Movement

We know the basics of diffusion.

The Passive movement of molecules from an area of High concentration to an area of Low concentration, along the concentration gradient.

Osmosis

This is a special type of diffusion, specifically concerned with the movement of water molecules.

But what happens if we want to move against the gradient?

Or the molecule is too large to diffusion across the membrane?

This is where active transport comes in. We put energy into the equation to go against the concentration gradient.