Exocytosis - Endocytosis

The optimal functioning of the cell depends closely on the exchanges between the extracellular and intracellular environments, these are separated from each other by the cell membrane. Among the various mechanisms for transferring molecules on both sides of the membrane are endocytosis and exocytosis.

• Endocytosis occurs when molecules are transported into a cell. 
• Exocytosis is when molecules are secreted outside the cell.