Glycolysis Flashcards
1st Step in Glycolysis
Glucose —> Glucose-6-phosphate
- Enzyme: Hexokinase
- Uses ATP —> ADP
Additional Info:
- Irreversible step, so G6P gets stuck inside the cell
- Since ATP is required, AMP/ADP are required to activate hexokinase
- Hexokinase is replaced by glucokinase in liver and pancreatic β-islet cells
2nd Step in Glycolysis
Glucose-6-Phosphate —> Fructose-6-Phosphate
- Enzyme: Phosphoglucose Isomerase
Additional Info:
- Reversible step
3rd Step in Glycolysis
Fructose-6-Phosphate —> Fructose-1,6-Bisphosphate
- Enzyme: Phosphofructokinase-1
- ATP —> ADP
Additional Info:
- RATE LIMITING STEP (slowest step)
- Irreversible step
- AMP/ADP and Fructose-2,6-Bisphosphate activate
- ATP and citrate inhibit
4th Step in Glycolysis
Fructose-1,6-Bisphosphate —> Dihydroxyacetone Phosphate (DHAP) + Glyceraldehyde-3-Phosphate
- Enzyme: Aldolase
Additional Info:
- Reversible step
- Only Glyceraldehyde-3-Phosphate can continue in the cycle
5th Step in Glycolysis
Dihydroxyacetone Phosphate (DHAP) —> Glyceraldehyde-3-Phosphate
- Enzyme: Triosephosphate Isomerase
Additional Info:
- Reversible step
- In tandem with step 4, produces 2 Glyceraldehyde-3-Phosphate molecules
6th Step in Glycolysis
2 Glyceraldehyde-3-Phosphate —> 2 1,3-Bisphosphoglycerate
- Enzyme: Glyceraldehyde-3-Phosphate Dehydrogenase
- 2 NAD+ + 2 Pi —> 2 NADH + 2 H+
Additional Info:
- The first half-reaction is oxidation of Glyceraldehyde-3-Phosphate
- The second half-reaction is reduction of NAD+
- The reaction is exergonic, which allows the Pi to phosphorylate Glyceraldehyde-3-Phosphate
- Reversible step
7th Step in Glycolysis
2 1,3-Bisphosphoglycerate —> 2 3-Phosphoglycerate
- Enzyme: Phosphoglycerate Kinase
- 2 ADP —> 2 ATP
Additional Info:
- 1,3-Bisphosphoglycerate donates a phosphate group to ADP
- Irreversible step
8th Step in Glycolysis
2 3-Phosphoglycerate —> 2 2-Phosphoglycerate
- Enzyme: Phosphoglyceromutase
Additional Info:
- Reversible step
- Converts between isomers
9th Step in Glycolysis
2 2-Phosphoglycerate —> 2 Phosphoenolpyruvate (PEP)
- Enzyme: Enolase
- Loses 2 H2O
Additional Info:
- Phosphoenolpyruvate is an unstable molecule ready to lose its final phosphate group
- Reversible step
10th Step in Glycolysis
2 Phosphoenolpyruvate —> 2 Pyruvate
- Enzyme: Pyruvate Kinase
- 2 ADP —> 2 ATP
Additional Info:
- Irreversible step
- Phosphoenolpyruvate donates its phosphate to ADP
Phases of Glycolysis
Phase 1: Energy-Requiring Phase
Phase 2: Energy-Releasing Phase
Products of Energy-Requiring Phase
2 Glyceraldehyde-3-Phosphate
-2 ATP
Products of Energy-Releasing Phase
4 ATP
2 NADH
2 Pyruvate
Products of Full Glycolysis
2 ATP
2 NADH
2 Pyruvate
