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Difference between Diffusion and Facilitated Diffusion

October 3, 2023
written by Sidra Batool

The main difference between diffusion and facilitated diffusion is that diffusion is the passive movement of small, non-polar molecules across a membrane without the involvement of transport proteins, while facilitated diffusion involves the passive transport of polar and large molecules through integral membrane proteins (such as channels or carriers).

Image showing Difference between Diffusion and Facilitated Diffusion

Diffusion vs Facilitated Diffusion

Here are the key differences between diffusion and facilitated diffusion:

CharacteristicDiffusionFacilitated Diffusion
Type of TransportPassive transportPassive transport
Transported MoleculesSmall, non-polar moleculesPolar and large molecules
Transport ProteinsNot involvedIntegral membrane proteins (e.g., channels or carriers)
Energy RequirementNo energy input requiredNo energy input required
Rate of TransportSlowerFaster
SelectivityNon-selective (random movement)Selective (based on specific proteins)
SaturationRarely saturates (rate increases linearly with concentration gradient)Can saturate (limited by the number of transport proteins)