Cell Connections and CommunicationAll living things communicate in one way or another. When you start looking at the world on a cellular level, you won't find communication in writing or words. Cellular communication is on a molecular level. This section talks about cells in a larger organism that are near each other. We don't cover the communication between single-celled organisms. They behave in different ways.
Gap JunctionsGap junctions are one type of cell connection. When two cells are right next to each other, their cell membranes may actually be touching. A gap junction is an opening from one cell to another. It's not a big opening, but it is large enough for cytoplasm to move from one cell to another. The connections are called channels and they act like tunnels for the movement of molecules.
DesmosomesDesmosomes are a second type of cell connection. They physically connect cells like the gap junction, but no opening is created. Proteins that bond the membrane of one cell to its neighbor create the desmosomes. You will find desmosomes in your skin cells. All of those proteins hold your skin together. The distance between the cells, however small, is about 10 times wider than the gap junction connections.
Tight JunctionThe last type of connection we will introduce is the tight junction. Tight junctions happen when two membranes actually bond into one. It makes a very strong barrier between two cells. Cells have some distance with a desmosome. Gap junctions allow molecules to pass. Tight junctions form solid walls. These types of connections are often found where one area needs to be protected from the contents of other areas.
Extracellular RNA (US-NIH Video)
Encyclopedia.com (Gap Junction):
Encyclopædia Britannica (Cell Junctions):