A Historical Timeline: Cracking the Code of Life

<<Previous | 1859-1902 | 1910-1962 | 1966-1978 | 1980-1988 | 1990-2003 | Next>>

1966
Marshall Nirenberg and colleagues crack the genetic code by demonstrating that a specific sequence of three nucleotide bases (a codon, or nucleotide "word") codes for, or specifies, each of the 20-some amino acids used by the cell to produce proteins.

Robert William Holley, an American biochemist, shows that transfer RNA is involved in the assembly of amino acids into proteins. In the process, Holley becomes the first person to determine the complete sequence of a nucleic acid.

1969
Scientists at Harvard Medical School are the first to isolate a single gene, a segment of bacterial DNA that assists in sugar metabolism.

Hamilton Smith discovers the first restriction enzyme, a kind of molecular "scissors" that cuts DNA at specific points, in Haemophilus influenzae bacteria.

1972
Paul Berg and colleagues combine DNA from different species and insert it into a host cell, creating the first recombinant DNA molecules.

1973
Stanley Cohen and Herbert Boyer "cut and paste" DNA from a frog into an E. coli cell where it is reproduced, marking the dawn of genetic engineering.

1974-1975
Allan Maxam and Walter Gilbert of Harvard University develop the method of DNA sequencing bearing their name. The Maxam-Gilbert method uses phosphorus labeling and four separate chemical reactions to determine the sequence of DNA nucleotides. At the same time, Frederick Sanger and colleagues at the Laboratory of Molecular Biology, Cambridge, England, develop the "chain termination" method of DNA sequencing, which becomes, with slight modifications, the standard sequencing method used today.

1975
Concerned about possible risks from genetic engineering, 150 molecular biologists meet at the Asilomar Conference Center in Pacific Grove, California, to discuss ways to control gentic research until its hazards are better understood. Their recommendations lead to years of government supervision of recombinant DNA research until it is determined to be safe.

Robert Holley determines the complete sequence of the RNA of a bacteriophage called MS2 (a phage is a parasitic virus that attacks bacteria).

1976
Genentech, the first company devoted to genetic engineering, is founded in South San Francisco by Herbert Boyer and Robert Swanson.

1977
Frederick Sanger in England determines the entire sequence of the bacteriophage OX174.

1978
The gene for human insulin is cloned.

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