Bacteria & Viruses & Archaea
Bacteria- An ubiquitous, single-celled microscopic organism in a spherical (cocci), rod-like (bacilli), or spiral shape
Bacteria can appear by itself or linked together in clusters (staph) or strands (strep).
Virus - an ultramicroscopic (20 to 300 nm in diameter), metabolically inert, infectious agent that replicates only within
the cells of living hosts, mainly bacteria, plants, and animals: composed of an RNA or DNA core, a protein coat, and, in
more complex types, a surrounding envelope.