Mendel, Gregor | Research & Encyclopedia Articles

Botanist 1822-1884

Gregor Mendel, the father of genetics, was born on July 22, 1822, in Heinzendorf, Austria. He died on January 6, 1884. He was the first person to propose the idea of genes and to apply mathematics to genetics. Although his work was initially ignored by scientists, it proved to be the basis of modern genetics.

Mendel's interest in natural science developed early. He studied at the Philosophical Institute at Olmütz for two years. In 1843 he entered themonastery in Brünn, becoming a priest in 1847. Then he went to the University of Vienna, where he studied science from 1851 to 1853. In 1854 Mendel returned to Brünn and taught natural science in the technical high school there until 1868.

Seeking to learn how plants inherit different traits, Mendel began his experiments with garden peas in the small monastery garden in 1856. From 1856 to 1863 Mendel grew almost 30,000 specimens of garden peas. These plants had sharply contrasting characteristics (tall versus short, smooth seed versus wrinkled seed, and so on). He studied seven pairs of alternative characteristics, making hundreds of crosses by artificial pollination.

Mendel kept very careful records of the plants that he crossed and the resulting offspring. He noted that the occurrence of the alternative characteristics in the crossed varieties of plants followed simple statistical, mathematical laws. For example, Mendel crossed species that produced tall plants with those that produced short plants. Then, he counted the numbers of tall and short plants that appeared in subsequent generations. In the first generation, all of the plant offspring were tall. The next generation had some tall plants and some short plants in proportions of three (tall) to one (short). This showed that no blending of traits occurred (no medium-height plants). Further, if allowed to self-pollinate (fertilize themselves), the short plants always had short offspring. Mendel proposed that each plant received one character from each of its parents. Tallness was dominant and shortness was recessive, appearing only in later generations. Mendel also showed that when several pairs of alternative characteristics are observed, the several pairs enter into all possible combinations in the subsequent generations. In the pea plants he studied, he observed that the seven alternative characteristics recombined at random. He worked out the statistics of these combinations and confirmed his predictions by experiment.

Mendel developed three theories to explain the results of his experiments. His first law is the principle of segregation. It states that during the formation of sex cells (egg and sperm), paired factors are segregated (separated). Therefore, a sperm or egg may contain either a tallness factor or a shortness factor, but cannot contain both. The second law, the principle of independent assortment, states that characteristics are inherited independently of one another. Thus, the fact that the tallness factor is inherited does not determine which alternative of any other pair of characteristics is inherited. The law of dominance, which is the third theory, states that each inherited characteristic is determined by the interaction of two hereditary factors (now called genes). One factor always dominates the other (for example, tallness always dominates shortness). Mendel was the first to understand that trait units are physical particles passed from one generation to another by reproduction. This is remarkable, since at that time knowledge about cell structure was limited.

It is now known that Mendel's second principle applies only to genes that are transmitted in different linkage groups. Also, the appearance (or dominance) in hybrid offspring of one of the alternative characteristics has now been proven not to be true for all alternative characteristics. However, these limitations do not affect the fundamental truth of Mendel's findings. Mendel's system, called Mendelism, is one of the basic principles of biology.

Mendel presented his findings to his fellow scientists in 1865, but they failed to see the revolutionary nature of his work. When he was promoted to head of the monastery in Brünn in 1868, Mendel turned his focus away from science to concentrate on his duties at the monastery. He did, however, continue work in botany, bee culture, and the weather until his death.

Mendel was widely respected and loved, but went unrecognized as the great scientific thinker that he was. Fame and due credit came to Mendel only after his death. In 1900, three other European scientists independently obtained results similar to Mendel's. The researchers realized that he had already published both the experimental data laying out his results and a general theory explaining them nearly thirty-five years earlier.

Biological Evolution; Genes; Genetics.

The New Encyclopedia Britannica, 15th ed. Chicago: Encyclopedia Britannica, Inc., 1993.

The World Book Encyclopedia. Chicago: World Book, Inc., 1995.

The Year 2000 Grolier Multimedia Encyclopedia. Danbury, CT: Grolier Interactive Inc., 1999.

MendelWeb. University of Washington, Seattle. <http://www.netspace.org/MendelW eb/>.

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