MICRB316 Lecture 11: Lecture 11.doc
8 Mar 2014
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Document Summary
Just as bacteria use the presence of small effector molecules internally to regulate gene expression, so too do they use external small effector molecules to sense the presence of other bacterial cells to coordinately regulate genes. The concentration of this external signal correlates with cell growth & allows them to detect a certain cell density. The two component system remains as the way that bacteria have to sense what happens around them. Quorum a large group that behaves similarly. This quorum contains a certain number of bacteria required for cooperation to be beneficial. Quorum sensing (qs) represents a basic form of cell-to-cell signaling. But some cells have >1 system, suggesting that other genes besides census taking are regulated this way. >1 qs system most likely as a way of identity conformation. Qs is a sensor of: growth phase/development, census taking. This form of signaling likened to hormones; pheromones; quoromones; autoinducer; 2: g+ bacteria use oligopeptide signals signal via 2c phosphorelay.
