The plasma membrane protects the integrity of the interior of the cell by allowing certain substances in, while keeping other substances out

The plasma membrane protects the integrity of the interior of the cell by allowing certain substances in, while keeping other substances out.

• Summarize the manner in which small molecules are permitted to pass through the membrane ensuring you explain the difference between passive, facilitated, active, and coupled transport by comparing and contrasting them.
• Finally, explain the difference between endocytosis and exocytosis and provide an example of a molecule (remembering to state its function) that is transferred using this method.