DNA Sequencing and Its Types

Abstract

The term DNA sequencing encompasses biochemical methods for determining the order of nucleotide bases. Sequencing of nucleic acid provides information about all the genetic information stored in the genome in the form of four nitrogen containing bases- adenine (A), guanine (G), thymine (T) and cytosine (C). For sequencing of nucleic acids various methods are used; (1) The classical methods including Sanger’s chain termination method and Maxam-Gilbert chemical degradation method, (2) Automated sequencers based on Sanger method, (3) Next generation sequencing methods which includes 454 Pyrosequencing, Ion Torrent sequencing, SOLiD sequencing and Illumina sequencing method i.e., most widely used nowadays. The major application of gene sequencing lies in forensic, medical and molecular biology studies but in agriculture also plant genome mapping and sequencing has accelerated the crop improvement program.