Describe the primary mechanisms by which cells import and export macromolecules

In addition to moving small ions and molecules through the membrane, cells also need to remove and take in larger molecules and particles. Some cells are even capable of engulfing entire unicellular microorganisms. You might have correctly hypothesized that the uptake and release of large particles by the cell requires energy. A large particle, however, cannot pass through the membrane, even with energy supplied by the cell.

There are two primary mechanisms that transport these large particles: endocytosis and exocytosis.

What You’ll Learn to Do

• Describe endocytosis and identify different varieties of import, including phagocytosis, pinocytosis, and receptor-mediated endocytosis
• Identify the steps of exocytosis

Learning Activities

The learning activities for this section include the following:

• Endocytosis
• Exocytosis
• Self Check: Endocytosis and Exocytosis