BIOLOGY 151 Chapter Notes - Chapter 5: Cell Membrane, Nuclear Membrane, Endoplasmic Reticulum
Document Summary
5. 1 cell membranes are composed of lipids, proteins, and carbohydrates. Phospholipids have both hydrophilic and hydrophobic regions. As a result, they spontaneously form structures such as micelles and bilayers when placed in an aqueous environment. Membranes are uid, meaning that membrane components are able to move laterally in the plane of the membrane. Membrane uidity is in uenced by length of fatty acid chains, presence of carbon carbon double bonds in fatty acid chains, and amount of cholesterol. Many membranes also contain proteins that span the membrane (transmembrane proteins) or are temporarily associated with one or other layer of the lipid bilayer (peripheral proteins). 5. 2 the plasma membrane is a selective barrier that controls the movement of molecules between the inside and the outside of the cell. Selective permeability results from the combination of lipids and proteins that makes up cell membranes. Passive transport is the movement of molecules by diffusion, the random movement of molecules.
