The effect of tensile stress on the electronic properties of pristine graphene mono-sheet was investigated. We applied different stress factors in order to investigate the mechanical and electronic properties of graphene monolayer. As a consequence of the applied tensile stress, different patterns of ripples were created. Whereas, different rippling levels were significantly tuned the electronic properties of the graphene monolayer. For instance, the band gap of graphene monolayer dramatically increased with increasing the tensile stress factor. Moreover, the combined effect of applying tensile stress as well as bending the sheet significantly modified the band gap. However, applying more tensile stress induced a reverse behavior. We highly believe that, controlling local curvatures of graphene monolayer opens up opportunities for strain assisted tuning of local electronic structure such as band gap engineered devices.