Chapter 13, Problem 13.9EP

(a)

Interpretation Introduction

Interpretation: To indicate whether the intermediate $\text{fructose 6}-\text{phosphate}$ in the glycolysis pathway is a ${\text{C}}_6$ molecule or a ${\text{C}}_3$ molecule.

Concept introduction: Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

The block diagram to represent an overview of glycolysis is as follows:

From the above diagram, it is concluded that in the overall process of glycolysis, two stages are present.

a) Steps 1 to 3 represents a six-carbon stage $\left({\text{C}}_6\text{ stage}\right)$.

b) Steps 4 to 10 represent a three-carbon stage $\left({\text{C}}_3\text{ stage}\right)$.

In the ${\text{C}}_6$ stage, the intermediates are derivatives of either glucose or fructose. Glucose and fructose contain six carbon atoms. Therefore, they are ${\text{C}}_6$ molecules. The phosphate groups are present in the intermediates.

In the ${\text{C}}_3$ stage, the intermediates are phosphorylated derivatives of glyceraldehyde, pyruvate, glycerate, or dihydroxyacetone, which are derivatives of either acetone or glycerol. Acetone and glycerol contain three carbon atoms. Therefore, they are ${\text{C}}_3$ molecules.

Answer to Problem 13.9EP

The intermediate $\text{fructose 6}-\text{phosphate}$ is a ${\text{C}}_6$ molecule.

Explanation of Solution

The structure of $\text{fructose 6}-\text{phosphate}$ is as follows:

Here,  denotes the ${\text{PO}}_3^{2-}$ unit.

The intermediate $\text{fructose 6}-\text{phosphate}$ is formed in the ${\text{C}}_6$ stage and it is the phosphorylated derivative of fructose. Therefore, the intermediate $\text{fructose 6}-\text{phosphate}$ is a ${\text{C}}_6$ molecule.

Conclusion

The intermediate $\text{fructose 6}-\text{phosphate}$ is formed in the ${\text{C}}_6$ stage and it is the phosphorylated derivative of fructose. It contains six carbon atoms. Therefore, it is a ${\text{C}}_6$ molecule.

(b)

Interpretation Introduction

Interpretation: To indicate whether the intermediate phosphoenolpyruvate in the glycolysis pathway is a ${\text{C}}_6$ molecule or a ${\text{C}}_3$ molecule.

Concept introduction: In the glycolysis metabolic pathway, a glucose molecule is converted into two pyruvate molecules. Two ATP molecules and NADH coenzymes are produced along with pyruvate.

The block diagram to represent an overview of glycolysis is as follows:

From the above diagram, it is concluded that in the overall process of glycolysis, two stages are present.

a) Steps 1 to 3 represents a six-carbon stage $\left({\text{C}}_6\text{ stage}\right)$.

b) Steps 4 to 10 represent a three-carbon stage $\left({\text{C}}_3\text{ stage}\right)$.

In the ${\text{C}}_6$ stage, the intermediates are derivatives of either glucose or fructose. Glucose and fructose contain six carbon atoms. Therefore, they are ${\text{C}}_6$ molecules. The phosphate groups are present in the intermediates.

In the ${\text{C}}_3$ stage, the intermediates are phosphorylated derivatives of glyceraldehyde, pyruvate, glycerate, or dihydroxyacetone, which are derivatives of either acetone or glycerol. Acetone and glycerol contain three carbon atoms. Therefore, they are ${\text{C}}_3$ molecules.

Answer to Problem 13.9EP

Phosphoenolpyruvate is a ${\text{C}}_3$ molecule.

Explanation of Solution

The structure of phosphoenolpyruvate is as follows:

Phosphoenolpyruvate is formed in the ${\text{C}}_3$ stage and it is the phosphorylated derivative of pyruvate. Therefore, it is a ${\text{C}}_3$ molecule.

Conclusion

Phosphoenolpyruvate is formed in the ${\text{C}}_3$ stage and it is the phosphorylated derivative of pyruvate. It contains three carbon atoms. Therefore, it is a ${\text{C}}_3$ molecule.

(c)

Interpretation Introduction

Interpretation: To indicate whether the intermediate $\text{3}-\text{Phosphoglycerate}$ in the glycolysis pathway is a ${\text{C}}_6$ molecule or a ${\text{C}}_3$ molecule.

Concept introduction: In the glycolysis metabolic pathway, a glucose molecule is converted into two pyruvate molecules. Two ATP molecules and NADH coenzymes are produced along with pyruvate.

The block diagram to represent an overview of glycolysis is as follows:

From the above diagram, it is concluded that in the overall process of glycolysis, two stages are present.

a) Steps 1 to 3 represents a six-carbon stage $\left({\text{C}}_6\text{ stage}\right)$.

b) Steps 4 to 10 represent a three-carbon stage $\left({\text{C}}_3\text{ stage}\right)$.

In the ${\text{C}}_6$ stage, the intermediates are derivatives of either glucose or fructose. Glucose and fructose contain six carbon atoms. Therefore, they are ${\text{C}}_6$ molecules. The phosphate groups are present in the intermediates.

In the ${\text{C}}_3$ stage, the intermediates are phosphorylated derivatives of glyceraldehyde, pyruvate, glycerate, or dihydroxyacetone, which are derivatives of either acetone or glycerol. Acetone and glycerol contain three carbon atoms. Therefore, they are ${\text{C}}_3$ molecules.

Answer to Problem 13.9EP

The intermediate $\text{3}-\text{Phosphoglycerate}$ is a ${\text{C}}_3$ molecule.

Explanation of Solution

The structure of $\text{3}-\text{phosphoglycerate}$ is as follows:

The intermediate $\text{3}-\text{phosphoglycerate}$ is formed in the ${\text{C}}_3$ stage and it is the phosphorylated derivative of glycerate. Therefore, it is a ${\text{C}}_3$ molecule.

Conclusion

The intermediate $\text{3}-\text{Phosphoglycerate}$ is formed in the ${\text{C}}_3$ stage and it is the phosphorylated derivative of glycerate. It contains six carbon atoms. Therefore, it is a ${\text{C}}_3$ molecule.

(d)

Interpretation Introduction

Interpretation: To indicate whether the intermediate dihydroxyacetone phosphate

in the glycolysis pathway is a ${\text{C}}_6$ molecule or a ${\text{C}}_3$ molecule.

Concept introduction: In the glycolysis metabolic pathway, a glucose molecule is converted into two pyruvate molecules. Two ATP molecules and NADH coenzymes are produced along with pyruvate.

The block diagram to represent an overview of glycolysis is as follows:

From the above diagram, it is concluded that in the overall process of glycolysis, two stages are present.

a) Steps 1 to 3 represents a six-carbon stage $\left({\text{C}}_6\text{ stage}\right)$.

b) Steps 4 to 10 represent a three-carbon stage $\left({\text{C}}_3\text{ stage}\right)$.

In the ${\text{C}}_6$ stage, the intermediates are derivatives of either glucose or fructose. Glucose and fructose contain six carbon atoms. Therefore, they are ${\text{C}}_6$ molecules. The phosphate groups are present in the intermediates.

In the ${\text{C}}_3$ stage, the intermediates are phosphorylated derivatives of glyceraldehyde, pyruvate, glycerate, or dihydroxyacetone, which are derivatives of either acetone or glycerol. Acetone and glycerol contain three carbon atoms. Therefore, they are ${\text{C}}_3$ molecules.

Answer to Problem 13.9EP

Dihydroxyacetone phosphate is a ${\text{C}}_3$ molecule.

Explanation of Solution

The structure of dihydroxyacetone phosphate is as follows:

The intermediate dihydroxyacetone phosphate is formed in the ${\text{C}}_3$ stage and it is the phosphorylated derivative of dihydroxyacetone. Therefore, it is a ${\text{C}}_3$ molecule.

Conclusion

Dihydroxyacetone phosphate is formed in the ${\text{C}}_3$ stage and it is the phosphorylated derivative of dihydroxyacetone. It contains three carbon atoms. Therefore, it is a ${\text{C}}_3$ molecule.