Here is a simplified close up of replication, showing what happens along one of the template DNA strands.
The two complementary DNA strands separate, and because each nucleotide can only pair with its complement, adenine with thymine and cytosine with guanine, each strand can be used as a template to build a new complementary strand, producing two DNA molecules. DNA Replication: An Overview In principle, copying DNA, a process called DNA replication, is very simple.
