Early DNA Sequencing

Two sequencing techniques were developed independently in the 1970s. The method developed by Fred Sanger used chemically altered 'dideoxy' bases to terminate newly synthesized DNA fragments at specific bases (either A, C, T, or G). These fragments are then size-separated, and the DNA sequence can be read. This animation from Cold Spring Harbor Laboratory's Dolan DNA Learning Center presents early DNA sequencing through a series of illustrations of the processes involved.