Transmission-based precautions are for patients known to be infected or suspected to be infected or colonized with organisms that pose a significant risk to others. Some transmission-based precautions include contact, enteric, and droplet.
Contact Precautions:
Contact precautions are the measures taken to prevent the transmission of infectious agents, especially epidemiologically important microorganisms such as MRSA or influenza, primarily transmitted through direct or indirect contact with an...

Contact-dependent signaling, as the name suggests, requires that communicating cells be in direct contact with each other. This is achieved either through receptor-ligand interactions or by specialized cytoplasmic channels that allow the flow of small molecules between cells. In animal cells, channels called gap junctions facilitate contact-dependent signaling in certain tissues, whereas, plasmodesmata perform a similar function in plants.
Gap Junctions
In animal cells, gap junctions are formed...