In exocytosis, vesicles inside the cell carry substances to the cell membrane, where they fuse with the membrane and release the cargo outside. In endocytosis, molecules are brought into the cell by a vesicle in the cell membrane. In some processes, vesicles shuttle between exocytosis and endocytosis, including intermediate endosomes. Endocytosis is more specific when a receptor in the vesicle binds a specific molecule. Within cells, proteins guide vesicles to particular organelles.
Intercellular junctions join cells.
In animals they include tight junctions, desmosomes, and gap junctions. In plants they include a pectin layer and plasmodesmata. The cytoskeleton is a network of rods and tubes that provides cells with form, support, and the ability to move. Dynein causes adjacent microtubules to slide, which moves the overall structure. Microfilaments are solid and smaller than microtubules.