  We show that topological Quillen homology of algebras and modules over
operads in symmetric spectra can be calculated by realizations of simplicial
bar constructions. Working with several model category structures, we give a
homotopical proof after showing that certain homotopy colimits in algebras and
modules over operads can be easily understood. A key result here, which lies at
the heart of this paper, is showing that the forgetful functor commutes with
certain homotopy colimits. We also prove analogous results for algebras and
modules over operads in unbounded chain complexes.
