Q. 18.28 - An Introduction to General, Organic, and Biological Chemistry

Question

How many $\mathrm{ATP}$ or $\mathrm{NADH}$ are produced (or required) in each of the following steps in glycolysis?

a. $1,3-bisphosphoglycerate$ to $3-phosphoglycerate$

b. $fructose-6-phosphate$ to $fructose-1,6-bisphosphate$

c. $phosphoenolpyruvate$ to $pyruvate$

Step-by-Step Solution

Answer

(a) The two molecules of $\mathrm{ATP}$ are produced when $1,3-bisphosphoglycerate$ changes to $3-phosphoglycerate$

(b) The one molecule of data-custom-editor="chemistry" $\mathrm{ATP}$ is required for $fructose-6-phosphate$ to $fructose-1,6-bisphosphate$

(c) The two molecules of data-custom-editor="chemistry" $\mathrm{ATP}$ are produced when $phosphoenolpyruvate$ changes to $pyruvate$

Part (a) Step 1: Given information

We need to find the no. of $\mathrm{ATP}$ molecules in each of the given steps in glycolysis.

Part (a) Step 2: Explanation

We know that 

The phosphate transfer that occurs in $1,3 bisphosphoglycerate$ to give data-custom-editor="chemistry" $3-\mathrm{phosphoglycerate}$ produces two molecules of data-custom-editor="chemistry" $\mathrm{ATP}$. $Phosphoglycerate$ kinase catalyzes this phosphate transfer. A phosphate group from $1,3-bisphosphoglycerate$ is transferred to data-custom-editor="chemistry" $\mathrm{ADP}$ molecules in this step, generating data-custom-editor="chemistry" $2 \mathrm{ATP}$ molecules. The data-custom-editor="chemistry" $\mathrm{ATP}$ expenditure in steps $1$ and $3$ of the glycolytic pathway was balanced out by this procedure.

Part (b) Step 1: Given information

We need to find the no. of $\mathrm{ATP}$ molecules in each of the given steps in glycolysis. 

Part (b) Step 2: Explanation

We know that

To convert $fructose-6-phosphate$ to $fructose-1,6 bisphosphate$, one data-custom-editor="chemistry" $\mathrm{ATP}$ molecule is required. $Phosphofructokinase-1$, a glycolysis regulating enzyme, catalyzes the phosphorylation of data-custom-editor="chemistry" $\mathrm{fructose}-6-\mathrm{phosphate}$ to $fructose-1,6 bisphosphate$. data-custom-editor="chemistry" $\mathrm{ATP}$ is hydrolyzed to data-custom-editor="chemistry" $\mathrm{ADP}$ in this process, and the phosphate group produced during data-custom-editor="chemistry" $\mathrm{ATP}$ hydrolysis is transferred to carbon of $fructose-6-phosphate$, resulting in $fructose-1,6-bisphosphate$ production.

Part (c) Step 1: Given information

We need to find the no. of $\mathrm{ATP}$ molecules in each of the given steps in glycolysis. 

Part (c) Step 2: Explanation

We know that

Two $\mathrm{ATP}$ molecules are produced when $phosphoenolpyruvate$ is converted to $pyruvate$. Pyruvate kinase, another glycolysis regulating enzyme, catalyzes this substrate phosphorylation. The phosphate groups from the two phosphoenolpyruvate molecules are converted to $\mathrm{ADP}$ molecules, producing two $\mathrm{ATP}$ molecules, and this process is enabled by pyruvate kinase's involvement in the metabolic process.