Exocytosis

Definition

Exocytosis is a cellular process in which substances contained within vesicles are expelled from the cell into the extracellular environment. This process is essential for the secretion of many types of molecules, including hormones and neurotransmitters.

5 Must Know Facts For Your Next Test

1. Exocytosis is an active transport mechanism that requires energy in the form of ATP.
2. It involves the fusion of vesicle membranes with the plasma membrane, releasing their contents outside the cell.
3. Exocytosis plays a critical role in cell signaling and communication by secreting signaling molecules.
4. This process can be either constitutive (continuous) or regulated (triggered by specific signals).
5. Key proteins involved in exocytosis include SNAREs, which facilitate vesicle docking and fusion.

Review Questions

• What type of transport mechanism is exocytosis, and does it require energy?
• How do vesicles release their contents during exocytosis?
• What role do SNARE proteins play in exocytosis?

Related terms

Endocytosis:

A process where cells engulf external substances, enclosing them within a vesicle to bring them inside.

Vesicle: A small membrane-bound sac that transports substances within a cell.

SNARE Proteins:

Proteins involved in mediating the fusion of cellular membranes during processes like exocytosis and endocytosis.