What is facilitated diffusion and how does it work?

Facilitated diffusion is a type of passive transport that allows substances to cross cell membranes with the help of carrier proteins.

In more detail, facilitated diffusion is a process that enables the movement of specific molecules across cell membranes. This process is passive, meaning it does not require the cell to expend energy. Instead, it relies on the concentration gradient, moving substances from areas of high concentration to areas of low concentration until equilibrium is reached.

The key players in facilitated diffusion are special proteins known as carrier proteins. These proteins are embedded in the cell membrane and have a specific shape that allows them to bind with a particular molecule or ion. When the molecule binds to the carrier protein, it causes a change in the protein's shape, effectively transporting the molecule across the cell membrane. Once the molecule is released on the other side, the carrier protein returns to its original shape, ready to transport another molecule.

It's important to note that facilitated diffusion is selective, meaning only specific molecules can be transported. This selectivity is determined by the shape and size of the carrier protein's binding site. For example, glucose molecules are transported into cells via facilitated diffusion using a specific glucose transporter protein.

In summary, facilitated diffusion is a crucial process that allows cells to regulate the movement of specific substances in and out of the cell. It is a passive process that relies on concentration gradients and the action of carrier proteins to transport molecules across cell membranes.