Biological membranes

Cards (16)

  • What are 3 functions of the cell surface membrane ?
    Partially permeable
    site of chemical reaction
    cell communication
  • Extrinsic protein = provide mechanical support or used as cell receptors
  • Intrinsic proteins = carriers/channels involved in the transport of molecules across the membrane
  • Protein channels = tubes that fill with water to enable polar ions to diffuse
  • Carrier proteins = bind to other ions/large molecules and change shape to transport them across membranes
  • What can affect the permeability of bilayer ?
    Temperature and organic solvents
  • What is the affect of organic solvents on cell membrane ?
    They can dissolve the bilayer making the membrane more permeable
  • Osmosis = the movement of water from an area of higher water potential to an area of lower water potential across a partially permeable membrane
  • What modes of transport for particles require ATP?

    Active transport, endocytosis and exocytosis
  • isotonic solution = water potential is the same in solution as the cell
  • Hypertonic solution = water potential of solution is more negative than the cell.
  • Hypotonic solution = water potential is less negative in solution than the cell
  • How does Active transport work ?
    Atp binds to protein inside cell and is hydrolysed to ADP and Pi
    Protein changes shape and opens towards the inside, allowing the molecule to be released
    Pi molecule is then released from the protein so it reverts back to the original shape.
  • Endocytosis = bulk transport of molecules into a cell
  • Exocytosis = bulk transport of molecules out of a cell
  • Pinocytosis = movement of liquids