Final answer:
Molecules must be packaged into vesicles before being exported from the cell through exocytosis, where the vesicle membrane fuses with the cell membrane to release the contents.
Step-by-step explanation:
Before the molecules are sent out of the cell in exocytosis, they must first be packaged into membrane-bound vesicles within the cell. These vesicles then move toward the plasma membrane, bind with it, and release their contents to the exterior of the cell. The vesicle membrane fuses with the cell membrane, effectively becoming part of it. This is a crucial step in processes such as the secretion of neurotransmitters at synapses between neurons, the release of digestive enzymes by the stomach and pancreas, and the secretion of hormones by endocrine cells.
In exocytosis, before the molecules are sent out of the cell, they must first fuse with and become part of the plasma membrane. Exocytosis is the process by which secretory vesicles release their contents to the cell's exterior. Vesicles containing substances move towards the plasma membrane and then meld with the membrane, ejecting their contents out of the cell.