What characterizes facilitated diffusion?

Facilitated diffusion is characterized by the movement of molecules across a membrane through specific protein channels. This process allows substances that cannot readily cross the lipid bilayer of the cell membrane, such as polar or charged molecules, to enter or exit the cell. The protein channels serve as selective gateways that facilitate this movement, ensuring that the process is both efficient and selective based on the size, charge, or specific chemical properties of the molecules.

In facilitated diffusion, the movement of molecules occurs along their concentration gradient, meaning substances move from areas of higher concentration to areas of lower concentration without requiring energy. This distinguishes facilitated diffusion from active transport processes that do require energy to move substances against their concentration gradients. The transport proteins can either be carrier proteins that change shape to move the molecule across or channel proteins that create a passageway through the membrane.

This understanding of facilitated diffusion helps clarify the roles and mechanisms of cellular transport processes necessary for maintaining homeostasis and the overall function of cells.