Facilitated diffusion

Definition

Facilitated diffusion is a passive transport process where molecules move across the cell membrane via specific transmembrane proteins. It does not require energy and relies on the concentration gradient.

5 Must Know Facts For Your Next Test

1. Facilitated diffusion involves carrier proteins or channel proteins to help transport substances across the cell membrane.
2. It is different from simple diffusion as it requires specific protein structures to facilitate the movement of molecules.
3. Facilitated diffusion transports polar or charged molecules that cannot easily pass through the hydrophobic lipid bilayer.
4. The rate of facilitated diffusion can be influenced by the number of transport proteins available in the membrane.
5. Examples of molecules transported via facilitated diffusion include glucose, ions, and amino acids.

Review Questions

• What role do transmembrane proteins play in facilitated diffusion?
• How does facilitated diffusion differ from simple diffusion?
• Why can't polar or charged molecules pass through the cell membrane without facilitated diffusion?

Related terms

Simple Diffusion: Movement of molecules from an area of higher concentration to an area of lower concentration without using energy or transport proteins.

Active Transport: The process that moves molecules across a cell membrane against their concentration gradient, requiring energy (ATP).

Osmosis: The passive movement of water molecules through a selectively permeable membrane from a region of lower solute concentration to higher solute concentration.