In this paper we present a higher-order calculus inspired by biochemical systems, based on port graph rewriting and strategic rewriting. The first-citizens of this calculus are molecular graphs, molecular graph rewrite rules, and their interactions. Thanks to the intrinsically concurrent nature of rewriting, computations may take place wherever it is possible and in parallel. In a complementary way, strategic port graph rewriting takes into account control on computations by allowing to control rewrite rules application.