Specialized vs. generalized transduction: In which form of transduction do transducing particles carry only specific portions of the bacterial genome?

Introduction / Context:
Transduction is bacteriophage-mediated gene transfer. Different modes (generalized vs. specialized) package bacterial DNA differently. Recognizing which carries specific adjacent genes is essential for mapping and understanding lysogenic conversion.

Given Data / Assumptions:

• Specialized transduction is associated with temperate phages that integrate at defined att sites.
• Generalized transduction can package random fragments of host DNA following lytic infection.
• Question asks which carries only specific portions of the bacterial genome.

Concept / Approach:

When a prophage excises imprecisely, it captures adjacent bacterial genes next to the integration site. Only those loci near the att site are transduced, hence “specialized.” In generalized transduction, headful packaging errors load random host DNA, not limited to a specific site.

Step-by-Step Solution:

Verification / Alternative check:

Lambda phage integrates at the gal–bio region in E. coli; faulty excision leads to transducing particles carrying only genes adjacent to the att site.

Why Other Options Are Wrong:

General transduction: random genome fragments.

Abortive: DNA persists transiently without full inheritance; not defined by “specific portions.”

“None” is invalid because a correct mode is known.

Common Pitfalls:

Confusing “generalized” with “specialized” due to wording; remember “specialized” equals “specific neighboring genes.”

Final Answer:

Specialized transduction