What is facilitated diffusion?

Facilitated diffusion is a type of passive transport in which molecules or ions move across a cell membrane with the help of specific transport proteins. Unlike simple diffusion, facilitated diffusion requires the presence of these specialized proteins to facilitate the movement of substances across the membrane. These transport proteins act as channels or carriers, allowing specific molecules or ions to pass through the membrane down their concentration gradient. Facilitated diffusion does not require energy expenditure by the cell and is used for the transport of larger or charged molecules that cannot easily cross the lipid bilayer of the cell membrane.