| 1) The
discovery in 1953 of the double helix, the twisted-ladder structure of
deoxyribonucleic acid (DNA), by James Watson and Francis Crick marked a
milestone in the history of science and gave rise to modern molecular
biology, which is largely concerned with understanding how genes
control the chemical processes within cells. In short order, their
discovery yielded ground-breaking insights into the genetic code and
protein synthesis. During the 1970s and 1980s, it helped to produce new
and powerful scientific techniques, specifically recombinant DNA
research, genetic engineering, rapid gene sequencing, and monoclonal
antibodies, techniques on which today's multi-billion dollar
biotechnology industry is founded. Major current advances in science,
namely genetic fingerprinting and modern forensics, the mapping of the
human genome, and the promise, yet unfulfilled, of gene therapy, all
have their origins in Watson and Crick's inspired work. The double
helix has not only reshaped biology, it has become a cultural icon,
represented in sculpture, visual art, jewelry, and toys. 2) Researchers working on DNA in the early 1950s used the term "gene" to mean the smallest unit of genetic information, but they did not know what a gene actually looked like structurally and chemically, or how it was copied, with very few errors, generation after generation. 3) Crick and Watson recognized, at an early stage in their careers, that gaining a detailed knowledge of the three-dimensional configuration of the gene was the central problem in molecular biology. 4) Other researchers had made important but seemingly unconnected findings about the composition of DNA; it fell to Watson and Crick to unify these disparate findings into a coherent theory of genetic transfer. 5) The time, then, was ripe for their discovery. 6) Watson and Crick published their findings in a one-page paper, with the understated title "A Structure for Deoxyribose Nucleic Acid," in the British scientific weekly Nature on April 25, 1953, illustrated with a schematic drawing of the double helix by Crick's wife, Odile. 7) The two had shown that in DNA, form is function: the double-stranded molecule could both produce exact copies of itself and carry genetic instructions. 8) Although recognized today as one of the seminal scientific papers of the twentieth century, Watson and Crick's original article in Nature was not frequently cited at first. Its true significance became apparent, and its circulation widened, only towards the end of the 1950s, when the structure of DNA they had proposed was shown to provide a mechanism for controlling protein synthesis, and when their conclusions were confirmed in the laboratory by Matthew Meselson, Arthur Kornberg, and others. |
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| 1) Mendel was born into a
German-speaking family in Heinzendorf, Austrian Silesia, then part of
the Austrian Empire (now Hynčice in the Czech Republic), and was
baptised two days later. During his childhood Mendel worked as a
gardener, and as a young man attended the Philosophical Institute in
Olomouc (Olmütz). In 1843 he entered the Augustinian Abbey of St.
Thomas in Brno, (Brünn). Born Johann Mendel, he took the name
Gregor upon entering monastic life. In 1851 he was sent to the
University of Vienna to study, returning to his abbey in 1853 as a
teacher, principally of physics. 2) Gregor Mendel, who is known as the "father of modern genetics", was inspired by both his professors at university and his colleagues at the monastery to study variation in plants, and he conducted his study the monastery's garden. 3) Mendel read his paper, "Experiments on Plant Hybridization", at two meetings of the Natural History Society of Brno in Moravia in 1865. 4) Elevated as abbot in 1868, his scientific work largely ended as Mendel became consumed with his increased administrative responsibilities, especially a dispute with the civil government over their attempt to impose special taxes on religious institutions. 5) At first Mendel's work was rejected (and it was not widely accepted until after he died). 6) It was not until the early 20th century that the importance of Mendel's ideas were realised. 7) His experimental results have later been the object of considerable dispute. Fisher analyzed the results of the F1 (first filial) ratio and found them to be implausibly close to the exact ratio of 3 to 1.[4] Only a few would accuse Mendel of scientific malpractice or call it a scientific fraud — reproduction of his experiments has demonstrated the accuracy of his hypothesis — however, the results have continued to be a mystery for many, though it is often cited as an example of confirmation bias. This might arise if he detected an approximate 3 to 1 ratio early in his experiments with a small sample size, and continued collecting more data until the results conformed more nearly to an exact ratio. It is sometimes suggested that he may have censored his results, and that his seven traits each occur on a separate chromosome pair, an extremely unlikely occurrence if they were chosen at random. In fact, the genes Mendel studied occurred in only four linkage groups, and only one gene pair (out of 21 possible) is close enough to show segregation distortion; this is not a pair that Mendel studied. The standard botanical author abbreviation Mendel is applied to species he described. |
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