Basic objective of this lecture is to present on “Transport through Cell Membranes”. Diffusion is the net movement of molecules (or ions) from a region of their high concentration to a region of their lower concentration. The molecules move down a concentration gradient. Molecules have kinetic energy, which makes them move about randomly. Here also present on what determines the rate of diffusion. The steepness of the concentration gradient: temperature; the surface area and the type of molecule or ion diffusing.