T2 phage

T2 phage is more properly called Enterobacteria phage T2. It is a virulent bacteriophage which infects "Escherichia coli" bacteria. 
It contains linear double-stranded DNA, and is covered by a protective protein coat. T2 is a 'tailed phage', one of a group known as the 'T4-like viruses'.
The DNA of the phage is injected into "E. coli" cells. It quickly turns the "E. coli" cell into a T2-producing factory. New phages are released when the cell ruptures. 
The Hershey–Chase experiments, done by Alfred Hershey and Martha Chase, showed how the DNA of viruses is injected into the bacterial cells, while most of the viral proteins stay outside. The injected DNA molecules cause the bacterial cells to produce more viral DNA and proteins. These discoveries showed that DNA, rather than proteins, is the hereditary material.