Time Line…… 150 years of Discovery

1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

a. Thomas Hunt Morgan shows that genes are located linearly along chromosomes
b. Oswald Avery, Colin MacLeod, and Maclyn McCarty show that DNA, and not protein, is the "transforming factor" Griffith first
identified
c. Gregory Mendel publishes his work on the heredity of peas
d. Alfred Hershey and Martha Chase show that viral DNA and not viral protein direct the replication of new viruses, confirming
that DNA is the molecule that mediates heredity.
e. Working with soiled bandages, Friedrich Miescher identifies DNA as an acidic substance in cell nuclei.
f. In an experiment with lab mice, Frederick Griffith transfers the deadly component of a strain of pneumonia bacteria to an
innocuous bacteria strain, and determines there must be a genetic "transforming factor" in the bacteria
g. Erwin Chargaff shows there are equal amounts of the nucleotides adenine (A) and thymine (T) as well as equal amounts of
guanine (G) and cytosine (C), i. e. there is an A for every T and a G for every C.
h. Werner Arber isolates restriction enzymes.
i. James Watson and Francis Crick describe the three-dimensional structure of DNA
J. First genetically engineered drug: Humulin, a kind of insulin grown in genetically modified bacteria is produced by the Eli
Lilly pharmaceutical company
k. Marshall Nirenberg, H. Gobind Khorana, Francis Crick, George Gamow, and other scientists crack the genetic code
l. Fred Sanger and others sequence DNA.
m. First successful gene therapy, performed on a girl with an inherited immune deficiency disorder.
n. PCR, to date the most accurate and sensitive method for amplifying DNA, is developed by Kary Mullis.
o. The first genetically engineered food is approved by the FDA.
p. Dolly the Sheep is the first mammal to be cloned.
q. Announcement of the final completion of the human genome sequence.