Which of the following is the correct sequence of glycolysis ?

Options

A. `G 6 P rarr PEP rarr 3rarr PGAL rarr 3 rarr PGA `
B. `G 6 - P rarr 3 - PGAL rarr 3 - PGA rarr PEP`
C. `G 6 -P rarr PEP rarr 3 - PGA rarr 3-PGAL`
D. `G6-P rarr 3-PGA rarr 3-PGAL rarr PEP`

Answer

To determine the correct sequence of glycolysis, we need to follow the steps involved in the glycolytic pathway. Here’s a step-by-step breakdown of the glycolysis process:

### Step-by-Step Solution:

1. **Glucose Conversion**:
- Glycolysis begins with the conversion of glucose into glucose-6-phosphate (G6P). This step requires the investment of one ATP molecule.

2. **Isomerization**:
- Glucose-6-phosphate is then converted into fructose-6-phosphate (F6P) through an isomerization reaction.

3. **Phosphorylation**:
- Fructose-6-phosphate is phosphorylated to form fructose-1,6-bisphosphate (F1,6BP). This step also uses one ATP molecule.

4. **Cleavage**:
- Fructose-1,6-bisphosphate is split into two three-carbon molecules: dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (G3P or PGAL).

5. **Interconversion**:
- Dihydroxyacetone phosphate can be converted into glyceraldehyde-3-phosphate, so we focus on glyceraldehyde-3-phosphate for the next steps.

6. **Oxidation and Phosphorylation**:
- Glyceraldehyde-3-phosphate is oxidized and phosphorylated to form 1,3-bisphosphoglycerate (1,3-BPG). This step produces NADH.

7. **ATP Generation**:
- 1,3-bisphosphoglycerate is converted to 3-phosphoglycerate (3-PGA), generating ATP through substrate-level phosphorylation.

8. **Conversion**:
- 3-phosphoglycerate is then converted into 2-phosphoglycerate (2-PGA).

9. **Dehydration**:
- 2-phosphoglycerate is dehydrated to form phosphoenolpyruvate (PEP).

10. **Final ATP Generation**:
- Phosphoenolpyruvate is converted into pyruvate, generating another ATP molecule through substrate-level phosphorylation.

### Summary of the Sequence:
The correct sequence of glycolysis can be summarized as follows:
1. Glucose
2. Glucose-6-phosphate (G6P)
3. Fructose-6-phosphate (F6P)
4. Fructose-1,6-bisphosphate (F1,6BP)
5. Dihydroxyacetone phosphate (DHAP) and Glyceraldehyde-3-phosphate (G3P)
6. 1,3-bisphosphoglycerate (1,3-BPG)
7. 3-phosphoglycerate (3-PGA)
8. 2-phosphoglycerate (2-PGA)
9. Phosphoenolpyruvate (PEP)
10. Pyruvate

### Final Answer:
The correct sequence of glycolysis is: **Glucose → Glucose-6-phosphate → Fructose-6-phosphate → Fructose-1,6-bisphosphate → Dihydroxyacetone phosphate and Glyceraldehyde-3-phosphate → 1,3-bisphosphoglycerate → 3-phosphoglycerate → 2-phosphoglycerate → Phosphoenolpyruvate → Pyruvate.**