Which feature of the 16S rRNA gene makes it particularly useful for identifying bacteria across diverse taxa?

• A. It is found only in pathogenic bacteria
• B. It is encoded on plasmids
• C. It contains conserved regions for universal primers and hypervariable regions for differentiation
• D. It is identical across all bacteria

Answer: (C)

What makes 16S rRNA a versatile marker is its combination of conserved regions that allow universal primer binding and hypervariable regions that distinguish different bacteria. The conserved parts are similar across most bacteria, so you can design primers that amplify the gene from a wide range of species with a single PCR setup. Inside the same gene, the hypervariable regions vary between taxa, providing the sequence differences you need to tell one organism from another when you compare to reference databases. This pairing—shared primer sites for broad amplification and variable sequences for discrimination—is why 16S rRNA is so useful for identifying bacteria across diverse groups. It isn’t restricted to pathogens, it isn’t carried on plasmids, and it isn’t identical in all bacteria.