plasma membrane structure

• Plasma membrane


  The membrane that surrounds a cell or organelle
• The plasma membrane structure is the same whether it's on the surface of a cell or the outside of an organelle
• Fluid mosaic model


  The mixture of different components that make up the plasma membrane, which can move fluidly
• Components of the plasma membrane

  • Phospholipids
  • Proteins
  • Glycoproteins
  • Glycolipids
  • Cholesterol
• Phospholipid bilayer


  • Hydrophilic heads facing outwards, hydrophobic tails facing inwards
• Saturated fatty acid


  Fatty acid with no double bonds
• Unsaturated fatty acid


  Fatty acid with double bonds
• Cholesterol


  • Restricts the lateral movement of molecules, making the membrane less fluid
• Peripheral proteins


  Proteins that are attached to only one side of the membrane
• Integral proteins


  Proteins that span the entire width of the membrane
• Protein channels


  • Allow the passage of water-soluble ions and small molecules
• Carrier proteins


  • Bind to larger molecules like glucose or amino acids and transport them across the membrane
• Partially permeable membrane


  Only certain molecules can diffuse through the membrane by simple diffusion
• Lipid-soluble molecules like hormones, oxygen, and carbon dioxide can diffuse through the membrane
• Water-soluble and large polar molecules cannot pass through the membrane by simple diffusion