ICA 12: Building and crossing a Cell Membrane List THREE functions of a cell membrane: efit ell trois What can enter 2. Trotects the Cell meninune protein in Jernet w/ Why would a cell have internal membranes (membranes separate from the cell membrane)? regulation nly cal processes. of cellular For each of the following molecules, state whether it would be chemically able to cross a membrane made of a phospholipid bilayer and why. Hint: this is mostly a review of the chemical properties at biologica molecules. ripid bilayer molecular oxygen 3duble in molecular carbon dioxide souble in lipid bilayor v estrogen fat Sauble unchorged glucose No, large ond valine lysine calcium ions to X DNA polymerase No, water small t uncharged membrane proteins hydro a virus