Receptor-mediated endocytosis is a general mechanism whereby cells take up large molecules, each through a corresponding specific receptor. You should know details of the itinerary of the LDL receptor as outlined in the text. A figure that summarizes the different mechanisms of transport is attached. The rate of nonmediated transport of a molecule through a membrane depends on its solubility in the membrane s non-polar core and is driven by it s concentration gradient. Passive-mediated transporters include ionophores such as valinomycin and gramicidin, porins, ion channels and certain transport proteins.
Most ion channels exist either in an open or closed state.
Active transport , in most cases, is drive by ATP hydrolysis. Chapter 10, Membrane Structure and Chapter 11, Membrane Transport of Small Molecules and the Ionic Basis of Membrane Excitability. Explain why lateral diffusion of phospholipids is faster than transverse diffusion in a membrane. Draw the structure of a typical phospholipid. Many types of cells possess receptors that bind steroid hormones.