Bacteriophage

**Bacteriophage**

The Bacteriophage virus was discovered by microbiologists and Felix D Herelle.

What a Bacteriophage celldoes: A virus infects a bacterial cell by first attaching to the bacterial cell wall by its tail. In coliphages the tail is a complex protein structure consisting of a hollow contractile sheath, with a plate at the base that contains long protein fibers. The tail fibers fix the base plate to the specific receptor site on the bacterial cell wall, and the tail sheath contracts like a syringe, forcing the DNA that is inside the virus through the cell wall and cell membrane. The entire virus protein coat remains outside the bacterium. The injected nucleic acid is the viral genetic material; it makes use of the bacterium's chemical energy and biosynthetic machinery to produce viral enzymes, as well as more phage nucleic acid. The viral proteins and nucleic acid molecules within the bacterial host assemble spontaneously into up to a hundred new phage particles. Eventually the bacterium lyses, releasing the particles. Lysis can be readily observed in bacteria growing on a solid medium, where groups of lysed cells appear as clear areas, or plaques.

The Shape of the Bacteriophage: The shape and size of the bacteriophage T4 head are dependent on genes that determine the scaffolding core and the shell of the prohead. Mutants of the shell proteins affect mainly the head length. Two recently identified genes (genes 67 and 68) and one already known gene (gene 22), whose products are scaffold constituents, have been investigated. Different types of mutants were shown to strongly influence the proportion of aberrantly shaped particles. By model building, these shape variants could be represented as polyhedral bodies derived from icosahedra, through outgrowths along different polyhedral axes. The normal, prolate particle is obtained by elongation along a fivefold axis. The mutations of the three core genes (genes 67, 68, and 22) affect the width mainly by lateral outgrowths of the prolate particle, although small and large isometric particles are also found. Many of the aberrant particles are multitailed, suggesting a correlation between tail attachment sites and shape.

The Cure for Bacteriophage: There is no known cure for Bacteriophage at this point.

When the Bacteiophage was discovered: The Bacteriophage was first discovered in the biological world in modern times.