Curriculum
Module 03 · 70 min
Glycolysis & the TCA Cycle
The two engines of central carbon metabolism — and why both matter at the bedside.
CoreClinicalResearch
Topics
What this module covers
- 01Energy investment and payoff phases of glycolysis
- 02Pyruvate dehydrogenase as the gateway to mitochondria
- 03TCA cycle: anaplerosis, cataplerosis, cycle as crossroads
- 04Warburg effect and clinical PET imaging
Deep-dive lessons
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Learning objectives
By the end of this module you will be able to
- L01Walk through the 10 enzymatic steps of glycolysis from glucose to pyruvate.
- L02Explain how the TCA cycle generates reducing equivalents for the ETC.
- L03Connect the Warburg effect to FDG-PET findings in oncology.
Expected takeaways
What you should walk away believing
- →Hexokinase, PFK-1, and pyruvate kinase are the regulated steps.
- →The TCA cycle is amphibolic — both catabolic and biosynthetic.
- →Tumor cells often upregulate glycolysis even with oxygen present (Warburg).
Core summary
At the Core level
Glycolysis breaks one glucose into two pyruvate, generating a net 2 ATP and 2 NADH in the cytoplasm. Pyruvate then enters mitochondria to feed the TCA cycle, which extracts most of the cell's energy as electron carriers.
Myth vs reality
Common misconception
Claim
Cancer cells use glycolysis because they lack mitochondria.
Reality
Most tumors retain functional mitochondria; the Warburg shift is a regulatory choice driven by oncogenic signaling and biosynthetic demand.
Evidence-graded claims
Claims, scored A–F
A
Glycolysis nets 2 ATP per glucose
Standard biochemistry.
A
PET-FDG uptake correlates with glycolytic rate in many tumors
Routine clinical use.
F
Lactate is a 'waste product'
Lactate is a major inter-organ fuel and signaling molecule.
Quiz
Check your understanding
Q1. Net ATP from glycolysis per glucose?
Q2. Rate-limiting step of glycolysis?
Q3. Warburg effect refers to…
Flashcards
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Front
Three regulated enzymes of glycolysis?
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Pathway Atlas
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Suggested reading
Primary literature
- Understanding the Warburg effect: the metabolic requirements of cell proliferation — Vander Heiden et al., Science 2009 ↗