phages nucleic acid are specific for each phage. This penetration mechanism can involve electrochemical membrane potential, ATP molecules, enzymatic splitting of peptidoglycan layer, or all three of these factor can be vital for the penetration of the nucleic acid inside the bacterial cell. Studies have been done on the T2 bacteriophage (T4-like phage) mechanism of penetration and it has shown that the phage's tail does not penetrate inside the bacterial cell wall and penetration of this phage involves electrochemical membrane potential on the inner membrane. Replication and packaging Virus T4 genome is synthesized within the host cell using rolling circle replication. The time it takes for DNA replication in a living cell was measured as the rate of virus T4 DNA elongation in virus-infected E. coli. During the period of exponential DNA increase at 37 °C, the rate was 749 nucleotides per second. The mutation rate per base pair per replication during virus T4 DNA synthesis is 1.7 per 10−8, a highly accurate DNA copying mechanism, with only 1 error in 300 copies. The virus also codes for unique DNA repair mechanisms. The T4 phage head is assembled empty around a scaffolding protein, which is later degraded. Consequently, the DNA needs to enter the prohead through a tiny pore, which is achieved by a hexamer of gp17 interacting with DNA first, which also serves as a motor and nuclease. The T4 DNA packaging motor has been found to load DNA into virus capsids at a rate up to 2000 base pairs per second. The power involved, if scaled up in size, would be equivalent to that of an average automobile engine. Release The final step in viral reproduction and multiplication is determined by the release of virions from the host cell. The release of the virions occurs after the breakage of the bacterial plasma membrane. Nonenveloped viruses lyse the host cell which is characterized by viral proteins attacking the peptidoglycan or membrane. The lysis of the bacteria occurs when the capsids inside the cell release the enzyme lysozyme which break down the cell wall. The released bacteriophages infect other cells, and the viral multiplication cycle is repeated within those cells. Multiplicity reactivation Multiplicity reactivation (MR) is the process by which two or more virus genomes, each containing inactivating genome damage, can interact within an infected cell to form a viable virus genome. Salvador Luria, while studying UV irradiated virus T4