Facilitatsioonidiffusioon

Facilitated diffusion is a type of passive transport that allows certain molecules to cross the cell membrane with the help of transport proteins. Unlike simple diffusion, which involves the movement of molecules from an area of high concentration to an area of low concentration, facilitated diffusion requires the presence of specific transport proteins embedded in the cell membrane. These proteins facilitate the movement of molecules that cannot easily cross the lipid bilayer on their own, such as glucose, amino acids, and ions.

The process of facilitated diffusion is typically downhill, meaning it occurs from an area of higher concentration to an area of lower concentration. However, in some cases, facilitated diffusion can also occur against a concentration gradient, but this requires the input of energy, usually in the form of ATP, and is known as active transport.

Facilitated diffusion plays a crucial role in various biological processes, including nutrient uptake, waste removal, and signal transduction. It is particularly important in cells that require a high rate of nutrient transport, such as those in the small intestine and the kidneys. The efficiency and specificity of facilitated diffusion are due to the unique structure and function of the transport proteins involved.