Final answer:
Cell signaling is an example where molecules on the surface of one cell are recognized by receptors on another cell, involving cell-surface receptors such as enzyme-linked, ion-channel-linked, and G-protein-linked receptors, which facilitate signal transduction without the ligand entering the cell.
Step-by-step explanation:
An example of molecules on the surface of one cell being recognized by receptors on an adjacent cell is cell signaling. This process involves cell-surface receptors which are membrane-anchored proteins that bind to external signaling molecules, known as ligands. These receptors include enzyme-linked receptors, ion channel-linked receptors, and G-protein-linked receptors. When a ligand binds to the receptor, it triggers a signal transduction pathway, where the extracellular signal is converted into an intracellular signal, ultimately producing a cellular response.
For example, during cell signaling, the hormone insulin can bind to its receptor on the surface of a liver cell, initiating a cascade of events inside the cell that leads to the uptake of glucose from the blood. This interaction does not require the ligand to enter the cell, distinguishing cell-surface receptor activation from processes where the external molecule is internalized, like in endocytosis.
Other terms like endocytosis, exocytosis, and cell adhesion are related to different cellular mechanisms. Endocytosis is the process where the cell engulfs materials from the outside environment. Exocytosis is the opposite, where materials are expelled out of the cell. Cell adhesion refers to cells sticking to each other or the extracellular matrix through special cell surface proteins.