Glycolysis process illustrating the conversion of glucose to pyruvate with energy production.

The image provided is a worksheet for the process of glycolysis, which is a metabolic pathway that breaks down glucose into pyruvate in the absence of oxygen. The goal is to fill in the enzymes and intermediates involved in each step of glycolysis. Below is the solution with explanations:

Glycolysis Pathway Overview

Glycolysis consists of 10 steps, divided into two phases:
1. Energy Investment Phase (Steps 1-3): Requires ATP to phosphorylate glucose.
2. Energy Payoff Phase (Steps 4-10): Produces ATP and NADH.

Step-by-Step Solution

#### Step 1: Phosphorylation of Glucose
- Enzyme: Hexokinase
- Reaction: Glucose + ATP → Glucose-6-phosphate (G6P) + ADP
- Intermediate: Glucose-6-phosphate (G6P)

#### Step 2: Isomerization to Fructose-6-phosphate
- Enzyme: Phosphoglucose isomerase
- Reaction: Glucose-6-phosphate → Fructose-6-phosphate (F6P)
- Intermediate: Fructose-6-phosphate (F6P)

#### Step 3: Phosphorylation of Fructose-6-phosphate
- Enzyme: Phosphofructokinase-1 (PFK-1)
- Reaction: Fructose-6-phosphate + ATP → Fructose-1,6-bisphosphate (F1,6BP) + ADP
- Intermediate: Fructose-1,6-bisphosphate (F1,6BP)

#### Step 4: Cleavage of Fructose-1,6-bisphosphate
- Enzyme: Aldolase
- Reaction: Fructose-1,6-bisphosphate → Glyceraldehyde-3-phosphate (G3P) + Dihydroxyacetone phosphate (DHAP)
- Intermediate: Glyceraldehyde-3-phosphate (G3P) and Dihydroxyacetone phosphate (DHAP)

#### Step 5: Conversion of DHAP to G3P
- Enzyme: Triose phosphate isomerase
- Reaction: Dihydroxyacetone phosphate (DHAP) → Glyceraldehyde-3-phosphate (G3P)
- Intermediate: Glyceraldehyde-3-phosphate (G3P)

#### Step 6: Oxidation of G3P
- Enzyme: Glyceraldehyde-3-phosphate dehydrogenase (GAPDH)
- Reaction: Glyceraldehyde-3-phosphate + Pi + NAD⁺ → 1,3-bisphosphoglycerate (1,3-BPG) + NADH + H⁺
- Intermediate: 1,3-bisphosphoglycerate (1,3-BPG)

#### Step 7: Formation of ATP
- Enzyme: Phosphoglycerate kinase
- Reaction: 1,3-bisphosphoglycerate + ADP → 3-phosphoglycerate (3-PG) + ATP
- Intermediate: 3-phosphoglycerate (3-PG)

#### Step 8: Rearrangement of 3-PG
- Enzyme: Phosphoglycerate mutase
- Reaction: 3-phosphoglycerate → 2-phosphoglycerate (2-PG)
- Intermediate: 2-phosphoglycerate (2-PG)

#### Step 9: Dehydration of 2-PG
- Enzyme: Enolase
- Reaction: 2-phosphoglycerate → Phosphoenolpyruvate (PEP)
- Intermediate: Phosphoenolpyruvate (PEP)

#### Step 10: Formation of Pyruvate
- Enzyme: Pyruvate kinase
- Reaction: Phosphoenolpyruvate + ADP → Pyruvate + ATP
- End Product: Pyruvate

Final Filled Worksheet

| Step | Enzyme | Intermediate / End Product |
|------|----------------------------|-----------------------------|
| 1 | Hexokinase | Glucose-6-phosphate (G6P) |
| 2 | Phosphoglucose isomerase | Fructose-6-phosphate (F6P) |
| 3 | Phosphofructokinase-1 (PFK-1) | Fructose-1,6-bisphosphate (F1,6BP) |
| 4 | Aldolase | Glyceraldehyde-3-phosphate (G3P), Dihydroxyacetone phosphate (DHAP) |
| 5 | Triose phosphate isomerase | Glyceraldehyde-3-phosphate (G3P) |
| 6 | Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) | 1,3-bisphosphoglycerate (1,3-BPG) |
| 7 | Phosphoglycerate kinase | 3-phosphoglycerate (3-PG) |
| 8 | Phosphoglycerate mutase | 2-phosphoglycerate (2-PG) |
| 9 | Enolase | Phosphoenolpyruvate (PEP) |
| 10 | Pyruvate kinase | Pyruvate |

Summary of Products

- Net ATP Produced: 2 ATP (4 ATP produced, but 2 ATP consumed in the energy investment phase).
- Net NADH Produced: 2 NADH.
- End Product: Pyruvate.

Explanation

Each step involves specific enzymes that catalyze the transformation of one intermediate to another. The key points are:
1. ATP Investment: Steps 1 and 3 consume ATP to phosphorylate glucose and fructose-6-phosphate.
2. ATP Production: Steps 7 and 10 produce ATP by substrate-level phosphorylation.
3. NADH Production: Step 6 oxidizes glyceraldehyde-3-phosphate, producing NADH.
4. Final Product: Pyruvate is the end product of glycolysis, which can be further metabolized in aerobic or anaerobic conditions.

Final Answer

\boxed{
\begin{array}{|c|c|c|}
\hline
\text{Step} & \text{Enzyme} & \text{Intermediate / End Product} \\
\hline
1 & \text{Hexokinase} & \text{Glucose-6-phosphate (G6P)} \\
\hline
2 & \text{Phosphoglucose isomerase} & \text{Fructose-6-phosphate (F6P)} \\
\hline
3 & \text{Phosphofructokinase-1 (PFK-1)} & \text{Fructose-1,6-bisphosphate (F1,6BP)} \\
\hline
4 & \text{Aldolase} & \text{Glyceraldehyde-3-phosphate (G3P), Dihydroxyacetone phosphate (DHAP)} \\
\hline
5 & \text{Triose phosphate isomerase} & \text{Glyceraldehyde-3-phosphate (G3P)} \\
\hline
6 & \text{Glyceraldehyde-3-phosphate dehydrogenase (GAPDH)} & \text{1,3-bisphosphoglycerate (1,3-BPG)} \\
\hline
7 & \text{Phosphoglycerate kinase} & \text{3-phosphoglycerate (3-PG)} \\
\hline
8 & \text{Phosphoglycerate mutase} & \text{2-phosphoglycerate (2-PG)} \\
\hline
9 & \text{Enolase} & \text{Phosphoenolpyruvate (PEP)} \\
\hline
10 & \text{Pyruvate kinase} & \text{Pyruvate} \\
\hline
\end{array}
}