Mendel, Johann Gregor (1822–1884)

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Date: 2007
Encyclopedia of World Scientists, Rev. ed.
Publisher: Facts On File
Series: Facts on File Science Library
Document Type: Biography
Pages: 1
Content Level: (Level 5)

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About this Person
Born: July 22, 1822 in Hyncice, Austria
Died: January 06, 1884 in Brünn, Austria-Hungary
Nationality: Austrian
Occupation: Botanist
Other Names: Mendel, Johann Gregor; Mendel, Gregor Johann
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Mendel, Johann Gregor (1822–1884)



Johann Gregor Mendel's pioneering plant hybridization experiments laid the foundation for the modern field of genetics. His careful analysis of research concerning the transmission of plant characteristics across generations provided the first mathematical basis for that science. His work led to the formulation of Mendel's laws of segregation and independent assortment and represented the first application of statistical analysis to the explanation of a biological phenomenon.

Mendel's intense interest in horticulture and plant hybridization was rooted in his childhood. Born on July 22, 1822, in Heinzendorf, Austria (now Hyncice in the Czech Republic), the young Mendel was raised helping his peasant farmer father, Anton, graft trees in the family orchard. Anton, who had served in the Napoleonic army, was dedicated to improving his crops by applying farming methods he had observed during his travels. Since the family lived on the border between German- and Czech-speaking regions, Mendel became fluent in both languages at an early age.

Mendel's parents and teachers noted his abilities and arranged for him to be educated at the Gymnasium in Troppau, where he studied from 1834 to 1840. After suffering a nervous breakdown brought on by stress, Mendel attended Olmütz University. In 1843 at the age of 21 he entered the Augustinian monastery in Brno. Although he felt he lacked a religious vocation, the monastery afforded him an excellent environment for his studies and freed him of financial worries. After a brief stint as a substitute teacher he failed to pass the teachers' qualifying exam. His order sent him to the University of Vienna from 1851 to 1853. In addition to learning botany and chemistry there, Mendel studied under Franz Unger, a plant physiologist who taught him how to organize botanical experiments. Mendel then returned to Brno but again failed the teachers' exam.

Although he continued to serve as a substitute teacher until 1868, Mendel's true work took place in the monastery's garden. From 1856 to 1863 he conducted a massive study involving 28,000 edible pea plants. He had noted several constant plant traits, including stem length (whether tall or short); flower position (whether axial or terminal); pod color (green or yellow); pod form (smooth or wrinkled); flower seed coat color (purple or white); and cotyledon color (yellow or green). He then crossed plants bearing these distinct attributes. The plants were self-pollinated and then individually wrapped to prevent pollination by insects. After collecting the seeds, Mendel scrupulously studied the offspring.

His findings overturned the accepted heredity theory of the day when he proved that the seven characters did not amalgamate on crossing: that is, rather than offspring bearing a blend of these characteristics, the progeny manifested only one such trait (for example, either a tall stem or short stem rather than some combination). However, when two of these “hybrid” progeny were crossed, the product of that union could manifest the traits of either grandparent, indicating that those elements had remained distinct, even when one was latent. This insight became known after 1900 as Mendel's first law, or the law of segregation. Another discovery was dubbed Mendel's second law, or the law of independent assortment. This principle holds that the various characters transmitted from parent to offspring combine randomly, rather than in any grouped bunch. Mendel's experiments revealed that a given pea plant was statistically no more likely to have a tall stem and smooth pod form, for example, than a tall stem and a wrinkled pod form. Moreover, all of the various permutations of the seven pea traits occurred with equal frequency.

Although Mendel presented his conclusions in 1865 at a meeting of the Natural Sciences Society and published his results in 1866, the significance of his experiments was lost on his contemporaries. After he was appointed abbot of his monastery, his bureaucratic duties expanded, leaving him less time for research. It was not until the 20th century that his work became widely recognized. Then not only did Mendel's experiments help forge the science of genetics but they also bolstered CHARLES ROBERT DARWIN's theory of evolution. Mendel's demonstration of the mechanism of variability in plant species buttressed Darwin's overarching theory of natural selection by supplanting Darwin's erroneous notion of pangenesis (the hypothetical theory that the reproductive egg or bud contains particles from all parts of the parent) as an explanatory principle.

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Gale Document Number: GALE|CX4065100612