the tail. Cell walls are often locally digested by a virion-associated peptidoglycan hydrolase
and viral DNA enters the cytoplasm by as yet unknown mechanisms. In some cases DNA
entry is stepwise and transcription of the first DNA to enter is required for entry of the rest
of the DNA. Empty virions remain outside the infected bacterium, however most viruses
inject specific proteins with the DNA. Temperate viruses can, upon infection, either enter a
lytic growth cycle (above) or establish a lysogenic state (below). Physiological factors in the
cell can affect the decision between these two pathways.