T - even phages that attack the bacterium E . Coli cause lysis of the cells and are called virulent phages . They show lytic cycle . It involves `5` step process . They are 1. attachment 2. penetration 3. biosynthesis 4. maturation and 5. release .
Attachment :
1) Contact of the virion to the surface of host bacterium is called attachment or adsorption .
2) The phages use tail fibres for attachment to the complementary receptor sites on the bacterial cell wall .
2. Penetration :
1) The injection of phage nucleic acid into the host cell is called penetration .
2) The phage DNA is injected into the bacterium through the tail core like a hypodermal syrings .
3) The capsid remains outside the bacterial cell and is referred to as ghost .
3. Biosynthesis :
1) Once the phage DNA reaches the cytoplasm of the host cell, many copies of phage DNA, enzymes and capsid proteins are synthesized, using the cellular machinery of the host cell .
2) Host cell do not contain any complete infective viruses .
4. Maturation :
1) In this process bacteriophage DNA and capsids are assembled into complete virions .
2) This period of time between the infection by a virus and the appearance of the mature virus within the cell is called the eclipse period .
5. Release :
1) The final stage of viral multiplication is the lysis phase of the host cell and the release of virions from the host cell .
2) The plasma membrance of the host cell gets dissolved or lysed due to viral enzyme called lysozyme .
3) The bacterial cell wall breaks releasing the newly produced phage particles / virions .
