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Gregor Mendel

2007 Schools Wikipedia Selection. Related subjects: Human Scientists

   CAPTION: Gregor Johann Mendel

      Born     July 20, 1822
               Heinzendorf, Silesia
      Died     January 6, 1884
               Brno, Moravia
      Field    Genetics
   Institution Abbey of St. Thomas in Brno
   Alma Mater  University of Vienna
    Known for  "Discovering" modern genetics
    Religion   Roman Catholic

   Gregor Johann Mendel ( July 20, 1822 – January 6, 1884) was an
   Augustinian abbot who is often called the "father of modern genetics"
   for his study of the inheritance of traits in pea plants. Mendel showed
   that the inheritance of traits follows particular laws, which were
   later named after him. The significance of Mendel's work was not
   recognized until the turn of the 20th century. Its rediscovery prompted
   the foundation of genetics.

Biography

   Mendel was born on July 20, 1822 to a German-speaking family in
   Heinzendorf, Silesia, then part of the Austrian Empire (now Hynčice in
   the Czech Republic), and was baptized 2 days later. During his
   childhood Mendel worked as a gardener, and as a young man attended the
   Philosophical Institute in Olmütz Olomouc. 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 1847 he was
   ordained as a priest. In 1851 he was sent to the University of Vienna
   to study, returning to his abbey in 1853 as a teacher, principally of
   physics.

   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. He commenced his study in his
   monastery's experimental garden. Between 1856 and 1863 Mendel
   cultivated and tested some 28,000 pea plants. His experiments brought
   forth two generalizations which later became known as Mendel's Laws of
   Inheritance.
   Johann- memorial plaque in Olomouc
   Enlarge
   Johann- memorial plaque in Olomouc

   Mendel read his paper, " Experiments on Plant Hybridization", at two
   meetings of the Natural History Society of Brünn in Moravia in 1865.
   When Mendel's paper was published in 1866 in Proceedings of the Natural
   History Society of Brunn, it had little impact and was cited about
   three times over the next thirty-five years.

   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.

   Mendel died on January 6, 1884, in Brünn ( Brno), Austria-Hungary (now
   Czech Republic), from chronic nephritis.

Rediscovery of Mendel's work

   Enlarge

   It was not until the early 20th century that the importance of his
   ideas was realized. In 1900, his work was rediscovered by Hugo de Vries
   and Carl Correns. Though Erich von Tschermak was originally also
   credited with rediscovery, this is no longer accepted as he did not
   understand Mendel's laws. Mendel's results were quickly replicated, and
   genetic linkage quickly worked out. Biologists flocked to the theory,
   as while it was not yet applicable to many phenomena, it sought to give
   a genotypic understanding of heredity which they felt was lacking in
   previous studies of heredity which focused on phenotypic approaches.
   Most prominent of these latter approaches was the biometric school of
   Karl Pearson and W.F.R. Weldon, which was based heavily on statistical
   studies of phenotype variation. The strongest opposition to this school
   came from William Bateson, who perhaps did the most in the early days
   of publicizing the benefits of Mendel's theory (the word "genetics",
   and much of the discipline's other terminology, originated with
   Bateson). This debate between the biometricians and the Mendelians was
   extremely vigorous in the first two decades of the twentieth century,
   with the biometricians claiming statistical and mathematical rigor,
   while the Mendelians claimed a better understanding of biology. In the
   end, the two approaches were combined as the modern synthesis of
   evolutionary biology, especially by work conducted by Ronald Fisher in
   1918.

   His experimental results have later been the object of considerable
   dispute. The renowned statistician R. A. 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. 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.

Mendel, Darwin and Galton

   Bust of Mendel at Mendel University of Agriculture and Forestry Brno,
   Czech Republic.
   Enlarge
   Bust of Mendel at Mendel University of Agriculture and Forestry Brno,
   Czech Republic.

   Mendel lived around the same time as the British naturalist Charles
   Darwin ( 1809 – 1882) and many have fantasized about a historical
   evolutionary synthesis of Darwinian natural selection and Mendelian
   genetics during their lifetimes. Mendel had read a German translation
   of Darwin's Origin (as evidenced by underlined passages in the copy in
   his monastery), after completing his experiments but before publishing
   his paper. Some passages in Mendel's paper are Darwinian in character,
   evidence that The Origin of Species influenced Mendel's writing. Darwin
   did not have a copy of Mendel's paper, but he did have a book by Focke
   with references to it. The leading expert in heredity at this time was
   Darwin's half-cousin Francis Galton who had mathematical skills that
   Darwin lacked and may have been able to understand the paper had he
   seen it. In any event, the modern evolutionary synthesis did not start
   until the 1920s, by which time statistics had become advanced enough to
   cope with genetics and evolution.

   The historian of evolution, Peter J. Bowler, has argued that it would
   not matter much if Darwin or even Galton had read Mendel, because not
   even Mendel was attempting to make the argument that his observed
   ratios were universal (he considered them to be a special case). In any
   case, Darwin and most of his contemporaries considered heredity to be a
   question best solved through observation of cell development—
   embryology in particular—and would not likely have been in a position
   to appreciate in-roads between evolution and what would become genetics
   (and indeed they were not appreciated until the early 20th century).

Possible Exception to his laws of Inheritance

   In 2005, scientists at Purdue University discovered in arabidopsis an
   alternative to previously known mechanisms of DNA repair, which one
   scientist called a "parallel path of inheritance". It was observed in
   mutations of the HOTHEAD gene. Plants mutant in this gene exhibit organ
   fusion, and pollen can germinate on all plant surfaces, not just the
   stigma. After spending over a year eliminating simpler explanations, it
   was indicated that the plants "cached" versions of their ancestors'
   genetic code going back at least four generations, and used these
   records as templates to correct the HOTHEAD mutation and other Single
   nucleotide polymorphisms. The initial hypothesis proposed that the
   record may be RNA-based Since then, alternative models have been
   proposed which would explain the phenotype without requiring a new
   model of inheritance More recently the whole phenomenon is being
   challenged as being a simple artifact of pollen contamination. "When
   Jacobsen took great pains to isolate the plants, he couldn't reproduce
   the [reversion] phenomenon," notes Steven Henikoff. In response to the
   new finding, Lolle and Pruitt agree that Peng et al.'s did observe
   cross-pollination but note that some of their own data, such as double
   reversions of both mutant genes to the regular form, cannot be
   explained by cross pollination.

Trivia

     * The lunar crater Mendel and asteroid 3313 Mendel were named in his
       honour.

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