Q.Distinguish between the lytic cycle and the lysogenic cycle.

A bacteriophage begins infection the same way regardless of which cycle follows: it attaches to its host bacterium via its tail fibres and injects its nucleic acid into the cell, leaving its protein coat outside. In the lytic cycle, this injected DNA immediately takes over the host's machinery to replicate itself and manufacture new phage heads, tails and fibres, which self-assemble into complete new phage particles; the phage enzyme lysozyme then breaks down the host cell wall, causing lysis - the cell bursts, releasing the newly made phages (the number released per cell being the burst size). Phages that always follow this destructive route are called virulent phages, with the T-even phages (such as T4) as the standard example. …