1. The problem statement, all variables and given/known data Explain why facilitated diffusion, unlike simple diffusion, is both specific and saturable. (Short essay, 4 points) 2. Relevant equations -------------------------- 3. The attempt at a solution Is this a good beginning to an answer? I feel like I can never apply things correctly for my prof. He will tell us facts but never the why or how, so I always feel lost when I get my homework. He really makes me angry. ANYWAY--- Facilitated diffusion is a passive transport of molecules. However, if a membrane is impermeable then molecules can't get through on their own. In facilitated diffusion molecules get through with the help of proteins in the form of ion channels and protein carriers. This makes them specific because the proteins only allow one certain type of molecule in. This also causes facilitated diffusion to be saturable because the proteins can only go through so fast. Their rate of concentration difference will increase, but at one point it will max out and stay constant because the carrier or channel cannot get any faster at transporting the molecules.