BIOB10H3 Chapter Notes - Chapter 4: Lipid Bilayer, Partition Coefficient, Solvent
Document Summary
Chapter 4 the structure and function of the plasma membrane. 4. 7 the movement of substances across cell membranes. It must retain the dissolved materials of the cell, and it must allow the necessary exchange of materials into and out of the cell. Two means of movement of substances, passively by diffusion or actively by an energy coupled transport process. Net flux indicates movement of substance into cell (influx) and out of cell (efflux) is not balanced. Simple diffusion through lipid bilayer, simple diffusion through an aqueous protein loined channel, diffusion that is facilitated by a protein transporter, and active transport which requires a pump. Diffusion is a spontaneous process in which a substance moves from a region of high concentration to a region of low concentration, eventually eliminating the concentration difference. The substance must be present at a higher concentration on one side of the membrane, and the membrane must e permeable to the substance.