A common method used to introduce recombinant DNA (rDNA) into bacterial host cells is:

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

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the key terms related to gene transfer in bacteria. These include transformation, transduction, and conjugation, each representing a different mechanism by which bacteria can acquire new genetic material.
2. Step 2: Define transformation: it is the process by which bacteria take up free, naked DNA fragments from their environment and incorporate them into their own genome. This is a common method used in laboratories to introduce recombinant DNA into bacterial cells.
3. Step 3: Define transduction: this involves the transfer of DNA from one bacterium to another via bacteriophages (viruses that infect bacteria). It is a natural process but less commonly used for introducing recombinant DNA in lab settings.
4. Step 4: Define conjugation: this is a process where genetic material is transferred directly from one bacterial cell to another through cell-to-cell contact, often involving a pilus. It is a natural mechanism for gene transfer but not typically used for introducing recombinant DNA in controlled experiments.
5. Step 5: Conclude that transformation is the correct answer because it is the standard laboratory technique for introducing recombinant DNA into bacterial host cells, allowing the uptake and expression of new genetic material.