DNA polymerase is best described as which of the following?

• A. Enzyme involved in DNA replication that joins individual nucleotides to their complementary base pair to produce a DNA molecule
• B. Enzyme that unwinds the DNA double helix
• C. Enzyme that cuts DNA at specific sequences
• D. Enzyme that splices RNA during processing

Answer: (A)

DNA polymerase is the enzyme that carries out DNA replication by adding nucleotides to a growing DNA strand, using the existing strand as a template and matching each incoming nucleotide to its complementary base. It forms the phosphodiester bonds that link nucleotides into a continuous DNA molecule and operates in the 5' to 3' direction, often with proofreading to keep replication accurate. The other activities listed belong to different enzymes: unwinding the double helix is done by helicase, cutting DNA at specific sequences is the role of restriction enzymes, and splicing RNA during processing is performed by the spliceosome.