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Walter Sutton published “On the Morphology of the Chromosome Group in Brachystola magna”, hypothesizing that chromosomes carry the inheritance and that they occur in distinct pairs within a cell’s nucleus. Sutton also argued that how chromosomes act when sex cells divide was the basis for the Mendelian Law of Heredity.
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German embryologist Hans Spemann slip a 2-celled salamander embryo and each cell grew to adulthood, providing proof that early embryo cells carry necessary genetic information. This finally disproved Weismann’s 1885 theory that the amount of genetic information in cells decreases with each division.
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Hans Spemann published the results of his 1928 primitive nuclear transfer experiments involving salamander embryos in the book “Embryonic Development and Induction.” Spemann argued the next step for research should be the cloning organisms by extracting the nucleus of a differentiated cell and putting it into an enucleated egg.
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Oswald Avery found that a cell’s genetic information was carried in DNA.
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First animal cloning: Robert Briggs and Thomas J. King cloned northern leopard frogs.
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Francis Crick and James Watson, working at Cambridge’s Cavendish Labratory, discovered the structure of DNA.
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Biologist J.B.S. Haldane coined the term “clone” in a speech entitled “Biological Possibilities for the Human Species of the Next Ten-Thousand Years.”
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Marshall Nirenberg, Heinrich Matthaei, and Severo Ochoa broke the genetic code, discovering what codon sequences specified each of the twenty amino acids.
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DNA ligase, the enzyme responsible for binding strands of DNA, was isolated.
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James Shapiero and Johnathan Beckwith announced that they had isolated the first gene.
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Paul Berg combined the DNA of two different organisms, thus creating the first recombinant DNA molecules.
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Stanley Cohen and Herbert Boyer created the first recombinant DNA organism using recombinant DNA techniques pioneered by Paul Berg. Also known as gene splicing, this technique that allows scientists to manipulate the DNA of an organism - the basis of genetic engineering.
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Karl Illmensee and Peter Hoppe created mice with only a single parent.
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Baby Louise, the first child conceived through in vitro fertilization, was born
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Karl Illmensee claimed to have cloned three mice.
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In the case Diamond v. Chakrabarty, the United States Supreme Court ruled that “live, human made microorganism is patentable material.”
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Kary B. Mullis developed the polymerase chain reaction (PCR). This process allows for the rapid synthesis of designated fragments of DNA.
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The first human mother-to-mother embryo transfer was completed.
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Steen Willadsen cloned a sheep from embryo cells, the first verified example of mammal cloning using the process of nuclear transfer.
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Steen Willadsen used his cloning technique to duplicate prize cattle embryos.
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Ralph Brinster created the first transgenic livestock: pigs that produce human growth hormone.
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The National Institutes of Health officially launched the Human Genome Project to locate the 50,000 to 100,000 genes and sequence the estimated 3 billion nucleotides of the human genome.
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Human embryos were first cloned.
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Dolly, the first organism every to be cloned from adult cells, was born.
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Ian Wilmut and Keith Campbell, the scientists who created Dolly, also created Polly, a Poll Dorset lamb cloned from skin cells grown in a lab and genetically altered to contain a human gene.
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President Clinton proposed legislation to ban the cloning of humans for at least 5 years.
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Nineteen European nations signed a ban on human cloning.