Cue Column | Notes Column
| Cue / Question | Notes |
|---|---|
| What is glycolysis? | 10-step enzymatic conversion of glucose (6C) → 2 pyruvate (3C); occurs in cytoplasm; common to aerobic and anaerobic; no needed |
| Investment vs Payoff? | Investment phase: 2 ATP consumed (hexokinase + PFK). Payoff phase: 4 ATP produced. Net = 2 ATP + 2 NADH |
| Rate-limiting enzyme? | Phosphofructokinase (PFK) — step 3; allosteric enzyme; inhibited by high ATP and citrate; activated by AMP/ADP |
| Three key enzymes? | 1. Hexokinase (step 1: glucose → G6P); 2. PFK (step 3: F6P → F1,6BP — rate-limiting); 3. Pyruvate kinase (step 10: PEP → pyruvate, substrate-level phosphorylation) |
| What is substrate-level phosphorylation? | Direct transfer of phosphate from substrate to ADP (no ETS needed); occurs at steps 7 and 10 of glycolysis |
| End products? | 2 pyruvate + 2 ATP (net) + 2 NADH per glucose |
Summary
Glycolysis is the universal pathway of glucose catabolism, occurring in all living cells. Its rate is controlled by PFK, which acts as a metabolic throttle responding to the cell's energy status. The 2 NADH produced feed into the ETS (aerobic) or are reoxidised during fermentation (anaerobic) to regenerate N.