Question

What is the ultimate source of free energy for secondary active transport?

Short answer

The source of free energy in the glucose transport is the intestinal epithelium and the electrochemical gradient is harnessed to power glucose transport against the concentration gradient.

Step-by-step solution

Introduction

Secondary active transport is when molecules are transported across the cell membrane using energy other thanATP. As a result, theelectrochemical gradientformed by pushing ions out of the cell provides this energy.Co-transportis another name for this mode of transportation.

Free energy for secondary active transport

The electrochemical gradientis created by sodium's primary active transport, which also allows for co-transport.

Extracellular sodium concentrations are substantially greater thanintracellular sodium concentrations because sodium is actively carried out of the cell.

As the surplus sodium tries to permeate into the cell interior, the gradient becomes more energetic.

The glucose transportis the free energy stored in the electrochemical gradient.