Transduction is the transfer of bacterial genes by bacteriophages. In generalized transduction, which phage and which DNA is packaged in the phage head?

• A Only temperate phages; only lysogenic prophage DNA is packaged
• B Only lytic phages; only antibiotic resistance genes are selected for packaging
• C Only temperate phages; specifically, genes flanking the phage integration site are packaged via aberrant excision (specialized transduction)
• D Both lytic and temperate phages; any random fragment of bacterial chromosomal DNA (or plasmid DNA) of appropriate size can be mistakenly packaged during lytic assembly ✓

Explanation

In generalized transduction, during the lytic cycle, the packaging machinery occasionally mistakenly packages a fragment of bacterial chromosomal DNA (or plasmid DNA) instead of phage DNA into the phage head — any bacterial gene has an equal probability of being transduced (hence 'generalized'). The classic example is P1 phage in E. coli. In specialized transduction (e.g., lambda phage), only genes flanking the prophage integration site (attB — typically gal and bio operons for lambda) are transduced by aberrant excision. Both lytic and temperate phages can carry out generalized transduction.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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