7 The 100 Most Influential Inventors of All Time 7

developed a similar procedure using dideoxynucleotide
chain-terminating inhibitors. DNA was synthesized until
an inhibitor molecule was incorporated into the growing
DNA chain. Using four reactions, each with a different
inhibitor, sets of DNA fragments were generated ending
in every nucleotide. For example, in the A reaction, a series
of DNA fragments ending in A (adenine) was generated.
In the C reaction, a series of DNA fragments ending in C
(cytosine) was generated, and so on for G (guanine) and T
(thymine). When the four reactions were separated side
by side on a gel and an autoradiograph developed, the
sequence was read from the film. Sanger and his coworkers
used the dideoxy method to sequence human mitochondrial
DNA, the first human gene to be sequenced. For his con-
tributions to DNA sequencing methods, Sanger shared
the 1980 Nobel Prize for Chemistry. He retired in 1983.

Additional Honours

Sanger’s additional honours included election as a fellow
of the Royal Society (1954), being named a Commander of
the Order of the British Empire (1963), the Royal Society’s
Royal Medal (1969), the Royal Society’s Copley Medal
(1977), election to the Order of the Companions of
Honour (1981), and the Order of Merit (1986). In 1992 the
Wellcome Trust and the British Medical Research Council
established a genome research centre, honoring Sanger by
naming it the Wellcome Trust Sanger Institute.

Tom Kilburn

(b. Aug. 11, 1921, Dewsbury, Yorkshire, Eng.—d. Jan. 17, 2001,
Manchester)

T

om Kilburn was an English engineer and coinventor

of the first working computer memory. He also