This document describes the life cycles of bacteriophages and animal viruses. Bacteriophages follow either a lytic cycle involving attachment, penetration, biosynthesis, maturation and release, or a lysogenic cycle involving attachment, penetration and integration of viral DNA into the host genome. Animal virus life cycles involve attachment, penetration, uncoating, and biosynthesis leading to release, with DNA animal viruses and RNA viruses displaying similar processes and retroviruses inserting their RNA into the host genome.
