transport across a membrane

• what do all eukaryotic cell membranes consist of


  a phospholipid bilayer and proteins
• what type of substances does a phospholipid bilayer allow to enter and exit the cell


  non-polar, hydrophobic, uncharged
• what do phospholipids do in cell membranes


  control the movement of substances
• what does cholesterol do in cell membranes

  regulates the fluidity of the membrane, restricts movement of phospholipids/proteins which prevents water/ions from leaking out of the cell
• what do glycolipids do in cell membranes


  act as recognition sites for other cells, allowing cells to attach to one another to form tissues
• what proteins are found in a cell membrane


  surface proteins, glycoproteins, transport proteins
• what do surface proteins do in a cell membrane


  provide mechanical support for the membrane
• what do glycoproteins do in a cell membrane


  act as recognition sites for foreign sites or specific chemicals allowing specific hormones outside the cell to trigger a response inside the cell
• what do transport proteins do in a cell membrane


  help transport substances across a membrane
• why is it called a fluid-mosaic model


  fluid: the phospholipids and some proteins can move in their layer of the membrane

  mosaic: the random scattering of proteins