Because a virus consists only of protein and a single type of nucleic acid and possesses no organelles, it cannot reproduce autonomously and must deliver its genome into a host cell to appropriate that cell's ATP, ribosomes, and molecular precursors. Once inside, replication proceeds by one of two mutually exclusive strategies: the lytic cycle, in which the viral genome immediately commandeers host machinery to mass-produce viral nucleic acid and capsid proteins that self-assemble until the accumulating progeny lyse the host and disperse; or the lysogenic cycle, in which the genome integrates into the host chromosome as a repressed provirus (prophage) and is passively copied with each host division until a trigger inactivates the repressor and the genome excises to enter the lytic pathway. The concept belongs to virology and microbial genetics, and it frames viral reproduction as a conditional strategic choice between immediate amplification and latent persistence, contingent on host availability and environmental conditions.
Because a virus consists only of protein and a single type of nucleic acid and possesses no organelles, it cannot reproduce autonomously and must deliver its genome into a host cell to appropriate th…