Describe the lytic and lysogenic bacteriophage replication cycles

Question

What will be an ideal response?

Answer 1

Both lytic and lysogenic bacteriophage begin a replication cycle when contact is made with a suitable host bacterium. During attachment, components of the phage capsid bind to a specific molecule on the host bacterium. The bacteriophage genetic material is then injected into the bacterium, leaving the capsid on the outside. At this point, a lytic phage infection will result in the use of host cell factors to transcribe and translate viral genes. DNAases produced by the virus will break up the bacterial genome, and the viral genome is replicated. Once many copies of the viral genetic material and capsid proteins are produced, new phages are assembled by inserting the genome into the capsid. To release the bacteriophage, an enzyme called lysozyme breaks down the host cell wall. During a lysogenic infection, the phage DNA is not immediately replicated, transcribed, and translated, but instead, inserts itself into the bacterial genome. The phage DNA remains as a prophage and is copied whenever the host cell replicates its genome. The prophage is passed down the bacterium's daughter cells through binary fission. If the bacterial cell is ever under stress, the prophage may excise itself and begin a replication cycle identical to the remaining steps of the lytic cycle.