A small ring of DNA independent from the bacterium's main genome that can be taken in and expressed by bacteria is called a(n) __________.

A small ring of DNA independent from the bacterium's main genome that can be taken in and expressed by bacteria is called a(n) __________.

• A. Plasmid
• B. Chromosome
• C. Mitochondrion
• D. Genome

Answer: (A)

A plasmid is a small, circular piece of DNA that exists independently of the bacterial chromosome and can be taken up by bacteria to express the genes it carries. Because it replicates on its own and can carry foreign genes, plasmids are widely used as cloning vectors to introduce new traits into bacteria without altering the essential core genome. In contrast, the bacterial chromosome contains the main genome with essential genes for survival, so it isn’t the separate, transferable ring described. Mitochondria are organelles found in eukaryotic cells, not bacteria, and the term genome refers to the entire set of genetic material, not a detachable plasmid. Thus, the described entity is a plasmid.

A plasmid is a small, circular piece of DNA that exists independently of the bacterial chromosome and can be taken up by bacteria to express the genes it carries. Because it replicates on its own and can carry foreign genes, plasmids are widely used as cloning vectors to introduce new traits into bacteria without altering the essential core genome. In contrast, the bacterial chromosome contains the main genome with essential genes for survival, so it isn’t the separate, transferable ring described. Mitochondria are organelles found in eukaryotic cells, not bacteria, and the term genome refers to the entire set of genetic material, not a detachable plasmid. Thus, the described entity is a plasmid.