Which enzyme is primarily responsible for adding new nucleotides to a growing DNA strand during DNA replication?

• A. DNA polymerase
• B. Helicase
• C. Primase
• D. Ligase

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the process of DNA replication. DNA replication is the process by which a cell duplicates its DNA before cell division. It involves several enzymes working together to ensure the accurate copying of the DNA molecule.
2. Step 2: Identify the role of each enzyme listed in the options. Helicase unwinds the DNA double helix, Primase synthesizes RNA primers to initiate replication, DNA polymerase adds new nucleotides to the growing DNA strand, and Ligase seals gaps between DNA fragments.
3. Step 3: Focus on the specific task mentioned in the question: adding new nucleotides to a growing DNA strand. This task is performed by DNA polymerase, which matches complementary nucleotides to the template strand and catalyzes the formation of phosphodiester bonds.
4. Step 4: Recall that DNA polymerase requires a primer to begin adding nucleotides. Primase provides this primer by synthesizing a short RNA sequence complementary to the DNA template.
5. Step 5: Confirm that DNA polymerase is the enzyme responsible for elongating the DNA strand by adding nucleotides, making it the correct answer to the question.