Chapter 22, Problem 1P

Interpretation Introduction

Interpretation: Explain gluconeogenesis with the equation and the role of each component.

Concept Introduction: Mainly, pyruvate is converted into glucose in the gluconeogenesis pathway.

Answer to Problem 1P

Glucose is produced by pyruvate and the reduction of NADH. Pyruvate is further converted to phosphoenolpyruvate utilizing high energy phosphate bonds of ATP.

Explanation of Solution

The main reactions are as follows:

  $\begin{array}{l}\text{2 Pyruvate }+\text{ 4 ATP }+\text{ 2 GTP }+\text{ 2 NADH }+{\text{ 2 H}}^{+}+{\text{ 6 H}}_{\text{2}}\text{O}\stackrel{}{\to }\\ \text{ glucose }+\text{ 4 ADP }+\text{ 2 GDP }+\text{ 6 Pi }+{\text{ 2 NAD}}^{+}\\ \text{2 Pyruvate }+{\text{ 2 H}}^{+}+{\text{ 2 H}}_{\text{2}}\text{O }\stackrel{}{\to }\text{glucose }+{\text{ O}}_{\text{2}}\\ \text{2 NADH }+{\text{ 2 H}}^{+}+{\text{ O}}_{\text{2}}\stackrel{}{\to }{\text{2 NAD}}^{+}+{\text{ 2 H}}_{\text{2}}\text{O}\\ \text{4 ATP }+{\text{ 4 H}}_{\text{2}}\text{O} \stackrel{}{\to } \text{4ADP }+\text{ 4 Pi}\\ \text{2 ATP }+{\text{ 2 H}}_{\text{2}}\text{O} \stackrel{}{\to }\text{2 ADP }+\text{ 2 Pi}\end{array}$

The 2 GTP molecules are consumed by PEP carboxykinase and result PEP and 2 GDP.

Water is consumed during the hydrolysis of ATP and GTP.

A combination of two of 3-carbon pyruvate produces 6-carbon glucose. The keto carbon of pyruvate is oxidized when NADH is reduced to form glucose. Pyruvate is converted to phosphoenolpyruvate using the energy of hydrolyzed high-energy nucleoside triphosphates.