T4 Bacteriophase under Electron Microscope

A bacteriophage is a virus which infects bacteria. In particular, the bacteriophage T4 is a virus which infects E.Coli, a bacteria that has been used extensively for molecular biology research. The bacteriophage T4 exemplifies the life cycle of viruses. It exists as an inactive virion until one of its extended 'legs' comes into contact with the surface of an E. Coli. Sensors on the ends of its 'legs' recognize binding sites on the surface of the host's cell, and this triggers the bacteriophage into action. The bacteriophage binds to the surface of the host, punctures the cell with its injection tube, and then injects its own genetic blueprint. This genetic information subverts the host cell's normal operation and sets the cell's biosynthetic machinery to work creating replicas of the virus. These newly created viruses escape from the cell and then float about dormant until one happens to come into contact with a new host cell.