Structure of Eukaryotic Cells

Cell-surface membrane

• Controls the movement of substances in and out of cell
• Phospholipds form a bilayer
  • Hydrophillic heads point outwards- attracted by water on both sides
  • Hydrophocic heads point inwards- repelled by water on both sides
  • Prevent water-soluble substances from entering/ leaving cell
  • Make membrance flexible and self-sealing
• Proteins embedded in phospholipd bilayer
  • Give mechanical support/ act as receptors for molecules (e.g. hormones) with glycolipids 
  • Protein channels allow water-soluble ions to diffuse across membrane
  • Carrier proteins bind to ions or molecules (e.g. glucose) and change shape to move them across membrane
• Cholesterol
  • Hydrophobic so prevent loss of water/ dissolved ions from cell
  • Pull together fatty acid tail to reduce their movement
  • Make membrane less fluid at high temperatures
• Glycolipids
  • Carbohydrate protion extends into watery environemnt outside cell to act as a receptor
  • Help cells attach to each other 
• Glycoproteins
  • Act as receptors
  • Allow cells to recognise each other (e.g. lymphocytes recognise an organism's own cells)

Nucleus

• Contains genetic material and controls cell activities
• Nuclear envelope
  • Double membrane surrounding nucleus
  • Controls the movement…