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Biology Simulations
Cells & membranesA-level

Membrane transport

What determines how a molecule crosses a cell membrane?

Compare four routes across a cell membrane, from simple diffusion to a pump powered by ATP.

Open simulation

Explore at your own pace. Pause, look closer, play again.

Membrane transport simulation showing a protein pore, phospholipids and ions.
Membrane transportView from the simulation

Look closer.

  1. Compare simple diffusion, channels and carrier proteins.
  2. Change the concentration gradient to explore net movement.
  3. Switch ATP off and on to investigate the sodium–potassium pump.