Embeded protein:
Embeded protein:
Higher Lower concentration concentration Diffusion through the lipid layer Lipid-soluble molecules such as O2 and CO2 diffuse freely through the plasma membrane Diffusion through channels Some polar and charged molecules diffuse through protein channels that span the membrane.Water is a typical example. Facilitated transport Certain molecules bind to a protein,triggering a change in protein shape that transports the molecule across the membrane.Glucose typically enters cells by this method