To understand and compare DNA from different organisms, scientists in the American Museum of Natural History's Molecular Lab generally follow a three-step procedure. First, they isolate DNA to get a purified sample of DNA. Second, they use the polymerase chain reaction to amplify a small sequence of the DNA a million-fold. This provides enough copies of the small DNA sequence for researchers to perform the third step, sequencing and analyzing the small DNA sequence. Dr. Rob DeSalle narrates these three steps in the following videos.