Bacteriophage

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

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

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".

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

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.

Structure of bacteriophage

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

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

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

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.

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.

Classification of bacteriophage

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

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

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.

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.

1.Lytic cycle

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

2.Lysogenic cycle

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

References www.presentationszone.com www.Wikipedia.org www.khanacademy.org https://pdfs.semanticscholar.org www2.le.ac.uk