Figure 1.

Sanger sequencing process. (A) Genome DNA is cut into different DNA fragments by ultrasound or enzyme, connected into a plasmid, and transformed into Escherichia coli. (B) The Dideoxy chain termination method is used for sequencing. The reaction system is a mixture of template, primer, DNA polymerase, and dNTPs. Four kinds of ddNTP (ddATP, ddTTP, ddCTP, and ddGTP) with radioisotope marks are, respectively, added to four reaction systems. If ddNTP is incorporated into the oligonucleotide chain, the 2′ and 3′ of ddNTP do not contain hydroxyl groups and cannot form phosphodiester bonds, then the extension of the DNA chain is terminated. (C) Four PCR reaction system products are added to gel electrophoresis, and autoradiography was used to determine the DNA sequence according to the location of electrophoresis.