Which statement describes plasmid DNA?

Which statement describes plasmid DNA?

• A. It is small circular DNA used for cloning.
• B. It is the organism's entire chromosome.
• C. It is linear and part of the genome.
• D. It is only found in viruses.

Answer: (A)

Plasmid DNA are small circular DNA molecules that exist independently of the cell’s main chromosome and replicate on their own. This independence and circular form make them ideal carriers in cloning experiments, because scientists can insert a gene of interest into a plasmid and then introduce it into a host organism to propagate and study that gene. They are not the organism’s entire chromosome, which contains most of the organism’s genes, and plasmids are typically circular rather than linear. They are not exclusive to viruses; plasmids are common in bacteria (and some yeasts) as separate DNA elements that can carry useful features like antibiotic resistance or reporter genes.

Plasmid DNA are small circular DNA molecules that exist independently of the cell’s main chromosome and replicate on their own. This independence and circular form make them ideal carriers in cloning experiments, because scientists can insert a gene of interest into a plasmid and then introduce it into a host organism to propagate and study that gene. They are not the organism’s entire chromosome, which contains most of the organism’s genes, and plasmids are typically circular rather than linear. They are not exclusive to viruses; plasmids are common in bacteria (and some yeasts) as separate DNA elements that can carry useful features like antibiotic resistance or reporter genes.