LandMark Shifts in Perspective
ca 400 B.C. Hippocrates provides the first explanation for heritarytraits (pangenesis -  seeds produced by all parts of the body aretransmitted to offspring at conception)
1761 Joseph Kolreuter starts first systematic studies of genetic crosseson different strains of tobacco - Blending Theory of Inheritance.
1859 Charles Darwin publishes "On the Origin of Species"
1860 Gregor Mendel starts to follows traits in Pea crosses - ParticulateMechanism of Herititary / Law of Segregation / Law of Independant Assortment.
1869 Friedrich Miescher discovers DNA
1870’s Walter Flemming observes mitosis in epithelial cells of salamanderlarvae (mitos = Greek for thread)
1880’s Weisman & Nageli champion idea of a substance within thecell that is responsible for the transmission of traits from parents tooffspring.
1883 Edouard van Beneden observes meiosis in gamete formation.
1884-5 Several scientists (including Oscar Hertwig; Eduard Strasburger; Walter Flemming) suggest that chromosomes are the carriers of genetic material.
1876/7 Hertwig & Fol observe sperm entering egg during fertilization
1900 Hugo de Vries; Carl Correns & Erich von Tschermak rediscover Mendels principles
1901 Thomas Montgomery observes chromosomal pairing
1902-3 Theodore Boveri & Walter Sutton independantly propose the Chromosomal Theory of Inheritance.
Archibald Garrod notes the first genetic disease
1905 Bateson & Punnett observe non-independant assortment
1908 Thomas Hunt Morgan showed relationship between a genetictrait (White eye) and inheritance of a sex chromosome in Drosophila (“Mapped”first gene).
G. H. Hardy & Wilheim Weinberg formulatre the Hardy-Weinberg Principle
1909 Janssens proposes that crossing-over involves a physical exchangeof material between homologous chromosomes.
1913 Alfred Sturtevant used frequency of crossing-over to produce the first genetic map Sturtevant  A.H.  J. Experimental Zool. 14:43-59 (1914
Morgan & Bridges describe gene dosage effects Morgan T.H.& Bridges C.B.  J. Experimental Zool.  15:429-466(1913)]
1919 Bridges observes two genes effecting a single trait Bridges C.B.J. Experimental Zool.  28:337-384 (1919)]
1927 Muller shows X-rays to be the first environmental agent knownto cause mutations
1928 Griffith observed the transfer of genetic material (transformation)from one bacterium to another
1931 Creighton & McClintock correlate crossing-over with the productionof new arrangements of alleles Creighton H.B. & McClintock B. P.N.A.S.(USA)  17:492-497   (1931)
1941 Beadle & Tatum show that a gene codes for a single protein.
1944 Avery MacLeod & McCarty show that DNA is the genetic material.
Early 1950’s Chargaff & Davidson show that the amounts of A = Tand G = C in DNA Chargraff E. & Davidson J.N.  Eds.  TheNucleic acids: Chemistry and Biology  pp307-368 Academic PressNew York
1951 McClintock identifies transposons in maize.
1952 Hershey & Chase show that bacteriophage T2 injects DNA intothe bacterial cytoplasm rather than protein.
1953 Watson & Crick propose the double helical structure for DNAbased on model building and Rosalind Franklins X-ray studies of DNA
1956 Gierer & Schramm show that tobacco mosaic virus uses RNA ratherthan DNA as its genetic material
1958 Messelson & Stahl demonstrate that DNA replicates semi-conservatively.
Kornberg demonstrates in vitro DNA synthesis Lehman et al.J. Biol. Chem.  233:163-170 (1958)
1961 The triplet nature of the genetic code is discovered and decipheredindependently by Nirenberg & Ochoa. Nirenberg & Matthei P.N.A.S.(USA) 47:1588-1602 (1961)
Messenger RNA is discovered by Sidney Brenner; Francois Jacob & Matthew Meselson
Jacob & Monad propose the operon model for gene regulation Pardeeet al.  J. Mol. Biol.  1:165 (1959)]
Late 1960’s Britten & Kohne perform renaturation studies revealingrepititive DNA
1962 Francois Chapeville test adapter hypothesis of tRNA function.
1970 Temin & Baltimore report the discovery of Reverse Transcriptasein retroviruses.
1972 First cloning experiment Jackson D.A. et al.  P.N.A.S. (USA) 69:2904-2909 (1972);  Lobban P.E. & Kaiser A.D.  J. Molec. Biol.78:453-471 (1973)
1974 Arthur Kornberg proposes model of nucleosomal structure. Markus Noll tests the idea and sees 200 bp repeat units of DNA.
1976 Retroviral oncogenes are identified as the causitive agents oftransformation.
Weintraub & Groudine measure chromatin changes during transcription WeintraubH. & Groudine M.  Science  193:848-856 (1976)
1977 DNA sequencing becomes possible. Maxam A.M & Gilbert W.  P.N.A.S. (USA) 74:560-564 (1977); Sanger F. et al.  P.N.A.S. (USA) 74:5463-5467  (1977); Sanger F. Nobel Lecture: Determination of Nucleotide sequences in DNA Bioscience Reports 1:3-18  (1980)
Sequence of first "organis" determined - phage fX174 - by Fred Sanger
1978 Interupted genes are discovered and splicing of their transcripts inferred by Leder and colleagues
1979 Cellular oncogenes are discovered by transfection.
1981 Catylytic activity of RNA is discovered.
Transgenic mice and flies are obtained by introducing new DNA intothe germline.
1991 First successful gene therapy performed on two girls with severe combined immunodeficiency by W. French Anderson and others.
1992 First entire chromasome is sequenced Oliver S.G. et al. Nature357:38-46(1992)
1994 Prion hypothesis Wickner
1995 First complete genome sequence of free-living organism FleischmannR.D. et al.  Science 269:496-512 (1995)
1996 Completion of the sequence of the first eukaryotic organism.
1997 Cloning of mature mammalian cells is achieved.