Flexi Says: In the human genome project, the genome was divided into smaller, manageable chunks approximately 150,000 base pairs long that overlapped a little on both ends. Each of these fragments of DNA was inserted inside the bacterial artificial chromosome where they cloned and fingerprinted. The fingerprints depict the location of fragments overlaps without knowing the actual sequence and these overlap bits serve as the guide to mark each fragment place in the corresponding genome. The cloned fragments were then sequenced by first breaking the fragments into small, overlapping pieces about 1000 base pairs long and then by using the technique of Sanger method, each piece was sequence letter by letter and the method is called hierarchical shotgun sequencing.
