Because materials move from high concentration to low concentration by simple diffusion, and they move the same way by facilitated diffusion, why do cells make proteins to carry out facilitated diffusion? Isn't this just a waste of energy?© BrainMass Inc. brainmass.com October 9, 2019, 7:56 pm ad1c9bdddf
Plasma membrane is a dynamic quasi-fluid structure of a cell. Chemically it is made up of protein and lipids bilayer. It is selective-permeable and allows the passage of specific molecules needed by cell.
Lipid bilayer is impermeable to some of the vital molecules like glucose, sodium ions, chloride ions etc. Their transport must therefore be "facilitated" by proteins ...
This solution discusses the plasma membrane, lipid bilayer, carrier protons and ion channels in 236 words.