Sangersekventeringen

Sanger sequencing, also known as chain termination sequencing, is a method developed by Frederick Sanger and his colleagues in the 1970s for determining the nucleotide sequence of DNA. This technique is widely used in molecular biology and genetics for its accuracy and efficiency. The process involves the use of a DNA polymerase enzyme, which synthesizes a new strand of DNA complementary to the template strand. However, the DNA polymerase used in Sanger sequencing is modified to incorporate a chain-terminating nucleotide analog, typically ddNTPs (deoxynucleotide triphosphates), which halt the elongation of the DNA strand at specific points.

The sequencing reaction is typically carried out in four separate tubes, each containing one of the four ddNTPs (ddATP, ddCTP, ddGTP, and ddTTP). These tubes are then combined and subjected to electrophoresis, which separates the DNA fragments based on their size. The resulting autoradiograph or fluorescent image shows a series of bands, each corresponding to a specific nucleotide in the sequence. By reading the sequence from the bottom of the gel to the top, researchers can determine the order of nucleotides in the DNA template.

Sanger sequencing has several advantages, including its ability to produce long, contiguous sequences and its compatibility with automated sequencing machines. However, it also has limitations, such as its relatively high cost and the need for relatively pure and large DNA templates. Despite these limitations, Sanger sequencing remains a cornerstone of modern molecular biology and genetics, providing essential data for various applications, including genetic research, diagnostic testing, and evolutionary studies.