All are characteristics of molecular motors or motor proteins except: a. they must be able to associate and dissociate reversibly with a polymeric protein array, a surface or substructure in the cell. b. they use chemical energy (e. g., atp) to orchestrate movement. c. they transfer atp energy into mechanical energy. d. atp hydrolysis is presumed to drive and control protein conformational changes that result in sliding or walking movement of one molecule relative to another. e. all are true.