How does facilitated diffusion differ from active transport?

Facilitated diffusion differs from active transport as it doesn't require energy, while active transport does.

Facilitated diffusion and active transport are two fundamental mechanisms that cells use to move substances across their membranes. However, they operate differently and have distinct characteristics.

Facilitated diffusion is a type of passive transport that allows substances to cross cell membranes with the help of carrier proteins. It's a natural process that doesn't require the cell to expend energy. Instead, substances move from an area of high concentration to an area of low concentration, following their concentration gradient. This process continues until the concentration of the substance is equal on both sides of the membrane, achieving equilibrium. Examples of substances that use facilitated diffusion include glucose and ions, which cannot pass through the lipid bilayer of the cell membrane without assistance.

On the other hand, active transport is a process that requires energy in the form of ATP (adenosine triphosphate) to move substances against their concentration gradient, from an area of low concentration to an area of high concentration. This process is carried out by specific proteins embedded in the cell membrane, known as pumps. These pumps use the energy from ATP to change their shape and move substances across the membrane. Active transport is crucial for maintaining the cell's internal environment, allowing it to accumulate essential nutrients and expel waste products. An example of active transport is the sodium-potassium pump, which maintains the electrochemical gradient necessary for nerve impulse transmission.

In summary, while both facilitated diffusion and active transport involve the movement of substances across the cell membrane with the help of proteins, they differ in their energy requirements and the direction of substance movement. Facilitated diffusion is a passive process that moves substances down their concentration gradient without the need for energy, while active transport is an energy-requiring process that moves substances against their concentration gradient.