Bacteriophage : Virus infection bacteria are known as bacteriophage. (a) These are obligate parasites that occur in soil, sewage water, fruits.
(b) The phage possesses a tail and a head. .
(c) The viral DNA is thread like ds (double standed) macromolecule.
(d) There are 4 segments of the tail.
(e) Bacteriophage are of two types : (i) Lytic and (ii) Lysogenic phoges e.g., phage (Lambda), T2 phage etc.