The deformation and fracture of graphene sheets containing 555-777 defects have been investigated by molecular dynamics simulations. Each such defect is a divacancy forming a localized configuration of three pentagonal and three septangular cells of carbon atoms in a hexagonal graphene lattice. An emphasis is made on the influence of 555-777 defects in graphene on its mechanical characteristics (stress-strain curve, uniaxial tensile strength, and maximum elastic strain).