Bio1151 Chapter 7 Membrane Structure and Function
  1. The plasma membrane is a "fluid mosaic" made of         with a mosaic of           embedded in it, and exhibits            permeability.

  2. Membranes are made of                which form a bilayer with embedded proteins.

  3. Selective               allows some material to cross the plasma membrane.

    •            (passive transport) is the tendency for molecules to spread out evenly down their                gradient.

      • Osmosis determines the           of the environment across a membrane.

      • Organisms without cell        must have adaptations for                 to maintain water balance.

      • Plant cells fare best in            environments.

    •              diffusion is the movement of molecules across the membrane facilitated by            proteins,       the concentration gradient.

    •         transport moves molecules          their concentration gradient and requires energy.

    • Large molecules are moved into and out of cells by bulk transport mechanisms of              and             .
      • In              , the cell takes in macromolecules by forming vesicles from the plasma membrane via invagination.

      • In             , transport           migrate to the plasma membrane, fuse with it, and release their contents.