quorum sensing GO:0009372 GO:0010699 GO:0060247 The cell-cell signaling process in which single-celled organisms carry out coordinated responses by monitoring their own population density, and often also that of other microbes, by producing small, diffusible, signal molecules, detecting the concentration of these molecules, and triggering a signal transduction pathway when a certain threshold is reached. Quorum sensing can occur amongst microbial communities in the environment or within host organisms. Wikipedia:Quorum_sensing biological_process cell-cell signaling involved in quorum sensing detection of cell density by secreted molecule quorum sensing system