Genetic Engineering Toolbox

Sanger Method


F. Sanger

Description and Procedure:

DNA fragments are cloned using the M13 virus. DNA of this bacteriophage is single stranded, simplifying the procedure. The purified DNA is divided into 4 test tubes. Each tube is unique, containing a few specially modified molecules of one of the four nitrogen bases - dideoxy-nucleotides. The test tubes also contain all the materials necessary to make complementary strands to the DNA in the M13 virus. Whenever a modified nucleotide is randomly added to a growing complementary strand polymerization ends. The result obtained from all four tubes is a series of strands with all possible lengths differing by only one nucleotide. Gel electrophoresis of the product creates a series of bands which can be used to reconstruct the base sequence in the target DNA fragment.

Click here to see a diagram of the Sanger Method.

Uses or Function:

Used to determine the sequence of nitrogen bases in a DNA fragment or gene.