As scientists sought to understand more about the nature of inheritance of traits, hereditary processes were explained in ever increasing detail beginning at the populational level and going toward the molecular level. Keeping this fact in mind will help in understanding the timeline which follows.
| Year |
Scientist(s) |
Discovery |
| 1858 |
Charles Darwin Alfred Russel Wallace |
Joint announcement of the theory of natural selection-that members of a population who are better adapted to the environment survive and pass on their traits. |
| 1859 |
Charles Darwin |
Published The Origin of Species. |
| 1866 |
Gregor Mendel |
Published the results of his investigations of the inheritance of "factors" in pea plants. |
| 1900 |
Carl Correns Hugo de Vries Erich von Tschermak |
Mendel's principles were independently discovered and verified, marking the beginning of modern genetics. |
| 1902 |
Walter Sutton |
Pointed out the interrelationships between cytology and Mendelism, closing the gap between cell morphology and heredity. |
| 1905 |
Nettie Stevens Edmund Wilson |
Independently described the behavior of sex chromosomes-XX determines female; XY determines male. |
| 1908 |
Archibald Garrod |
Proposed that some human diseases are due to "inborn errors of metabolism" that result from the lack of a specific enzyme. |
| 1910 |
Thomas Hunt Morgan |
Proposed a theory of sex-linked inheritance for the first mutation discovered in the fruit fly, Drosophila, white eye. This was followed by the gene theory, including the principle of linkage. |
| 1927 |
Hermann J. Muller |
Used x-rays to cause artificial gene mutations in Drosophila. |
| 1928 |
Fred Griffith |
Proposed that some unknown "principle" had transformed the harmless R strain of Diplococcus to the virulent S strain. |
| 1931 |
Harriet B. Creighton
Barbara McClintock |
Demonstrated the cytological proof for crossing-over in maize. |
| 1941 |
George Beadle
Edward Tatum |
Irradiated the red bread mold, Neurospora, and proved that the gene produces its effect by regulating particular enzymes. |
| 1944 |
Oswald Avery
Colin MacLeod
Maclyn McCarty |
Reported that they had purified the transforming principle in Griffith's experiment and that it was DNA. |
| 1945 |
Max Delbruck |
Organized a phage course at Cold Spring Harbor Laboratory which was taught for 26 consecutive years. This course was the training ground of the first two generations of molecular biologists |
| late 1940s |
Barbara McClintock |
Developed the hypothesis of transposable elements to explain color variations in corn. |
| 1950 |
Erwin Chargaff |
Discovered a one-to-one ratio of adenine to thymine and guanine to cytosine in DNA samples from a variety of organisms. |
| 1951 |
Rosalind Franklin |
Obtained sharp X-ray diffraction photographs of DNA. |
| 1952 |
Martha Chase
Alfred Hershey |
Used phages in which the protein was labeled with 35S and the DNA with 32P for the final proof that DNA is the molecule of heredity. |
| 1953 |
Francis Crick
James Watson |
Solved the three-dimensional structure of the DNA molecule. |
| 1958 |
Matthew Meselson
Frank Stahl |
Used isotopes of nitrogen to prove the semiconservative replication of DNA. |
| 1958 |
Arthur Kornberg |
Purified DNA polymerase I from E. coli, the first enzyme that made DNA in a test tube. |
| 1966 |
Marshall Nirenberg
H. Gobind Khorana |
Led teams that cracked the genetic code- that triplet mRNA codons specify each of the twenty amino acids. |
| 1970 |
Hamilton Smith
Kent Wilcox |
Isolated the first restriction enzyme, HindII, that could cut DNA molecules within specific recognition sites. |
| 1972 |
Paul Berg
Herb Boyer |
Produced the first recombinant DNA molecules. |
| 1973 |
Joseph Sambrook |
Led the team at Cold Spring Harbor Laboratory that refined DNA electrophoresis by using agarose gel and staining with ethidium bromide. |
| 1973 |
Annie Chang
Stanley Cohen |
Showed that a recombinant DNA molecule can be maintained and replicated in E. coli. |
| 1975 |
|
International meeting at Asilomar, California urged the adoption of guidelines regulating recombinant DNA experimentation. |
| 1977 |
Fred Sanger |
Developed the chain termination (dideoxy) method for sequencing DNA. |
| 1977 |
|
The first genetic engineering company (Genentech) is founded, using recombinant DNA methods to make medically important drugs. |
| 1978 |
|
Somatostatin became the first human hormone produced using recombinant DNA technology. |
| 1981 |
|
Three independent research teams announced the discovery of human oncogenes (cancer genes). |
| 1983 |
James Gusella |
Used blood samples collected by Nancy Wexler and her co-workers to demonstrate that the Huntington's disease gene is on chromosome 4. |
| 1985 |
Kary B. Mullis |
Published a paper describing the polymerase chain reaction (PCR), the most sensitive assay for DNA yet devised. |
| 1988 |
|
The Human Genome Project began with the goal of determining the entire sequence of DNA composing human chromosomes. |
| 1989 |
Alec Jeffreys |
Coined the term DNA fingerprinting and was the first to use DNA polymorphisms in paternity, immigration, and murder cases. |
| 1989 |
Francis Collins
Lap-Chee Tsui |
Identified the gene coding for the cystic fibrosis transmembrane conductance regulator protein (CFTR) on chromosome 7 that, when mutant, causes cystic fibrosis. |
| 1990 |
|
First gene replacement therapy-T cells of a four-year old girl were exposed outside of her body to retroviruses containing an RNA copy of a normal ADA gene. This allowed her immune system to begin functioning. |
| 1993 |
|
FlavrSavr tomatoes, genetically engineered for longer shelf life, were marketed. |
Woodrow Wilson Index
