ABSTRACT
In nature, most organisms copy their DNA in the same way. Polymerase chain reaction (PCR) mimics this process. Only it does it in a test tube. When any cell divides, enzymes called polymerases make a copy of the entire DNA in each chromosome. The rst step in this process is to “unzip” the two DNA chains of the double helix. As the two strands separate, DNA polymerase makes a copy using each strand as a template.
