A type of viral (phage) replication cycle resulting in the release of new phages by lysis (and death) of the host cell.

• A. Lysogeny
• B. Lytic
• C. Pseudolysis
• D. Lytic-lysogenic

Answer: (B)

The key idea is the lytic cycle, a virulent phage replication pathway that ends with the host cell bursting to release new phage particles. After the phage attaches and injects its DNA, the viral genome takes over the bacterial machinery to produce many copies of the genome and viral components. Those components are assembled inside the cell, and lytic enzymes such as holins and endolysins break down the bacterial cell wall, causing the cell to lyse and release a large number of new phages. This is in contrast to lysogeny, where the phage DNA integrates into the host genome and is copied along with the host without killing the cell, sometimes remaining dormant until induction. Pseudolysis and lytic-lysogenic describe other, less fitting scenarios: pseudolysis isn’t productive phage release, and lytic-lysogenic refers to temperate phages that can switch between cycles, not to a cycle that immediately causes lysis.