What is the difference between draft sequence and finished sequence?
In generating the draft sequence (released in June 2000), scientists determined the order of base pairs in each chromosomal area at least 4 to 5 times (4x to 5x) to ensure data accuracy and to help with reassembling DNA fragments in their original order. This repeated sequencing is known as genome “depth of coverage.” Draft sequence data are mostly in the form of 10,000 base pair-sized fragments whose approximate chromosomal locations are known. To generate a high-quality reference sequence, completed in April 2003, additional sequencing was done to close gaps, reduce ambiguities, and allow for only a single error every 10,000 bases, the agreed-upon standard for the HGP. Investigators believe a high-quality sequence is critical for recognizing gene-regulatory components important in understanding human biology and disorders such as heart disease, cancer, and diabetes. The finished version provides an estimated 8x to 9x coverage of each chromosome.
