* Passive Transport: Facilitated diffusion is a type of passive transport, meaning it doesn't require the cell to expend energy (ATP).

* Proteins as Channels: Special proteins embedded in the cell membrane act as channels or carriers. These proteins are highly specific for the molecules they transport.

* Concentration Gradient: Movement across the membrane is driven by the concentration gradient. Molecules move from an area of high concentration to an area of low concentration.

Examples of Facilitated Diffusion:

* Glucose Transport: The glucose transporter protein (GLUT) facilitates the movement of glucose into cells, following its concentration gradient.

* Ion Channels: Specific ion channels allow the passage of ions like potassium (K+), sodium (Na+), or chloride (Cl-) across the membrane, following their electrochemical gradients.

Key Points:

* No Energy Required: Facilitated diffusion relies on the natural tendency of molecules to move down their concentration gradient.

* Specificity: The proteins involved are very selective in the molecules they transport.

* Faster than Simple Diffusion: Facilitated diffusion is faster than simple diffusion because the proteins provide a pathway for molecules to cross the membrane.

In contrast to active transport, which requires energy, facilitated diffusion is a passive process that leverages the energy stored within the concentration gradient to move molecules.