Lipid Bilayer

• What is the role of Biological membranes

  To separate cell contents and the surroundings, Compartmentalise organelles and allow for selective permeability
• What are the features of the Fluid mosaic model

  • Rapid lateral movement of phospholipids
  • Cholesterol stabilises the membrane
  • High temperatures reduce movement
  • Unsaturated fatty acids cause kinks enhancing fluidity
• Types of proteins

  • Integral: Transmembrane proteins
  • Peripheral: loosely bound via proteins
  • Lipid-anchored: Covalently bonded to lipids
• Membrane carbohydrates

  • Short and branched
  • Used as identity tags [antigens]
  • Present as glycolipids or glycoproteins
• Why are protein channels needed

  Polar molecules are impeded by the hydrophobic core of the bilayer
• Transport proteins

  Enable the movement of polar molecules
• Types of transport proteins

  • Channels
  • Carriers
• Role of Protein channels

  Allow for passive diffusion
• Role of Carrier proteins

  Allow for active movement