Give a concise account on virulent cycle (or) Explain Lytic cycle of a phage.

Explanation

Lytic cycle: during lytic cycle of phage, disintegration of host bacterial cell occurs and the progegy virions are released. The Step involved in the lytic cycle are as follows:
(i) Adsorption : Phage T4 particle interacted with cell wall of host.,. The phage tail makes contact between the two, and tail fibres recognise the specific reciptor sites present on bacterial cell surface. The lipopolysaccharides of tail fibres acts as reciptor in phages. The process involving the recognization of phage two bacterium is called landing.once the contact is established between tale fibre of phahe and bacterial cell, tail fibre band to anchor the pins and base plate to the cell surface. This step is called pinning.
(ii) Penetration : the penetration process involves mechanical and enzymatic digestion of the cell wall of the host. At the recognization site phase digests certain cell wall structure by viral enzyme (lysozyme). After pinning the tail sheath contracts (using ATP) and appear shorter. After contraction of the base plate enlarge through which DNA is injected into the cell wall without using metabolic energy. The step involving injection of DNA particle alone into the bacterial cell is called transfection. The empty protein coat living outside the cell is known as 'ghost'.
(iii) Synthesis: this step involves the degradation of bacterial chromosome protein synthesis and DNA replication. The phage nucleic acid takes over the host biosynthetic machinery host DNA gets in activated and breaks down. Phage DNA suppresses the synthesis of bacterial protein and direct the metabolism of the cell to synthesis the proteins of the phage particles and simultaneously replication of phage DNA also takes place.
(iv) Assembly and maturation: the DNA of phage and protein coat are synthesized separately and assembled to from phase particles. The process of assembling the phage particles is known as maturation. After 20 minutes of infection about 300 new phages are assembled.
(v) release: the phage particle gets accumulated inside the host cell and are released the lysis of the host cell wall.