Vesicle Formation (HL) (HL IB Biology)

• Vesicles are membrane-bound sacs used for transport and storage
• There are many sorts of vesicles including:
  • Peroxisomes - these contain enzymes which digest fatty acids
  • Lysosomes - these contain lytic enzymes which digest cellular waste or harmful substances
  • Transport vesicles - these are used to move various molecules within the cell
  • Secretory vesicles - these are responsible for transporting substances out of the cell via exocytosis

Role of Clathrin

• Clathrins are proteins that help with the formation of vesicles
• They line the vesicles which are transporting molecules between membrane-bound compartments
• The following process takes place:
  1. A clathrin coated pit is formed on the surface of the cell membrane
  2. Receptor proteins on the cell surface bind to the target molecules
  3. Once enough target molecule are attached, cytoskeleton proteins help the clathrin pit to deepen and eventually seal off, trapping the target molecules inside
  4. A vesicle is now formed

Vesicle formation diagram

Clathrin proteins play an important role in the formation of vesicles