Screening DNA

1859 Publication of Charles Darwin's The Origin of Species.

1865 Formulation of the Laws of Inheritance by Gregor Mendel.

1869 The DNA (deoxyribose nucleic acid) molecule first discovered by Frederick Miescher, who initially called it nuclein.

1880 Staining techniques developed which enable DNA to be observed in structures called chromosomes located in a cell's nucleus.

1899 First artificial insemination of eggs (sea urchin).

1907 First animal cells grown outside organisms, in cell culture.

1920 Genes shown to be arranged at specific locations along the chromosomes.

1930 X-rays shown to artificially increase mutation rate of genes.

1940 DNA confirmed as the molecule on which the genetic code resides.

1950 First X-ray photograph of DNA.

1952 First nuclear transplantation experiments (nucleus from undifferentiated cell into enucleated egg) on amphibians, laying the foundations for all future cloning work.

1953 James Watson and Francis Crick describe the molecular structure of DNA. This leads to an understanding of how the genetic code leads to protein synthesis.

1970 Restriction enzymes developed to cut DNA at specific locations, followed by other enzymes that provide the tools for genetic engineering.

1972 Synthesis of first molecules of recombinant DNA, that is DNA containing genetic material from another organism.

1973 First genetic modification of a bacteria.

1976 DNA testing first done for human genetic disease.

1977 First sperm bank opening, to sell sperm of "intellectually superior" donors, including Nobel Prize winners.

1978 Commercial genetic engineering begins. Manufacture of insulin using genetically modified (transgenic) bacteria in fermentation vats, followed by other human protein products.

1978 Birth of Louise Brown, the first "test-tube baby" born through in vitro fertilisation (IVF).

1980 First transgenic mammal (mouse) born.

1982 First complete DNA sequence of an organism (a virus) obtained.

1983 PCR (polymerase chain reaction) technique developed for amplifying very small samples of DNA. Revolutionises genetic research in many areas.

1983 First transgenic plant (tobacco) grown.

1984 Mammals (sheep) first cloned by transferring nuclei from undifferentiated embryo cells.

1985 Genetic fingerprinting techniques developed, a major advance in forsensic science.

1988 Human Genome Project set up, with aim of sequencing all the genes on the human genome.

1988 First living animal patented, a transgenic mice, which is sold commercially.

1993 Reported isolation of DNA from 135-million-year-old insect that has been preserved in amber.

1993 Genetically modified tomatoes first go on sale in USA.

1994 Start of clinical trials using gene therapy to treat cystic fibrosis.

1996 First large-scale plantings of transgenic crops (soybeans and maize) in the USA.

1996 Birth of first mammal (Dolly the sheep) cloned using nucleus from differentiated adult cell.

1997 Genetically modified food starting to be widely sold in Europe, although little of it labelled as such.

1998 First complete genome obtained for a complex organism (nematode).

1998 Korean scientists claim to have cloned a human embryo from an adult human cell.

2002 Human genome expected to have been sequenced.