Question

Why is exocytosis considered an active transport mechanism?  Where and why does the cell have to use energy?

Answer 1

Exocytosis is defined as the process by virtue of which cells excrete waste and other large molecules from the cytoplasm to the cell exterior.

Active transport is the type of transport wherein energy is required so as to pump molecules and ions across membranes against a concentration gradient. Exocytosis is considered an active transport mechanism because it describes the process of vesicles fusing with the plasma membrane and releasing their contents to the outside of the cell. This is an energy requiring process.

The process of exocytosis occurs when a cell produces substances which are meant to be exported, such as protein, or when the cell is getting rid of a waste product. Newly made membrane proteins and membrane lipids are moved on top the plasma membrane by exocytosis.