Abstract
The recurrent 24 hours oscillations of biological activities which are generally called circadian rhythms are considered to be a mechanism allowing synchronisation of biological processes. The oscillations are generated by operation of special clock-like intra-cell devices comprising commonly transcription-translation processes as basis of measuring the time. The clock mechanism is controlled by two cooperating working out-of-phase negative feedback loops. Directly the oscillations are driven by steering signals changing the adjustment of feedback loops. They are created de novo in each cycle by complexation of synthesized proteins after their concentration reaches suitably high values. The complexes inhibit the protein synthesis in the own system while inducing it simultaneously in the cooperating one initiating in this way the next oscillation wave. The inhibition of protein synthesis is correlated with the degradation of already synthesizes molecules allowing the return to starting point of oscillation. The alignment of the proper phase of peripheral tissue cells clocks is maintained by the central brain clock � master clock.
©Jagiellonian University, Medical College, Kraków, Poland, 2012