A bacteriograph is any of a group of viruses that infect specific bacteria, usually causing their disintegration or dissolution. They are made of an outer protein coat or
capsid
that encloses the genetic material. They inject their genetic material into the bacterium following
infection. When the
strain is
viruilent, all the
synthesis of the host's
DNA,
RNA and
proteins ceases. The
phage
genome is then used to direct the
synthesis of
phage
nucleic
acids and
proteins using the
host’s transcriptional and translational apparatus.
Bacteriophages were discovered independently by
Frederick W. Twort
in Great Britain
(1915) and
Félix d’Hérelle
in France (1917). The first phages studied were those designated type 1 to type 7. The Teven phages, T2, T4, and T6, were used as model systems for the study of virus multiplication. Alfred Day Hershey and Martha Chase used the T2 bacteriophage in a famous experiment in 1952.Soon after making their discovery, Twort and d’Hérelle began to use phages in treating human bacterial diseases such as bubonic plague and cholera.
Bacteriophages come in different sizes and shapes but most of them have the same basic features: a head or capsid and a tail. A bacteriophage’s head structure, regardless of its size or shape, is made up of one or more proteins which protectively coats the nucleic acid. Though there are some phages that don’t have a tail, most of them do have one attached to its head structure. It is a hollow tube through which the nucleic acid passes through when the bacteriophage infects a host cell.
http://www.biologyonline.org/dictionary/Bacteriophage
http://www.britannica.com/EBchecked/topic/48324/bacteriophage
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