BILD 1 Chapter Notes - Chapter 5: Fluid Mosaic Model, Lipid Bilayer, Transport Protein
Document Summary
Controls traffic into and out of the cell it surrounds. Selective permeability: allows some substances to cross more easily than others. Amphipathic molecule: both hydrophilic and hydrophobic region (ex. phospholipid) Fluid mosaic model: membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids, proteins not randomly distributed. Membrane is held together by hydrophobic interactions. Movement is sideways, phospholipids are rapid, proteins are slower. Remains fluid as temperature decreases until phospholipids settle into a closely packed arrangement and membrane solidifies. When solid, permeability changes and enzymatic proteins may become inactive. When too fluid, cannot support protein function. Integral proteins: penetrate the hydrophobic interior of the lipid bilayer. Peripheral proteins: not embedded in the lipid bilayer, loosely bound to the surface of the membrane. Enzymatic activity: a protein built into membrane with enzyme where active site is exposed to substances, several enzymes may be carried out as a team.
