A bacteriophage consists of two main parts i.e., head and
tail.
Head The head is in the form of bipyramidal hexagonal
prism. It consists of proteinaceous membrane enclosing a
core of viral DNA. The DNA is double-stranded.
Tail It is cylindrical. It has four components are
(i) a central core.
(ii) a protein sheath surrounding the core.
(iii) a sheath connected to head by a collar and at distal end
to a hexagonal basal plate.
(iv) pins at the corners of basal plate. Basal plate also bears
six long tail fibres which are the organs of attachment
to the bacterial surface.