[Animation] - How the Sodium Potassium Pump Works

How can more molecules be transported into areas with high concentrations of the molecule?

Cells often need to create concentration gradients across membranes. The concentration of a molecule is much higher on one side of the membrane than the other when a concentration gradient exists. In order to create or maintain a concentration gradient, individual molecules must be moved from an area of low concentration to an area of high concentration. This cannot occur through passive diffusion, in fact diffusion will cause the gradient to break down. Only active transport, which requires both specialized transport molecules and the expenditure of energy can drive molecules up a concentration gradient. The sodium potassium pump is an important and well understood example of active transport.

<a rel="nofollow" href="https://http://glencoe.mcgraw-hill.com/sites/dl/free/9834092339/291136/NAKpump.swf" target="_blank">https://http://glencoe.mcgraw-hill.com/sites/dl/free/9834092339/291136/NAKpump.swf</a>