BIOL150 Chapter Notes - Chapter 19: Signal Transduction, Exocytosis, Amphiphile
Document Summary
Bulk transport methods exocytosis & endocytosis (3 parts: phagocytosis, pinocytosis, & receptor mediated endocytosis) Exocytosis use vesicles to move large items out of the cell. Endocytosis: use vesicles to move large items into the cell. Pinocytosis is cell drinking, the cell dissolves the material taken into the cell. Receptor mediated endocytosis brings specific target molecules into the cell. Receptors embed in the membrane bind to a target molecule called ligand. Phospholipids form the basic structure of the membrane while sterols help maintain the proper fluidity of the membrane. Membrane proteins have a number of functions including transport, signal transduction, cell-cell communication, structural stability and enzymatic activity. The hydrophobic membrane interior surrounded by two hydrophilic regions requires any molecule anchored to the membrane to be amphipathic. The selective permeability of the membrane is due to its amphipathic nature. Most molecules that are large, polar or charged cannot cross the membrane without assistance.