Krebs Cycle: Citric Acid Cycle & Cellular Energy
The Krebs Cycle: Citric Acid Cycle & Cellular Energy
Biochemistry
A rigorous, university-level study of the citric acid cycle (Krebs cycle / TCA cycle) — the central metabolic hub that oxidizes acetyl-CoA to CO2, generates reduced electron carriers (NADH and FADH2) for oxidative phosphorylation, and provides biosynthetic precursors for amino acids, lipids, and nucleotides.
Learning Objectives
- Describe the pyruvate dehydrogenase complex and the generation of acetyl-CoA
- Identify each of the eight reactions of the citric acid cycle, including enzymes, substrates, and products
- Calculate the per-turn and per-glucose yield of NADH, FADH2, GTP, and CO2
- Explain allosteric and covalent regulation of the cycle at the levels of PDC, citrate synthase, isocitrate dehydrogenase, and alpha-ketoglutarate dehydrogenase
- Discuss anaplerotic and cataplerotic reactions that feed into and drain from the cycle
- Relate citric acid cycle defects to clinical conditions including thiamine deficiency, fumarase deficiency, and neurodegeneration
- Connect the cycle to the electron transport chain and oxidative phosphorylation
Lessons
1
Introduction: The Central Hub of Metabolism
12 min
2
Pyruvate Dehydrogenase Complex: The Gateway Reaction
12 min
3
The Eight Reactions of the Krebs Cycle (Part 1: Steps 1–4)
14 min
4
The Eight Reactions of the Krebs Cycle (Part 2: Steps 5–8)
12 min
5
Regulation of the Krebs Cycle
10 min
6
Anaplerotic & Cataplerotic Reactions
10 min
7
Connection to the Electron Transport Chain & Total ATP Yield
12 min
8
Clinical Significance & Integration
10 min