Biological membranes

• Which parts of the phospholipid bilayer are hydrophobic and which are hydrophilic 


  Phosphate group head is hydrophilic and fatty acid chain tails are hydrophobic
• Can charged particles diffuse through the membrane


  no they must use carrier/channel proteins
• What is the purpose of cholesterol in biological membranes 


  to control fluidity - keep membrane fluid at low temperatures and stop it from coming too fluid at higher temperatures
• How can cell-surface membranes have a part in cell signalling


  Things like hormones can bind to the extrinsic proteins in the surfaces of the membrane in order to signal inside cells
• What can diffuse through the plasma membrane


  small non-polar molecules
• How would glucose get across a membrane


  using a channel protein - molecule too big to diffuse across