lysogenic

Meaning: In the lysogenic cycle, a temperate bacteriophage injects its genome, which usually integrates into the host chromosome as a prophage (in some phages it persists as a plasmid). The host copies the prophage with its own DNA at each division, so daughter cells inherit it. A viral repressor keeps the lytic genes off, so no new virions are made and the cell is not destroyed for the time being.

On the MCAT: Passages contrast the two cycles. Lytic: rapid replication, virion assembly, lysis, release. Lysogenic: latent, no lysis, viral genome passed vertically to daughter cells. Induction by stress such as UV light or DNA damage can inactivate the repressor, so the prophage excises and the cell enters the lytic cycle. Expect to predict that a lysogenized culture grows normally until induced, then lyses. Prophage genes can also give the host new traits, such as toxin production in some bacteria.

Common confusion: Lysogenic does not mean the virus is gone or permanently inactive. The viral DNA is still present and can re-enter the lytic cycle. Do not confuse lysogenic with lysis: the lysogenic cycle is the one without lysis, at least until induction.