Notes on Generalized vs Specialized Transduction

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Notes on Generalized vs Specialized Transduction:

How does specialized transduction occur?

With temperate phage; these insert themselves into the bacterial chromosome. It should be noted than transduction occurs as an excision error, not as a packaging error (that's for generalized transduction).

What is a virulent phage?

A virulent phage is a bacteriophage that infects bacteria and immediately lyses it, and repeats the process over and over again.

What is a temperate phage?

A temperate phage is a bacteriophage that infects bacteria, however, a temperate phage has good temperament, and it resides and replicates within the lysogenic bacterial cell, awaiting the command to lyse the cell.

What is generalized transduction?

• Involves virulent bacteriophages.

• Phage penetrates into the host and takes over the replication machinery.

• More phage capsids and enzymes are created.

• Bacterial DNA is repressed and destroyed.

• Sometimes, however, pieces of the original bacterial DNA remain and may become incorporated into the phage DNA i.e., into the phage capsid head, creating a "mutated" bacteriophage.

• The mutated bacteriophage then infect other bacteria.

• If this happens, chances are, the original bacterial piece will become incorporated into the phage DNA again.

• Furthermore, when this mutated bacteriophage infects bacteria, the infected bacteria has "superpowers" i.e., the new bacteria genetically different and is resistant to antibiotics.

• So, technically, the remaining bacteria are using the virulent bacteriophages to their advantage!

• This type of genetic transfer is more efficient than transformation.

• Eg., S. thypi, S. aureus, Y. enterocolitica, and V. cholerae.

What is specialized transduction?

• Involves temperate bacteriophages.

• Phage penetrates into the host and takes over the replication machinery.

• More phage capsids and enzymes are created.

• However, the bacterium is not destroyed; the phage just replicates and lives within the bacterium.

• The bacteriophages are then called prophages, and the bacteria are called lysogenic bacteria.

• The prophage temporarily resides with the lysogenic bacteria, and will eventually lyse the bacteria.

• In this process of phage replication, original bacterial DNA is incorporated within the phage DNA, and when this phage infects other bacteria, the original bacterial DNA segment (which may carry antibiotic capability) goes along with it.

• Eg., E. coli, and S. thypi.

What is a transposon?

A transposon can be visualized as a piece of DNA "with legs" that can get up and re-insert itself at another location within the same DNA. Transposons can carry genes for antibiotic resistance and virulence factors, and are very important in this aspect.

Additional Readings:

Basic Virology

1. Immune defences against viruses
2. Viral Hepatitis
3. DNA viruses
4. Positive-sense RNA viruses
5. Human Immunodeficiency Virus
6. Negative sense RNA viruses
7. Double stranded RNA Viruses
8. Viruses associated with cancer
9. Generalized vs specialized transduction
10. Hepatitis serologic markers
11. Bacterial vs viral infections
12. Human Immunodeficiency Virus (HIV) Infections and AIDS
13. Steps When Patient is Newly Diagnosed with HIV

Related Topics

1. Prenatal Infections

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