exocytosis

• • Some substances produced by the cell (e.g. digestive enzymes, hormones, lipids) need to be released from the cell - this is done by exocytosis.
  • Vesicles containing these substances pinch off from the sacs of the Golgi apparatus and move towards the plasma membrane.
  • The vesicles fuse with the plasma membrane and release their contents outside the cell.
  • Some substances (like membrane proteins) aren't released outside the cell - instead they are inserted straight into the plasma membrane.
• Exocytosis also uses ATP as an energy source.