"Lysis from within”
In this case, lysis of the host cell occurs as a result of phage replication. The genetic material is the only component of the virion that enters into the host cell, which may occur through injection (bacteriophages with contractile tails) or following the enzymatic breakage of the cell wall. In both cases, the pore generated in the membrane will affect its electric potential, although this harm is easily repaired. Once inside the cell, the genetic material of the bacteriophage is replicated hundreds of times, the coat proteins are synthesized and new particles are assembled that will constitute the viral progeny (usually between several tens and a few hundreds per infected cell). Release of the progeny is the consequence of the collaborative action of the holin, a hydrophobic polypeptide that forms pores in the cell membrane, through which the lysin (a muramidase) reaches the cell wall, thus provoking the lysis of the host-cell.
"Lysis from without"
In this case, lysis of the host cell occurs in the absence of phage replication. This happens when a sufficiently high number of phages particles adhere to the cell, and lyse it through alteration of the membrane electric potential, and/or the activity of cell wall degrading enzymes.
Lysogenic bacteriophages
Some dsDNA bacteriophages, however, have the capacity to synthesize a repressor protein that silences most bacteriophage genes and results in abortion of the lytic cycle. Under these circumstances the bacteriophage DNA (the prophage) synchronizes its replication to that of the host to be inherited by its offspring.
In most cases this is brought about through integration of the bacteriophage DNA into the host genome via site-specific recombination. This alternative method of bacteriophage propagation is called the lysogenic cycle and the bacteriophages able to pursue it are known as temperate.
