Fluid Mosaic Model Components

  • Created by: Freja
  • Created on: 12-04-21 22:27
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  • Fluid Mosaic Model
    • Extrinsic Proteins
      • Present in one side of the bilayer.
      • Normally have hydrophilic R-groups on their surface.
    • Phospholipid Bilayer
      • Has a hydrophilic head, which attracts water and a hydrophobic tail which repels water.
        • The phosphate heads sandwich the fatty aids tails, which forms a hydropho-bic core.
          • Doesn't allow water-soluble molecules (like ions) through.
      • Provides a barrier to large polar molecules.
      • Fat soluble substances/ very small molecules can pass straight through.
      • 2 layers
    • Cholestrol
      • A type of lipid.
      • Positioned between the phospho-lipids and binds to the hydrophobic tails of the phospholipid, causing them to pack more closely together. This makes the membrane less fluid and more rigid.
      • Reduces permeability to charged particles.
      • Hydrophobic ends interact with tails pulling them together.
    • Intrinsic Proteins
      • Span the width of membrane (transmem-brane proteins).
      • Amino acids with hydrophobic R-groups.
      • Channel Proteins
        • Provide a hydrophilic channel.
        • Allowing passive movement (without ATP) down the concentration gradient.
        • For polar molecules/ions down a concentration gradient.
      • Carrier Proteins
        • Plays a role in passive and active transport into cells.
        • They change shape to move substance from one side to the other.
    • Glycolipids
      • Lipids with attached carbohydrate chains.
      • These molecules are cell markers/ antigens and can be recognised by the immune system as self.
    • Glycoproteins
      • Intrinsic proteins, embedded in the cell-surface membrane.
      • Has an attached carbohydrate chains of varying lengths and shapes.
        • It the recognition for chemicals
      • Plays a role in cell adhesion (when cells join together to form tight junctions in certain tissues) and as receptors for chemical signnals.
      • Has receptors for hormones, enzymes etc
      • When  chemical bind to receptors it elicits a response from the cell- this is cell signalling
        • Some drugs act by binding to cell receptors.
    • Propsed in 1972
    • Protein molecules are scattered throughout the bilayer, like tiles in a mosaic


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