Bacterial cells contain organelles and DNA that are immersed within the cytoplasm and surrounded by a cell wall. The cytoplasm, or protoplasm, of bacterial cells is where the functions for cell growth, metabolism, and replication are carried out. Viruses are not considered cells but exist as particles of nucleic acid (DNA or RNA) encased within a protein shell. Viruses do not have nuclei, organelles, or cytoplasm like bacterial cells do.