What is a plasmid?

What is a plasmid?

• A. Circular segments of extrachromosomal DNA
• B. Chromosomal DNA
• C. Messenger RNA
• D. Ribosomal RNA

Answer: (A)

Plasmids are small, circular DNA molecules that exist outside the main chromosome and replicate independently. They’re extrachromosomal, meaning they’re not part of the cell’s primary genome, and they often carry genes that provide advantages such as antibiotic resistance or special metabolic traits. This combination—circular, extra-genomic DNA that can replicate on its own—defines a plasmid. In contrast, chromosomal DNA is the primary genome, while messenger RNA and ribosomal RNA are RNA molecules, not DNA.

Plasmids are small, circular DNA molecules that exist outside the main chromosome and replicate independently. They’re extrachromosomal, meaning they’re not part of the cell’s primary genome, and they often carry genes that provide advantages such as antibiotic resistance or special metabolic traits. This combination—circular, extra-genomic DNA that can replicate on its own—defines a plasmid. In contrast, chromosomal DNA is the primary genome, while messenger RNA and ribosomal RNA are RNA molecules, not DNA.