Biology Reference
In-Depth Information
Figure 7.6
Strategies for DNA sequencing of long DNA segments involve either directed (A) or ran-
dom (B) methods. Directed methods include walking, deletional sequencing, or transposon inser-
tion. Analyzing sequences from many contigs requires large-scale computer alignments.
sequencing must be redundant to ensure that the entire sequence has been
included in one or more subclones, and there is no way to identify specific frag-
ments. But, as you will discover soon, the shotgun approach has been adopted
widely due to innovations that allow assembly of the sequences into a contigu-
ous scaffold.
7.6 Sequencing DNA by the Polymerase Chain Reaction (PCR)
The
polymerase chain reaction
(PCR) is a procedure by which a specific segment
of DNA can be amplified by 1 million-fold, or more, using a DNA polymerase
(see Chapter 8). DNA fragments can be amplified by the PCR directly from
