1. Bacteria can control bioluminescence using quorum sensing. In bioluminescence, signaling molecules are secreted that bind to many cell surface receptors, turning on genes, including those that produce bioluminescence. (http://www.hhmi.org/biointeractive/bacterial-quorum-sensing). Gene expression occurs in bacteria such as V. fischeri when there is a high salt density. Another activity that bacteria controls using quorum sensing is mating. A tumefaciens is a bacteria that uses this horizontal DNA transfer to mate. Quorum sensing also allows bacteria to control sporulation. Sporulation occurs when bacteria are under stress and nutritional scarcity, and ends with a metabolically dormant endospore. When conditions improve in the environment, …show more content…
Multiple autoinducer signals help bacteria to use pieces of sensory information. Autoinducers are signaling molecules that aid in detection, production, and response. Using autoinducers, bacteria can tell when they should collectively alter gene expression. A growing population of cells will be able to synchronize their gene expression through the use of multiple autoinducer signals.
3. Vibrio harveyi is unique that it makes two autoinducers (1 and 2). Only V. harveyi makes autoinducer 1. A transmembrane domain receives signals from the two autoinducers and sends information inside the cell through a phosphorylation cascade. Through this cascade, an enzyme is made called “LuxCDABE.” This is responsible for inducing light in a high cell density environment or shutting off light in a low cell density environment.
4. Acyl homoserine lactone (AHL) quorum sensing enables a species to sense when it reaches a very high population density in its host. A protein called “LuxR” binds AHL molecules and regulates them when it is hit by a certain amount of AHL. Its DNA is exposed after binding to a molecule of an autoinducer. Both of these then bind to the promoters of genes. In this way, bacteria can communicate and express necessary genes for