* Specificity: Facilitated diffusion is selective. The membrane protein binds to a specific molecule, allowing only that molecule to pass through. This is unlike simple diffusion where any small molecule can pass through the membrane.
* Concentration Gradient: Like simple diffusion, facilitated diffusion still relies on a concentration gradient. The molecule will move from a region of high concentration to a region of low concentration.
* No Energy Input: Facilitated diffusion does not require the cell to expend energy. The movement of the molecule is driven by the concentration gradient.
Here's an analogy: Imagine a crowded doorway. You (the molecule) can't get through because there are too many other people (other molecules) in the way. Now imagine a friendly bouncer (the membrane protein) who knows you and helps you through the door (the membrane). That's essentially how facilitated diffusion works.
Examples of Facilitated Diffusion:
* Glucose transport: Glucose is transported into cells using specific membrane proteins like GLUT1.
* Amino acid transport: Amino acids are transported into cells using specific membrane proteins like LAT1.
* Ion transport: Some ions like potassium and sodium are transported across membranes by specific ion channels.
Key Point: Facilitated diffusion is a passive process that requires a membrane protein to help move molecules across the membrane, but it does not require the cell to expend energy.
