What does a cell membrane let through?

Jan 20, 2016

It allows smaller, non-polar and non-charged molecules through such as ${O}_{2} , C {O}_{2}$ etc. The diffusion of water through the membrane is called osmosis.
However, it doesn't allow charged molecules (such as K+, Na+, H+) or larger molecules such as glucose (${C}_{6} {H}_{12} {O}_{6}$) directly through the bilayer; instead these must go through protein channels.