Question

Transfer of a portion of DNA from one bacterium to another by a bacteriophage is called

• A. Transformation
• B. Conjugation
• C. Transduction
• D. Translocation

Hint:

Transformation -> Naked DNA.
Conjugation -> Contact Bridge.
Transduction -> Virus Phage.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
Bacterial genetics involves various mechanisms for horizontal gene transfer (HGT), which allows for genetic recombination without sexual reproduction.
The question asks to identify the specific mechanism where a virus (bacteriophage) acts as the carrier of genetic material.

Step 2: Detailed Explanation:

• Definition of Transduction: Transduction is the process by which DNA is transferred from one bacterium to another by a virus (bacteriophage).
It was first discovered by Norton Zinder and Joshua Lederberg in 1952 in Salmonella.

• Types of Transduction:
- Generalized Transduction: Occurs during the lytic cycle. A random fragment of bacterial DNA is accidentally packaged into a phage head.
- Specialized Transduction: Occurs during the lysogenic cycle. When a prophage excises itself from the bacterial chromosome, it may take adjacent bacterial genes with it.

• Comparison with other mechanisms:
- Transformation: The uptake of naked DNA from the surrounding environment.
- Conjugation: Transfer of DNA via direct cell-to-cell contact through a pilus.
- Translocation: This is a chromosomal mutation where a segment of DNA moves to a different location on the same or different chromosome, unrelated to HGT.

• Mechanism: When the "transducing phage" infects a new recipient cell, it injects the donor bacterial DNA. This DNA can then integrate into the recipient's genome via homologous recombination.

Step 3: Final Answer:
The correct term for viral-mediated DNA transfer is Transduction.