The T3 phage (also known as Bacteriophage T3) is a specific type of bacteriophage, which is a virus that infects and replicates within bacteria. The T3 phage is a member of the family Podoviridae and genus T7-like viruses.

The T3 phage possesses a complex and well-studied structure consisting of a head or capsid that contains the genetic material, a tail attached to the head, and tail fibers extending from the tail. This viral structure enables the T3 phage to specifically infect and inject its genetic material into certain strains of Escherichia coli (E. coli) bacteria.

Once the T3 phage infects a target E. coli bacterium, it employs a lytic life cycle, meaning it immediately begins to hijack the host's cellular machinery to produce multiple copies of itself. This leads to the eventual lysis or bursting of the infected bacterium, releasing new T3 phages into the surroundings to infect other bacterial cells.

The T3 phage possesses a linear double-stranded DNA genome, which encodes essential components for its replication, including enzymes responsible for genome replication and capsid formation. It also codes for proteins that can manipulate the host's metabolism, ensuring the provision of necessary resources for viral reproduction.

Due to its intricate structure and relatively small genome, the T3 phage has been extensively studied as a model organism in molecular biology and virology research. It has served as a valuable tool for understanding fundamental biological processes, such as DNA replication, transcription, and translation, as well as a model for investigating host-virus interactions and developing phage-based therapies against bacterial infections.