I'm a third-year medical student from Sweden.
I am attempting to simulate a specific chain of proteins in a cell using logic gates - specifically, I seek to construct a representation of the RTK-Ras-MAPK-pathway. In this pathway, there is a protein called Ras, which is important for regulating cellular proliferation, specialization and self-destruction.
Ras is interesting because it functions like a switch: it can be either on or off. When Ras is activated, it stays active for a short time and then automatically falls back to its off-state by intrinsic mechanisms.
I have read enough about logic gates to know that a gate cannot simply feed back into itself. What I would ideally like to do is something like below:
However, I've understood from several sources that this isn't feasible, and that connecting a gate to itself like this would create something of a "paradox"?
I've thought about using switch-controlled inputs from additional voltage sources as the second input for Ras (the XOR gate), but it seems to hinge on the fact that input 2 is undetermined until a signal comes from the XOR gate, and that the signal cannot be determined until the XOR gate gives some logical output.
My question is this: would it be possible to design a logic circuit that can take input from itself? If it isn't possible, are there ways to achieve similar results using other means?
Please note that I am not fluent in the language of electronics. If I have misunderstood something or am unclear I apologize.