Q. 3 - Biology

Question

Figure 6.14One ATP molecule's hydrolysis releases 7.3 kcal/mol of energy (∆G = −7.3 kcal/mol of energy). If it takes 2.1 kcal/mol of energy to move one Na+across the membrane (∆G = +2.1 kcal/mol of energy), how many sodium ions could one ATP molecule's hydrolysis move?

Step-by-Step Solution

Answer

The three sodium ions can be driven by the hydrolysis of one ATP molecule.

Step 1. Introduction

The ATP molecules hydrolysis is a catabolic process in which energy reserved in the high-energy phosphoanhydride bond is discharged when this bond is dissociated or broken.

Step 2. Explanation

The three sodium ions could be transferred by one ATP molecule hydrolysis. The ∆G  of the related reaction must be negative. 6.3 kcal of energy (2.1 kcal × 3 Na+ ions = 6.3 kcal) is utilized to transfer 3 sodium ions across the membrane. 7.3 kcal of energy is supplied by the hydrolysis of ATP which is more than sufficient to power the reaction. The transfer of 4 sodium ions across the membrane, would take approximately 8.4 kcal of energy, which is more than the energy supplied by 1 ATP molecule.