Allows organisms to anticipate daily fluctuations in natural environment. This type of synchronization is called entrainment . Mechanisms that allow the clock to generate behavioral and physiological rhythms in a n organism.
Circadian clocks are cellular.
The minimal set of molecular causes and effects sufficient to describe circadian cycles as they might operate. Clock gene mutations disable the circadian clock. Some clock genes display circadian expression while some do not. The feedback loop is generated by a self-regulated oscillation of transciption and translation of clock genes. It displays a near 24 hour time constant.