Microbiology and phycology - Lecture -04

Microbiology and Phytology Lecture:4

 Bacteriophage Lifecycle In this lecture, the focus will be on the bacteriophage lifecycle. The bacteriophage is a type of virus that infects bacteria. 

There are two main types of bacteriophage lifecycles: 

The lytic lifecycle and the lysogenic lifecycle.

The lytic lifecycle is characterized by the destruction of the host cell.

It consists of several steps:

1. Adsorption: During adsorption, the bacteriophage attaches to the surface of the bacterial cell. This attachment occurs through specific receptor sites on the bacterial cell wall.

2. Infection After adsorption, the bacteriophage injects its DNA into the host cell. This DNA takes control of the host cell's protein synthesizing machinery.

3. Formation of New Phage Particles Once inside the host cell, the bacteriophage replicates its DNA and produces new phage proteins. These proteins assemble to form new phage particles.

4. Assembly In the assembly step, the new phage particles come together to form complete bacteriophages.

5. Liberation Finally, the newly formed bacteriophages break free from the host cell, causing the destruction of the cell.

Lysogenic Lifecycle : The lysogenic lifecycle is different from the lytic lifecycle as it does not result in the destruction of the host cell. Instead, the bacteriophage's DNA integrates into the host cell's DNA and remains dormant for a period of time. 

During this time, the host cell continues to divide and multiply, carrying the bacteriophage's DNA.

Summary

• The lytic lifecycle of a bacteriophage involves the destruction of the host cell.

• The lysogenic lifecycle of a bacteriophage involves the integration of the bacteriophage's DNA into the host cell's DNA.

• The lytic lifecycle consists of adsorption, infection, formation of new phage particles, assembly, and liberation.

• The lysogenic lifecycle does not result in the destruction of the host cell