Final answer:
Endocytosis is the process where cells internalize substances from their surroundings, and exocytosis is the process where cells export substances to the extracellular environment. Both are types of active transport mechanisms that cells use to exchange materials with their surroundings.
Step-by-step explanation:
In the process of endocytosis, cells take up dissolved substances from the extracellular compartment by forming a furrow into which the substance can enter. Endocytosis involves the opsonization of a receptor and its ligand in clathrin-coated vesicles, along with the inward budding of the plasma membrane, allowing the cell to capture substances from outside its membrane.
Conversely, when a cell needs to secrete its own products into the extracellular environment, exocytosis is occurring. This is a process where the cell exports material using vesicular transport. Membrane-bound vesicles within the cell, carrying substances to be expelled, fuse with the cell membrane, thereby releasing their contents into the extracellular space.
Both endocytosis and exocytosis are active transport processes in which cells interact with their environment, either by importing extracellular substances or by exporting intracellular substances to the outside of the cell.