Final answer:
DNA polymerase is the enzyme that synthesizes new DNA strands by adding complementary bases during DNA replication. It ensures the accurate copying of the original DNA sequence through a semi-conservative process, which includes proofreading and error correction.
Step-by-step explanation:
During DNA replication, an enzyme called DNA polymerase is responsible for creating a new DNA strand by adding complementary bases. This process occurs during the elongation stage where each of the original strands serve as templates. DNA polymerase systematically adds free nucleotides to the 3' end of the nascent DNA strand, ensuring the sequence is complementary to the template strand, following the base pairing rules where A pairs with T and G pairs with C.
DNA replication is semi-conservative, meaning each new DNA molecule consists of one original and one new strand. On the leading strand, the addition of nucleotides is continuous, whereas on the lagging strand, it occurs in segments called Okazaki fragments, which are later joined by DNA ligase. Through meticulous proofreading and error-correction processes, DNA polymerase ensures the new DNA is an accurate copy of the original.