The document describes research investigating the positive feedback loop of the AraC signaling system in E. coli. A synthetic gene circuit called ParaC-AraC was constructed containing the AraC gene and GFP reporter. Flow cytometry results showed the circuit exhibited bistable behavior, with GFP expression switching between low and high states depending on arabinose concentration between 2x10^-10 M and 2x10^-7 M. Future work will aim to further characterize the bistable behavior and investigate sequence mutations in the AraC gene.