Milestones in the Discovery of Genetics: A Timeline, Schemes and Mind Maps of Law

Download Milestones in the Discovery of Genetics: A Timeline and more Schemes and Mind Maps Law in PDF only on Docsity! Genetic Timeline 1859 Discovery: Natural Selection Charles Darwin wrote “On the Origin of Species by Means of Natural Selection, or the Preservation of Favored Races in the Struggle for Life.” 1865 Discovery: Heredity Transmitted in Units Gregor Mendel’s experiments on peas demonstrate that heredity is transmitted in discrete units. The understanding that genes remain distinct entities even if the characteristics of parents appear to blend in their children explains how natural selection could work and provides support for Darwin’s proposal. 1869 Discovery: DNA Isolated Frederick Miescher isolates DNA from cells for the first time and calls it “nuclein”. 1879 Discovery: Mitosis Described Walter Flemming describes chromosome behavior during animal cell division. He stains chromosomes to observe them clearly and describes the whole process of mitosis in 1882. 1 Genetic Timeline 1900 Discovery: Rediscovery of Mendel’s work 1902 Botanists DeVries, Correns, and von Tschermak independently rediscover Mendel’s work while doing their own work on the laws of inheritance. The increased understanding of cells and chromosomes at this time allowed the placement of Mendel’s abstract ideas into a physical context. 1902 Discovery: Chromosome Theory of Inheritance Walter Sutton observes that the segregation of chromosomes during meiosis matched the segregation pattern of Mendel’s 1902 Discovery: Orderly Inheritance of Disease A British physician, Archibald Garrod, observes that the disease alkaptonuria is inherited according to Mendelian rules. This disease involves a recessive mutation, and was among the first conditions ascribed to a genetic cause. 1909 Discovery: The Word Gene is Coined Wilhelm Johannsen coins the word “gene” to describe the Mendelian unit of heredity. He also uses the terms genotype and phenotype to differentiate between the genetic traits of an individual and its outward appearance. 2 Genetic Timeline 1956 Discovery: Cause of Disease Traced to Alteration Vernon Ingram discovers that a specific chemical alteration in a hemoglobin protein is the cause of sickle cell disease. 1958 Discovery: Semiconservative Replication of DNA Matthew Meselson and Franklin Stahl demonstrate that DNA replicates semiconservatively: each strand from the parent DNA molecule ends up paired with a new strand from the daughter generation. 1959 Discovery: Chromosome Abnormalities Identified Jerome Lejeune and his colleagues discover that Down Syndrome is caused by trisomy 21. There are three copies, rather than two, of chromosome 21, and this extra chromosomal material interferes with normal development. 1961 Discovery: First Screen for Metabolic Defect in Newborns Robert Guthrie develops a method to test newborns for the metabolic defect, phenylketonuria (PKU). 1961 Discovery: mRNA Ferries Information 5 Sydney Brenner, François Jacob and Matthew Meselson discover that mRNA takes information from DNA in the nucleus to the protein-making machinery in the cytoplasm. Genetic Timeline 1966 Discovery: Genetic Code Cracked Marshall Nirenberg and others figure out the genetic code that allows nucleic acids with their 4 letter alphabet to determine the order of 20 kinds of amino acids in proteins. 1968 Discovery: First Restriction Enzyme Described 1972 Discovery: First recombinant DNA Scientists describe restriction nucleases, enzymes that recognize and cut specific short sequences of DNA. The resulting fragments can be used to analyze DNA, and these enzymes later became an important tool for mapping genomes. Scientists produce recombinant DNA molecules by joining DNA from different species and subsequently inserting the hybrid DNA into a host cell, often a bacterium. 1973 Discovery: First animal gene cloned Researchers fuse a segment of DNA containing a gene from the African clawed frog Xenopus with DNA from the bacterium E. coli and placed the resulting DNA back into an E. coli cell. There, the frog DNA was copied and the gene it contained directed the production of a specific frog protein. 6 Genetic Timeline 1975 Discovery: DNA Sequencing Two groups, Frederick Sanger and colleagues, and Alan Maxam and Walter Gilbert, both develop rapid DNA sequencing methods. The Sanger method is most commonly employed in the lab today, with colored dyes used to identify each of the four nucleic acids that make up DNA. 1976 Discovery: First Genetic Engineering Company 1 D 1 D Herbert Boyer founds Genentech. The company produces the first human proteinin a bacterium, and by 1982 markets the first recombinant DNA drug, human insulin.977 iscovery: Introns Discovered Richard Roberts’ and Phil Sharp’s labs show that eukaryotic genes contain many interruptions called introns. These non- coding regions do not directly specify the amino acids that make protein products. 981 iscovery: First Transgenic Mice and Fruit Flies Scientists successfully add stably inherited genes to laboratory animals. The resulting transgenic animals provide a new way to test the functions of genes. 7 Genetic Timeline 1991 Discovery: ESTs, Fragments of Genes An expressed-sequence tag (EST) an identified piece of a gene, is made by copying a portion of a messenger RNA (mRNA) molecule. As such, ESTs provide a way to focus on the “expressed” portion of the genome, which is less than one-tenth 1992 Discovery: Second-Generation Genetic Map of Human Genome 1 D 1 D A French team builds a low-resolution, microsatellite genetic map of the entire human genome. Each generation of the map helps geneticists more quickly locate disease genes on chromosomes.994 iscovery: FLAVR SAVR Tomato The Food And Drug Administration approves the sale of the first genetically modified food. 995 iscovery: Ban on Genetic Discrimination in the Workplace Protection under the American with Disabilities Act is extended to cover discrimination based on genetic information. 10 Genetic Timeline 1996 Discovery: Mouse Genetic Map Completed 1997 Discovery: E. coli Genome Sequenced The lab mouse is valuable for genetics research because humans and mice share almost all of their genes, and the genes on average are 85% identical. The mouse genetic increases the utility of mice as animal models for genetic disease in humans. map The complete sequence of the E. coli genome will help scientists learn even more about this extensively studied bacterium 1998 Discovery: M. tuberculosis Bacterium Sequenced Mycobacterium tuberculosis causes the chronic infectious disease tuberculosis. The sequencing of this bacterium is expected to help scientists develop new therapies to treat the disease. 1998 Discovery: Roundworm C. elegans Sequenced The first genome sequence of a multicellular organism, the round worm, Caenorhabditis elegans, is completed. 11 Genetic Timeline 1999 Discovery: Chromosome 22 Sequenced The first finished, full-length sequence of a human chromosome is produced. Chromosome 22 was chosen to be first because it is relatively small and had a highly detailed map already available. Such a map is necessary for the clone by clone sequencing approach. 2000 Discovery: Human Genome Working Draft Completed By the end of Spring 2000, HGP researchers sequence 90 percent of the human genome with 4-fold redundancy. This working draft sequence is estimated to be 99.9% accurate. 2002 Discovery: Mouse Genome Working Draft Assembled and Analyzed The Mouse Genome Sequencing Consortium publishes an assembled draft and comparative analysis of the mouse genome. This milestone was originally planned for 2003. 2002 Discovery: Rat Genome Working Draft Completed By Fall 2002, researchers sequence over 90% of the rat genome with over 5-fold redundancy. 12