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The CRISPR/Cas-based genome editing system has provided a powerful tool for control of gene activity within cells. Here, we model an experimentally plausible architecture harnessing the power of CRISPR/Cas to create a biomolecular bistable switch. The designed in vitro circuit is based on mutual repression of two genes together with two other activator genes. The repression is generated by the binding of catalytically dead endonuclease (dCas9) to the target gene mediated by a guide RNA. The activation is accomplished by use of an antiguide RNA partially complementary to the guide RNA. Using mathematical analysis of the model, we show that the proposed scheme is capable of exhibiting bistability. We further discuss ultrasensitivity of the regulatory modules, and their capacity to manage competition for dCas9 and downstream load.