Cell-surface Membrane

Cards (3)

  • What is the phospholipid bilayer?
    Has a hydrophobic tail and a hydrophilic head
    Acts as a barrier to diffusion of many substances
    Small non-polar (without charge) molecules can pass through by diffusion due to the middle being hydrophobic
  • What is facilitated diffusion?
    Diffusion that is assisted by proteins in the membrane
    Ions and small polar molecules are transported by channel proteins that act like pores in the membrane
    Some of these can open and close; they are called gated channels
    Larger polar molecules use carrier proteins
    These are specific to the substance they are transporting
    The substance binds to the inside of the protein, and the protein then changes shape, transferring the substance to the other side
  • What is co-transport?
    The coupled movement of substances across a membrane
    One substance moves down a concentration gradient, driving the movement of the other substance in the same direction