Why do essential substances like sugars and amino acids often require facilitated diffusion?

Answer

They are too large or too polar to pass effectively through the fatty, nonpolar core of the lipid bilayer.

While moving down their gradient, large or polar molecules cannot easily cross the nonpolar lipid core and thus require assistance from specific transport proteins.

Why do essential substances like sugars and amino acids often require facilitated diffusion?

#Videos

In Da Club - Membranes & Transport: Crash Course Biology #5

regulationtransportcellmembrane