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Stanford microbiologist Charles Yanofsky establishes the co-linearity of gene and proteins. In other words, he demonstrates that the linear sequence of nucleotides constituting a gene corresponds precisely with the linear sequence of amino acids in a protein. In 1964, proteins have been sequenced, but it is not yet possible to isolate genes for sequencing. That breakthrough does not occur for another four years. In a race against three other laboratories to prove co-linearity without the benefit of specific nucleotide sequence data, Yanofsky’s team starts from the amino acid sequence of an E. coli enzyme. Next, available methods are employed to map genetic mutations in the E. coli gene known to code for the enzyme. The group then compares the mutation map with structural changes in the sequence of the enzyme. Yanofsky and company find that when distances between mutations on the gene map increase or decrease, so does the number of amino acids between structural alterations in the enzyme, in a manner consistent with co-linearity. The hypothesis is confirmed.