To survive, living systems receive information from outside environment and adjust their own internal workings in response. This adjustment depends not only on processing a combination of environmental signal inputs, but on determining the system’s current state. In digital circuit theory, this operating mode is known as sequential logic whose outputs is a function of the present value of inputs and, more importantly, the sequence of past inputs.
Nowadays, synthetically engineered genetic circuits constructed with combinational logic can perform a wide variety of tasks, but are not able to store a “state” and change from one state to another, which has limited their widespread implementation. This year, Peking iGEM is developing a Computer Aided Design (CAD) method for automatically designing genetic sequential logic circuits. By doing this, we are going to build asynchronous genetic sequential logic circuits in which the state of the system can change in response to changing inputs, and synchronous circuits in which the state of the system changes at discrete time in response to an intercellular clock signal.
