Module section description: Signal transduction is a dynamic process by which signals are transmitted through the extra or intra cellular space. These signals can hold various information e.g. temperature, pH value, hormones, oxygen content or nutrient supply. After a signal was transduced a complex response of the biological system can be activated. This response systems enables the cell to adjust to the current conditions. Signal transduction is defined by signaling pathways or signal cascades. An example for signal transduction is the two-component system in prokaryotes or the MAPK cascades.