Can you complete the ten reactions of glycolysis by recognizing the chemical structures of their products? Start with glucose and follow the arrows to pyruvate. At each step, choose one of three structure-and-name cards.
Glycolysis at a Glance
Glycolysis is a ten-reaction pathway in the cytosol that converts one glucose molecule into two pyruvate molecules. It consumes two ATP during the investment phase and produces four ATP during the payoff phase, for a net gain of two ATP and two NADH per glucose.
The aldolase reaction splits a six-carbon sugar into glyceraldehyde-3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP). Triose phosphate isomerase converts DHAP into GAP; the later reactions therefore occur twice per glucose.
Interactive Glycolysis Pathway Quiz: All 10 Steps
Select the correct product for every enzyme-catalyzed reaction. Each choice includes the metabolite name and chemical structure. All ten reaction cards remain visible in a vertical pathway so you can follow the reaction sequence. Press Check answers to view your score and explanations; try again to review mistakes.
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Ten Enzymes of Glycolysis
| Step | Enzyme | Main change |
|---|---|---|
| 1 | Hexokinase | Glucose phosphorylation; ATP consumed |
| 2 | Phosphoglucose isomerase | Aldose–ketose rearrangement |
| 3 | Phosphofructokinase-1 | Second phosphorylation; ATP consumed |
| 4 | Aldolase | Cleavage into GAP and DHAP |
| 5 | Triose phosphate isomerase | Conversion of DHAP into GAP |
| 6 | GAP dehydrogenase | Oxidation; NADH produced |
| 7 | Phosphoglycerate kinase | ATP produced |
| 8 | Phosphoglycerate mutase | Phosphate position rearranged |
| 9 | Enolase | Water removed; PEP formed |
| 10 | Pyruvate kinase | ATP and pyruvate produced |
Why Learning Structures Helps
Structure recognition makes glycolysis easier to understand. Compare glucose-6-phosphate with fructose-6-phosphate, locate the added phosphate on fructose-1,6-bisphosphate, and distinguish the phosphate positions in 3-phosphoglycerate and 2-phosphoglycerate. The chemical transformation at each arrow is more informative than memorizing names alone.
Frequently Asked Questions
How many steps are in glycolysis?
Glycolysis consists of ten enzyme-catalyzed reactions from glucose to pyruvate.
What is the net ATP yield?
Two ATP molecules are consumed and four are formed per glucose, giving a net yield of two ATP.
Why are there two pyruvate molecules?
After the six-carbon intermediate is split into two three-carbon molecules, both three-carbon units pass through the payoff phase and ultimately produce two pyruvate molecules.
Related Study Guides
Read Has Glycolysis Changed in 50 Years? for a historical comparison. Explore more structure-recognition practice in our Carbohydrate Structure Quiz.
References
Nelson DL, Cox MM. Lehninger Principles of Biochemistry. 8th ed. W. H. Freeman; 2021.