1933
◊ Hybrid corn, developed by Henry Wallace in the 1920s, is commercialized.
Growing hybrid corn eliminates the option of saving seeds. The remarkable
yields outweigh the increased costs of annual seed purchases, and by 1945,
hybrid corn accounts for 78 percent of U.S.-grown corn.
1938
◊ The term molecular biology is coined.
1941
◊ The term genetic engineering is first used, by Danish microbiologist A. Jost in
a lecture on reproduction in yeast at the technical institute in Lwow, Poland.
1942
◊ The electron microscope is used to identify and characterize a
bacteriophage—a virus that infects bacteria.
◊ Penicillin mass-produced in microbes.
1944
◊ DNA is proven to carry genetic information—Avery et al.
◊ Waksman isolates streptomycin, an effective antibiotic for tuberculosis.
1946
◊ Discovery that genetic material from different viruses can be combined to
form a new type of virus, an example of genetic recombination.
◊ Recognizing the threat posed by loss of genetic diversity, the U.S. Congress
provides funds for systematic and extensive plant collection, preservation and
introduction.
1947
◊ McClintock discovers transposable elements, or "jumping genes," in corn.
1949
◊ Pauling shows that sickle cell anemia is a "molecular disease" resulting from a
mutation in the protein molecule hemoglobin.
1951
◊ Artificial insemination of livestock using frozen semen is accomplished.
1953
◊ The scientific journal Nature publishes James Watson and Francis Crick's
manuscript describing the double helical structure of DNA, which marks the
beginning of the modern era of genetics.
1955
◊ An enzyme involved in the synthesis of a nucleic acid is isolated for the first
time.
1956
◊ Kornberg discovers the enzyme DNA polymerase I, leading to an understand
ing of how DNA is replicated.
1958
◊ Sickle cell anemia is shown to occur due to a change of a single amino acid.
◊ DNA is made in a test tube for the first time.
1959
◊ Systemic fungicides are developed. The steps in protein biosynthesis are
delineated.
Also in the 1950s
◊ Discovery of interferons.
◊ First synthetic antibiotic.
1960
◊ Exploiting base pairing, hybrid DNA-RNA molecules are created.
◊ Messenger RNA is discovered.
1961
◊ USDA registers first biopesticide: Bacillus thuringiensis, or Bt.
1963
◊ New wheat varieties developed by Norman Borlaug increase yields by 70
percent.
1964
◊ The International Rice Research Institute in the Philippines starts the Green
Revolution with new strains of rice that double the yield of previous strains if
given sufficient fertilizer.
1965
◊ Harris and Watkins successfully fuse mouse and human cells.
1966
◊ The genetic code is cracked, demonstrating that a sequence of three
nucleotide bases (a codon) determines each of 20 amino acids. (Two more
amino acids have since been discovered.)
1967
◊ The first automatic protein sequencer is perfected.
1969
◊ An enzyme is synthesized in vitro for the first time.
1970
◊ Norman Borlaug receives the Nobel Peace Prize (see 1963).
◊ Discovery of restriction enzymes that cut and splice genetic material, opening
the way for gene cloning.
1971
◊ First complete synthesis of a gene.
1972
◊ The DNA composition of humans is discovered to be 99 percent similar to
that of chimpanzees and gorillas.
◊ Initial work with embryo transfer.
|
