Biomedical Engineering Reference
In-Depth Information
Sequence mapping involves first breaking up the chromosome at random into large fragments, which
are then cloned with bacteria to make a bacterial artificial chromosome (BAC). These BACs are
ordered in such a way as to maximize the contiguous regions while using the minimum number of
BACs. Because BACs are too long to sequence, each one is broken at random into fragments that can
be handled by a sequencing machine—less than around 500 nucleotides—and each fragment is
sequenced. In this way the sequence of each BAC, and eventually of each contiguous region, are
defined. The result is a physical map that may have a few gaps between contiguous regions.
