TECH By hannahflury Jan 1, 1958 DNA Replication found semi-conservative DNA replication is semi-conservative, as shown by Meselson and Stahl using equilibrium density gradient centrifugation. Jan 1, 1959 mRNA Messenger RNA is the intermediate between DNA and protein. Jan 1, 1966 Genetic Code Cracked The genetic code is cracked by a number of researchers (including Nirenberg, Matthaei, Leder, and Khorana) using RNA homopolymer and heteropolymer experiments as well as tRNA labeling experiments. Jan 1, 1970 Restriction Enzyme Purified The first restriction enzyme is purified by Hamilton Smith. Jan 1, 1972 Recombinant DNA Contructed Recombinant DNA is first constructed by Cohen and Boyer. Jan 1, 1977 DNA Sequencing Technology Developed DNA sequencing technology is developed by Fred Sanger. Feb 20, 1986 PCR Developed PCR is developed by Kary Mullis. Jan 1, 1990 Genome Projects Begin Genome projects are begun. The yeast genome is complete in 1996, and the C. elegans genome is done in 1998. Jan 1, 1990 DNA Microarrays Invented DNA microarrays are invented by Pat Brown and colleagues. Jan 1, 1990 Small Events DNA fingerprinting, gene therapy, and genetically modified foods come onto the scene. Jan 1, 1995 Genome Projects Accelerate Automated sequencing technology allows genome projects to accelerate. Jan 1, 1996 First Clone The first cloning of a mammal (Dolly the sheep) is performed by Ian Wilmut and colleagues, from the Roslin institute in Scotland. Feb 20, 2000 Genomes Complete The Drosophila genome is completed. The Arabidopsis genome is completed. The human genome is reported to be completed. Jan 1, 2001 Sequence of Human Genome Released The sequence of the human genome is released, and the "post-genomic era" officially begins. Jan 1, 2009 Controversy Controversies continue over human and animal cloning, research on stem cells, and genetic modification of crops.