1. Bacteriophage

2. Outline Definition of Bacteriophage Structure of bacteriophage
Discovery of bacteriophage
Classification of bacteriophage
Replication of bacteriophage
References

3. Outline Definition of Bacteriophage Structure of bacteriophage
Discovery of bacteriophage
Classification of bacteriophage
Replication of bacteriophage
References

4. Definition of Bacteriophage
Bacteriophage, also known informally as a phage, is a virus that infects and replicates within Bacteria and Archaea. The term was derived from "bacteria" and the Greek φαγεῖν (phagein), "to devour".

5. Outline Definition of Bacteriophage Structure of bacteriophage
Discovery of bacteriophage
Classification of bacteriophage
Replication of bacteriophage
References

6. Structure of bacteriophage
Bacteriophage structures are diverse, but the vast majority of characterized phage share some common characteristics. Many phages have an icosahedral, head structure made of repeat protein subunits known as the capsid. This head structure contains the viral genome. The primary difference in phage are the presence or absence of a 'tail' structure.

7. Structure of bacteriophage

8. Outline Definition of Bacteriophage Structure of bacteriophage
Discovery of bacteriophage
Classification of bacteriophage
Replication of bacteriophage
References

9. Discovery of bacteriophage
Bacteriophage (bacterial viruses) were discovered by French- Canadian microbiologist Félix d'Hérelle, d'Hérelle was working at the Pasteur Institute in Paris, announced on 3 September 1917, that he had discovered "an invisible, antagonistic microbe of the dysentery bacillus".
Felix d’Herelle

10. Outline Definition of Bacteriophage Structure of bacteriophage
Discovery of bacteriophage
Classification of bacteriophage
Replication of bacteriophage
References

11. Classification of bacteriophage
All bacterial viruses are subdivided into 6 morphological groups from A TO F: A. phages composed of capsid and long tail with contractile sheath. B. phages composed of capsid and long tail with rigid sheath. C. phages composed of capsid and short tail.

12. Classification of bacteriophage
D. phages represented by grand-size nucleocapsid with fibrous or spiky surface structures. E. phages incorporating one nucleocapsid. F. rod-like or filamentous phages.

13. Classification of bacteriophage

14. Outline Definition of Bacteriophage Structure of bacteriophage
Discovery of bacteriophage
Classification of bacteriophage
Replication of bacteriophage
References

15. Replication of bacteriophage
Bacteriophage replicate by two mechanisms:
Lytic cycle
Lysogenic cycle

16. 1.Lytic cycle
In the lytic cycle, a phage acts like a typical virus: it hijacks its host cell and uses the cell's resources to make lots of new phages, causing the cell to lyse(burst) and die in the process.
The stages of the lytic cycle are:
1. Attachment: Proteins in the "tail" of the phage bind to a specific receptor (in this case, a sugar transporter) on the surface of the bacterial cell.
2. Entry: The phage injects its double-stranded DNA genome into the cytoplasm of the bacterium.

17. 1.Lytic cycle
3. DNA copying and protein synthesis: Phage DNA is copied, and phage genes are expressed to make proteins, such as capsid proteins.
4. Assembly of new phage: Capsids assemble from the capsid proteins and are stuffed with DNA to make lots of new phage particles.
5. Lysis: Late in the lytic cycle, the phage expresses genes for proteins that poke holes in the plasma membrane and cell wall. The holes let water flow in, making the cell expand and burst like an overfilled water balloon.

18. 1.Lytic cycle

19. 2.Lysogenic cycle
The lysogenic cycle allows a phage to reproduce without killing its host. In the lysogenic cycle, the first two steps (attachment and DNA injection) occur just as they do for the lytic cycle. However, once the phage DNA is inside the cell, it is not immediately copied or expressed to make proteins. Instead, it recombines with a particular region of the bacterial

20. 2.Lysogenic cycle

21. Outline Definition of Bacteriophage Structure of bacteriophage
Discovery of bacteriophage
Classification of bacteriophage
Replication of bacteriophage
References

22. References
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