Diffusion¶
Use this interactive to watch how random particle motion can still produce a net movement from higher to lower concentration across a membrane. It is most useful for seeing that diffusion is about overall pattern, not particles marching in a single direction.
This model keeps the membrane fully permeable so the gradient is easier to track. Use it for simple diffusion of small non-polar molecules such as oxygen and carbon dioxide, not as a model of facilitated diffusion, active transport, or the true scale and crowding of a real membrane.