phospholipid bilayer

• phospholipids

  • a molecule of glycerol
  • a phosphate group/phosphate head
  • 2 fatty acid tails
• polar head

  • interacts with polar water molecules
  • hydrophilic
• fatty acid tails

  • non polar
  • cannot interact with polar molecules
  • hydrophobic
• proteins

  • involved in cell transport and communication
  • can be intrinsic or extrinsic
• cholestrol

  • regulates membrane fluidity
  • stops phospholipid tails packing too closely together at low temps
  • also stabilises membranes at high temps
  • cholestrol can increase mechanical strength and stability of membranes
• glycolipids and glycoproteins

  • aid cell to cell communication
  • bind to substances at cells surface eg hormones
  • some act as antigens for cell to cell recognition
• fluid mosaic model

  • scattered pattern of proteins looks like a mosaic
  • phospholipids and proteins can move around the bilayer via diffusion= fluid

  -small non-polar molecules can pass through gaps

  -large polar molecules must pass through membrane proteins(channel or carrier)