The Fluid Mosaic Model

• The membrane structure is mainly composed off...


  Phospholipid Bilayer
• Phospholipid Function

  • Allow lipid-soluble substances to enter and leave cell
  • Prevent water-soluble substances to enter and leave cell
  • Make membrane flexible
• What are Intrinsic Proteins?


  Proteins that extend completely through the Phospholipid Bilayer
• What are Extrinsic Proteins?


  Proteins that are only partially embedded in the Phospholipid Bilayer
• What functions do Proteins have in the Phospholipid?


  • Transport of certain substances
  • Anchors for the cytoskeleton of the cytoplasm
  • Receptors, bind to information providing molecules like hormones
  • Enzymatic Activity, catalysing various reactions related to the plasma membrane
• Proteins for Transport


  • Channel Proteins act like pores for polar molecules of the right size in facilitated diffusion
  • Carrier Proteins allow specific molecules to attach to cause a conformational change, which transports the molecule through the membrane and onto the other side through facilitated diffusion. If energy is required to act against the concentration gradient, it is active transport
• What does Cholesterol do in the Cell Membrane?


  • Reduces lateral movement
  • Makes it less fluid at high temperatures
  • Prevent leakage of water and ions from cell
• What do Glycolipids do in the Cell Membrane?


  Act as recognition site for cells to attach to each other
• What are Glycolipids?


  Carbohydrates covalently bonded with a lipid
• What do Glycoproteins do in the Cell Membrane?


  Act as Cell-Surface receptors for hormones and neurotransmitters, and allow cells to recognise one another
• What are Glycoproteins?


  Carbohydrates attached to other Extrinsic Proteins