What are the steps of the lytic cycle?

What are the steps of the lytic cycle?

Lytic Cycle : Simply mean bursting or rupturing cycle , over and over



It is one of the cycles of

a bacteriophage (virus) in which their is a master-slave

relationship between the bacteriophage (master) and bacteria

(slave).Following are the steps of lytic cycle…1)

In this step, the bacteriophage, attaches

itself by its tail to the
cell wall
of bacterium

(plural-bacteria).2) Digestion:
In this step, the

bacteriophage contains an enzyme called
lysozyme, which digest

the cell wall of bacterium (plural-
Thus an

opening is formed in the bacterial cell wall.3)

The bacteriophage contracts and injects its

DNA through the
opening, inside the host (bacterium), while

the protein coat and
tail remain outside.4) Taking

Inside bacterial cell, the bacteriophage DNA

takes over the
biosynthetic machinery of the host

(bacterium), to synthesize its
own DNA and protein molecule.5)

The bacteriophage multiplies and increases its

form a lot of daughter bacteriophages ,

the daughter
bacteriophages exert pressure on the cell wall of

bacterium.6) Rupturing:
Finally, the bacterial

cell ruptures ( lysis occurs) due to all that pressure caused by daughter

bacteriophages and release the
daughter bacteriophages out,

which are now ready to attack a new
bacteria and start their lytic

cycle, all over

again.The Viral Life Cycle | Microbiology

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Lytic Cycle:

The word lytic simply means to break down.


One of the reproductive cycle of a bacteriophage virus ( the viruses which infect bacteria) that results in the death of the host bacteria is known as lytic cycle. The term lytic refers to the last stage of the cycle in which bacteria burst and releases the daughter phages which are produced.

Virulent virus:

Those bacteriophage viruses which only replicate through lytic cycle are known as virulent virus.

6 Stages of lytic cycle:

Lytic cycle is completed in the six main stages that are described below.

1 Attachment of bacteriophage virus:

In the first step of the lytic cycle the bacteriophage virus uses it’s tail fibers to attach to a specific receptor site on the outer surface of bacteria.

2 Injection of viral DNA:

In this step the sheath of the tail starts to contract and creates a hole in the membrane of the bacterial cell. Through this hole the DNA is injected into the bacteria and the empty capsid is left outside as a ghost.

3 Hydrolysis of Bacterial DNA:

In this step the DNA of bacteria is broken down by the DNA of the virus to take over the control of the bacterial cell.

4 Production of new phages:

In this step the metabolic machinery of the bacterial cell is now controlled by the DNA of virus which directs the cell to produce phage proteins and form nucleotides of phages from degraded molecule of DNA of bacteria.

5 Assemblage:

The second last stage involves the assemblage of components of virus.After the production of proteins and nucleotides all the parts assemble to produce a bacteriophage virus. Three separate sets of proteins assemble to make head, tail and tail fibers of the new bacteriophage virus.

6 Lysis of the bacterial cell:

When 100 to 200 bacteriophages are produced then these phages direct the production of an enzyme which is known as lysozyme. Lysozyme has the ability to digest the cell wall of bacteria. With damaged cell wall osmosis takes place the cell swells and finally bursts to release all the bacteriophages. This is the last step of the cycle. These bacteriophage viruses are now ready to infect other bacteria and replicate themselves.


Lytic cycle is a viral reproductive cycle in which the host bacterium cell dies. The DNA is injected in the bacterial cell which then control the activities of the cell to form new phages. These bacteriophage viruses then cause lysis of the bacterial cell and are released in the environment.