Bioinformatics
Genomics and Post-Genomics
Chapter One
Genome sequencing
1.1 Automatic sequencing
The dideoxyribonucleotide method, developed during the early 1980s in
England, at the Cambridge University laboratory of Fred Sanger, is today universally
employed to sequence DNA fragments. It is based on the use of DNA
polymerase to elongate a single strand of DNA, starting from a primer, utilizing
another DNA strand as the template. The DNA polymerase elongates the
strand in the presence of four deoxyribonucleotide monomers (dATP, dTTP,
dGTP, and dCTP) and a dideoxyribonucleotide analog (ddNTP), which acts as
the chain terminator (Figure 1.1). Specific incorporation of the analog by DNA
polymerase yields a mixture of fragments that selectively terminate at positions
corresponding to each nucleotide (As, in the example below).
The principle of the dideoxyribonucleotide ('dideoxy') method is illustrated
in Figure 1.2. Four parallel reactions are carried out, one with each ddNTP, the
DNA fragments obtained being separated by electropho ... read full excerpt from Bioinformatics: Genomics and Post-Genomics ebook
