Final answer:
DNA replication is the process in which the two sides of DNA separate and new matching nucleotides are added to fill in the gaps. The new set of nucleotides join together to form two DNA molecules.
Step-by-step explanation:
The process described in the question is DNA replication. During DNA replication, the double-stranded DNA molecule unwinds and separates into two single strands. Each single strand then serves as a template for the synthesis of a new complementary strand. The enzyme DNA polymerase reads the template strand and adds matching nucleotides to form a new strand of DNA.