Glycolysis practice sheet illustrating the biochemical pathway of glucose breakdown into pyruvate, including energy input and output.

Let's solve this Glycolysis Practice Sheet step by step.

This diagram represents the pathway of glycolysis, the metabolic process that breaks down one molecule of glucose into two molecules of pyruvate, producing ATP and NADH in the process.

We'll fill in each blank based on the known steps of glycolysis. The pathway is divided into 10 steps, but here it's simplified into key stages with intermediates.

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Step-by-step breakdown:

#### Step 1: Glucose → Glucose-6-phosphate
- Enzyme: Hexokinase
- Input: Glucose + ATP (with Mg²⁺)
- Output: Glucose-6-phosphate + ADP

✔ Fill in:
- Top box: Glucose
- Below: Glucose-6-phosphate

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#### Step 2: Glucose-6-phosphate → Fructose-6-phosphate
- Enzyme: Phosphoglucose isomerase
- No ATP involved.

✔ Fill in:
- Next box: Fructose-6-phosphate

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#### Step 3: Fructose-6-phosphate → Fructose-1,6-bisphosphate
- Enzyme: Phosphofructokinase-1 (PFK-1)
- Input: ATP + Mg²⁺
- Output: ADP

✔ Fill in:
- Box below: Fructose-1,6-bisphosphate

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#### Step 4: Fructose-1,6-bisphosphate → Dihydroxyacetone phosphate (DHAP) + Glyceraldehyde-3-phosphate (G3P)
- Enzyme: Fructose bisphosphate aldolase
- This step splits the 6-carbon molecule into two 3-carbon molecules.
- One molecule of G3P and one of DHAP are produced.
- DHAP is quickly converted to G3P.

✔ Fill in:
- Left box: Dihydroxyacetone phosphate (DHAP)
- Right box: Glyceraldehyde-3-phosphate (G3P)

But since DHAP → G3P via triose phosphate isomerase, we end up with 2 molecules of G3P.

So, the next step uses 2 x G3P.

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#### Step 5: Glyceraldehyde-3-phosphate → 1,3-Bisphosphoglycerate
- Enzyme: Glyceraldehyde-3-phosphate dehydrogenase**
- Inputs: G3P + Pi + NAD⁺
- Outputs: 1,3-BPG + NADH + H⁺

✔ Fill in:
- Below "2 x" → 1,3-Bisphosphoglycerate
- Arrow from NAD⁺ → NADH + H⁺

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#### Step 6: 1,3-Bisphosphoglycerate → 3-Phosphoglycerate
- Enzyme: Phosphoglycerate kinase**
- Uses: ADP → ATP (substrate-level phosphorylation)

✔ Fill in:
- Below: 3-Phosphoglycerate
- Note: 2 x ATP produced here (from 2 x 1,3-BPG)

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#### Step 7: 3-Phosphoglycerate → 2-Phosphoglycerate
- Enzyme: Phosphoglycerate mutase**
- No energy change.

✔ Fill in:
- Below: 2-Phosphoglycerate

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#### Step 8: 2-Phosphoglycerate → Phosphoenolpyruvate (PEP)
- Enzyme: Enolase**
- Requires Mg²⁺ and H₂O

✔ Fill in:
- Below: Phosphoenolpyruvate (PEP)

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#### Step 9: Phosphoenolpyruvate → Pyruvate
- Enzyme: Pyruvate kinase**
- Uses: ADP → ATP (another substrate-level phosphorylation)

✔ Fill in:
- Final box: Pyruvate
- Also, 2 x ATP produced here

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✔ Final Completed Diagram:

```
Glycolysis practice sheet

[Glucose]
↓ (ATP → ADP, Mg²⁺)
[Glucose-6-phosphate]
↓
[Fructose-6-phosphate]
↓ (ATP → ADP, Mg²⁺)
[Fructose-1,6-bisphosphate]
↓
[Dihydroxyacetone phosphate] + [Glyceraldehyde-3-phosphate]
↑ ↑
| |
| (converts to G3P) |
↓ ↓
2 x [Glyceraldehyde-3-phosphate]
↓ (Pi + NAD⁺ → NADH + H⁺)
2 x [1,3-Bisphosphoglycerate]
↓ (ADP → ATP, Mg²⁺)
2 x [3-Phosphoglycerate]
↓
2 x [2-Phosphoglycerate]
↓ (H₂O, Mg²⁺)
2 x [Phosphoenolpyruvate]
↓ (ADP → ATP, Mg²⁺)
2 x [Pyruvate]
```

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🔍 Summary of Key Points:

- Net ATP gain: 4 ATP produced – 2 ATP used = 2 ATP net
- NADH produced: 2 NADH (from 2 G3P molecules)
- Final products per glucose: 2 Pyruvate, 2 ATP, 2 NADH

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✔ Answered All Blanks:

Fill in the boxes in order:

1. Glucose
2. Glucose-6-phosphate
3. Fructose-6-phosphate
4. Fructose-1,6-bisphosphate
5. Dihydroxyacetone phosphate
6. Glyceraldehyde-3-phosphate
7. 1,3-Bisphosphoglycerate
8. 3-Phosphoglycerate
9. 2-Phosphoglycerate
10. Phosphoenolpyruvate
11. Pyruvate

And note the "2 x" applies to all steps after the split.

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Let me know if you'd like this as a printable version or need help labeling enzymes!