Facilitated diffusion is the process by which molecules move across a cell membrane with the help of a carrier molecule. Carrier molecules are proteins that are located in the cell membrane and that have a specific binding site for the molecule that is being transported. When a molecule binds to a carrier molecule, the carrier molecule changes shape and transports the molecule across the cell membrane. Facilitated diffusion is a passive process, meaning that it does not require energy from the cell.
Active transport is the process by which molecules move across a cell membrane against a concentration gradient. Active transport is an active process, meaning that it requires energy from the cell. Active transport is carried out by proteins that are called pumps. Pumps are proteins that use energy from ATP to move molecules across the cell membrane.
The main difference between facilitated diffusion and active transport is the direction in which the molecules are moving. In facilitated diffusion, the molecules are moving down a concentration gradient, while in active transport, the molecules are moving against a concentration gradient. Another difference between facilitated diffusion and active transport is the energy requirement. Facilitated diffusion is a passive process, while active transport is an active process.
