First of all, an initiator protein unwinds a short amount of the double helix. Next, the protein known as helicase attaches to and then breaks the hydrogen bonds between the bases of the DNA strands, pulling them apart. As the helicase moves along the DNA molecule, it continues to break hydrogen bonds and also separate the two polynucleotide chains. Meanwhile, as the helicase separates the strands, another enzyme called primase briefly attaches to each strand and creates a place where replication can begin. This place is full of nucleotides, called primers. How are DNA strands replicated? At the beginning of the primer sequence, DNA polymerase attaches to the original DNA strand and begins to assemble a complementary strand. After the primer is placed on a single, unwound polynucleotide strand, DNA polymerase wraps itself around that strand and attaches new nucleotides to the exposed nucleobases. The polymerase assembles a new strand of DNA on top of the existing one. As DNA polymerase moves down the unwound DNA strand, it relies on the floating nucleotides surrounding the existing strand to build the new strand. The nucleotides that make up the new strand are paired with partner nucleotides in the template