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How HGP
How it was accomplished
Government funding through the National Institutes of Health in the United
States, and the Sanger Institute in Great Britain, as well as numerous other
groups from around the world broke the genome into smaller pieces; approximately
150,000 base pairs in length. These pieces are called "bacterial artificial
chromosomes", or BACs, because they can be inserted into bacteria where they are
copied by the bacterial DNA replication machinery. Each of these pieces was then
sequenced separately as a small "shotgun" project and then assembled. The
larger, 150,000 base pair chunks were then stitched together to create
chromosomes. This is known as the "hierarchical shotgun" approach, because the
genome is first broken into relatively large chunks, which are then mapped to
chromosomes before being selected for sequencing. The whole-genome shotgun (WGS)
method is faster and cheaper, and by 2003 - thanks to the availability of
assembly algorithms - it had become the standard approach to sequencing most
mammalian genomes.
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