AP BIOLOGY

Detailed explanation-1: -In facilitated diffusion, molecules diffuse across the plasma membrane with assistance from membrane proteins, such as channels and carriers. A concentration gradient exists for these molecules, so they have the potential to diffuse into (or out of) the cell by moving down it.

Detailed explanation-2: -Two classes of proteins that mediate facilitated diffusion are generally distinguished: carrier proteins and channel proteins. Carrier proteins bind specific molecules to be transported on one side of the membrane.

Detailed explanation-3: -Facilitated Diffusion Requires Membrane Carrier Proteins Facilitated diffusion is also calledcarrier-mediated diffusion because a substance transported in this manner diffuses through the membrane with the help of a specific carrier protein. That is, the carrierfacilitates diffusion of the substance to the other side.

Detailed explanation-4: -Facilitated diffusion requires membrane proteins to transport biological molecules. Simple diffusion is one that occurs unassisted by membrane proteins. Since membrane proteins are needed for transport in facilitated diffusion, the effect of temperature is often more pronounced than in simple diffusion.

Detailed explanation-5: -To facilitate these transfer of substances across the membrane, certain integral membrane proteins or the transmembrane proteins are required. They are channel proteins and carrier proteins.