Transport across a cell membrane



Diffusion: Movement of molecules from a high concentration gradient to a low concentration gradient. This is a passive process.

Osmosis: Movement of water from low water potential to high water potential. This is a passive process.

Facilitated Diffusion: Process where molecules that are too large to diffuse across the membrane are aided by channel proteins that provide them with a route to travel. From a high concentration gradient to a low concentration gradient, this is a passive process.

Active Transport: Transport of molecules against the concentration gradient. Molecules are forced through a channel/carrier protein with the aid of energy in the fom of ATP. This is an active process as it requires energy.

Endocytosis: Movement of material in bulk into the cell. In the form of a discrete package that fuses with the plasma membrane releasing matter into the cell.

Exocytosis: Movement of material in bulk out of the cell. A discrete package fuses with the plasma membrane releasing matter out of the cell.


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