Facilitated Diffusion
Facilitated diffusion enables molecules that cannot directly cross the lipid bilayer to diffuse through protein channels. The word facilitate means to help or to make easy. So the protein channels facilitate the diffusion of different molecules across the cell membrane. Protein channels are also called transport proteins or carrier proteins . Larger molecules such as glucose require protein channels to cross the cell membrane. Protein channels have various shapes and are specific for the type of molecule they help across the membrane. The molecules move through the protein channel from an area of higher concentration to an area of lower concentration. Facilitated diffusion does not require energy.
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