Chapter 14, Problem 1P

Summary Introduction

To determine: The balanced biochemical equations for all the reactions in the catabolism of glucose to two molecules of glyceraldehyde 3-phosphate, including the standard free energy change for each reaction.

Introduction:

Two molecules of ATP are required during the preparatory phase of glycolysis and the hexose chain is splitted into two triose phosphates.

Explanation of Solution

The balanced biochemical equations for all the reactions in glucose catabolism to two molecules of glyceraldehyde 3-phosphate is given as:

$\begin{array}{l}\text{Glucose}+\text{ATP}\underset{\text{hexokinase}}{\overset{{\text{Mg}}^{\text{2+}}}{\to }}\text{Glucose-6-phosphate}+\text{ADP}\text{Δ}{G}^{\text{o}}=-\text{16}\text{.7}\text{kJ/mol}\\ \text{Glucose-6-phosphate}\underset{\begin{array}{l}\text{phosphohexose}\\ \text{isomerase}\end{array}}{\overset{{\text{Mg}}^{\text{2+}}}{\rightleftharpoons }}\left(\begin{array}{l}\text{Fructose-6-phosphate}\\ +\text{ADP}\end{array}\right)\text{Δ}{G}^{\text{o}}=1.\text{7}\text{kJ/mol}\\ \left(\begin{array}{l}\text{Fructose-6-phosphate}\\ +\text{ATP}\end{array}\right)\underset{\text{phosphofructokinase-1}}{\overset{{\text{Mg}}^{\text{2+}}}{\to }}\left(\begin{array}{l}\text{Fructose-1,6-biphosphate}\\ +\text{ADP}\end{array}\right)\text{Δ}{G}^{\text{o}}=-14.\text{2}\text{kJ/mol}\end{array}$

$\begin{array}{l}\text{Fructose-1,6-biphosphate}\underset{\text{aldolase}}{\rightleftharpoons }\left(\begin{array}{l}\text{Dihydroxyacetonephosphate}+\\ \text{Glyceraldehyde-3-phosphate}\end{array}\right)\text{Δ}{G}^{\text{o}}=23.8\text{kJ/mol}\\ \text{Dihydroxyacetonephosphate}\underset{\begin{array}{l}\text{triose}\text{phosphate}\\ \text{isomerase}\end{array}}{\rightleftharpoons }\text{Glyceraldehyde-3-phosphate}\text{Δ}{G}^{\text{o}}=7.5\text{kJ/mol}\end{array}$

Conclusion

Glycolysis is a series of reactions catalyzed by enzymes which produces two molecules of pyruvate along with the free energy which is conserved in the form of NADH and ATP. The reactions in glucose catabolism are depicted above.

Summary Introduction

To determine: The overall or net equation for the preparatory phase of glycolysis, with the net standard free-energy change.

Introduction:

Glycolysis is a series of enzyme catalyzed reactions that yield two molecules of the three carbon compound pyruvate along with the free energy which is conserved in the form of NADH and ATP.

Explanation of Solution

The overall equation for the preparatory phase of glycolysis, with the net standard free-energy change includes:

$\text{Glucose}+\text{2ATP}\to \text{Glyceraldehyde-3-phosphate}+\text{2ADP}+{\text{2H}}^{\text{+}}{\text{ΔG}}^{\text{o}}=\text{2}\text{.1}\text{kJ/mol}$

Conclusion

Glycolysis is a series of reactions catalyzed by enzymes which produces two molecules of pyruvate along with the free energy which is preserved in the form of NADH and ATP. The equation for the preparatory phase of glycolysis is depicted above.