Question

Formation of phosphoenolpyruvate from 2-pliosphoglycerate is
A. Dehydration
B. Dehydrogenation
C. Oxidation
D. Hydration

Answer 1

Hint: Glycolysis is a metabolic pathway that involves catabolism (breakdown) of six glucose molecules into two molecules of Pyruvate. It is a $10$ step pathway. It is a biological process that takes place in the cytosol. It is an aerobic pathway and involves the lysis of glucose for energy production.

Complete answer:
We know that Glycolysis is a process where the breakdown of six glucose molecules occurs in order to form two molecules of pyruvate. It is a ten step pathway and occurs in the cytosol.
The first five steps involve the Preparatory phase/energy investment phase as in these steps the energy is invested. The ATP is utilized in these steps.

The first five steps include the following conversions-
- $\text{Glucose} \to \text{Glucose} - 6 - \text{phosphate}\;(ATP \to ADP)$
- $\text{Glucose} - 6 - \text{phosphate} \to \text{Fructose} - 6 - \text{phosphate}$
- $\text{Fructose} - 6 - \text{phosphate} \to \text{Fructose} - 1,6 - \text{bisphosphate}\;(ATP \to ADP)$
- $\text{Fructose} - 1,6 - \text{bisphosphate} \to \text{Glyceraldehyde} - 3 - \text{phosphate }+ \text{Dihydroxyacetone phosphate}$

The next five steps include the Pay off phase/Energy generation phase and include the following conversions-
- $\text{Dihydroxyacetone phosphate} \to \text{Glyceraldehyde} - 3 - \text{phosphate}$
- $\text{Glyceraldehyde} - 3 - \text{phosphate} \to 1,3 - \text{bisphosphoglycerate}\;(NA{D^ + } \to NADH)$
- $1,3 - \text{bisphosphoglycerate} \to 3 - \text{phosphoglycerate}\;(ADP \to ATP)$
- $3 - \text{phosphoglycerate} \to 2 - \text{phosphoglycerate}$
- $2 - \text{phosphoglycerate} \to \text{Phosphoenolpyruvate},\;2\;{H_2}O \uparrow $
- $\text{phosphoenol pyruvate} \to \text{Pyruvate} \;(2ADP \to 2ATP)$

The above steps clearly indicate the formation of Pyruvate from Glucose. So, we can say that the formation of phosphoenolpyruvate from 2-pliosphoglycerate involves dehydration as there is the removal of $2$ molecules of water.

Hence, the correct answer is option (A).

Additional information:
• Dehydration- It involves the loss of water.
• Dehydrogenation- It involves the removal of hydrogen and not of the whole water molecule.
• Oxidation- It involves the loss of electrons.
• Hydration- It involves the addition of water.

Note: Glycolysis is an aerobic pathway. The major steps include-
Glucose always produces two molecules of pyruvic acids.
Initially ATP is required and then ATP is produced.
So, a total of six ATP are produced during aerobic reaction.