Genetics

Biography of Gregor Johann Mendel and Mendels Laws of Heredity



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GREGOR JOHANN MENDEL (1822-1884) is widely regarded as the the "father of genetics".

He showed, through his experimental study of pea plants that the inheritance of traits followed specific laws. The significance of his work went unrecognised in his lifetime, but was rediscovered in the 1900s and became extremely influential. His laws formed the foundation for the new discipline of "genetics".

EARLY BACKGROUND AND EDUCATION

Johann Mendel was born July 20, 1822 in Heinzendorf, Austria (now Hyncice, Czech Republic) to a farming family. As a child, Mendel worked as a gardener and studied beekeeping, laying the seeds for his lifelong fascination with the mysteries of nature.

Mendel was sent to the Piarist school in Lipnik (Leipnik) in 1831. This was followed by grammar school at the age of 12 in Opava (Troppau). Mendel did very well in school, and furthered his studies at the Institute of Philosophy in Olomouc (Olmutz) in 1840.

BECOMING AN AUGUSTINIAN MONK

His family was not very well off, and could not afford to continue financing his studies, so upon the advice of one of his teachers, Mendel joined the Augustinian Abbey of St. Thomas in Brunn (now Brno, the Czech Republic) in 1843. That was when he took the name of Gregor.

The monastery proved fertile ground for Mendel to pursue his interests. The abbot at the time was very supportive of scientific education for the members of the monastery. And the Augustinians were active in education; the monks taught philosophy, foreign languages, mathematics, and natural sciences at secondary schools and universities. In addition to his theological studies, Mendel took courses in agriculture, pomiculture, and vine growing at the Institute of Philosophy in Brunn.

He was ordained into the priesthood in August of 1847, and served for a short time as vicar. However, it became clear that he was more suited to teaching; and in 1849, he was appointed a teacher of mathematics and Greek at the grammar school in Znojmo (Znaim).

UNIVERSITY OF VIENNA

In 1850, encouraged by the headmaster of the grammar school he was teaching at, he sat for a university examination. He failed, probably because he did not have a comprehensive university education. However, his written test on meteorology did impress the examiner enough to recommend to the monastery that Mendel be sent to the University of Vienna.

He studied at the university from 1851-1853, pursuing courses in physics, chemistry, mathematics, zoology and botany. It was there that he honed the experimental skills that he would use to develop his later theories.

On his return to Brunn in 1854, Mendel was appointed a teacher of physics and natural history in the Technical School. He taught until 1868, when he appointed abbot of the monastery.

MENDEL'S FAMOUS PEA EXPERIMENTS

Inspired by his university studies, and encouraged by his peers at the monastery, Mendel continued to pursue his love research at the monastery, conducted his experimental studies in its garden.

There is a story that out on a walk one day, he found an atypical variety of an ornamental plant. He re-planted it next to a typical variety. He found that the plants' offspring retained the essential traits of the parents. This observation is said to have provided the basis for Mendels' further experiments on heredity using pea plants.

Between 1856 and 1863, Mendel is estimated to have cultivated and tested some 29,000 pea plants. He painstakingly analysed traits such as height, colour and pod shape. He also carefully cross-pollinated the plants, noting what traits developed in the plants grown from the seeds.

MENDEL'S LAWS OF HEREDITY

The then widely accepted model of heredity predicted that the traits of the offspring would be a blend of parental traits. From his experimental studies, Mendel found that this model was wrong. He went on to formulate what is now known as Mendel's Laws of Heredity, consisting of the law of segregation (the first law), and the law of independent assortment (the second law)

Based on his observations, Mendel postulated the idea that traits are controlled by hereditary factors (what we now call genes). His first law, the law of segregation, explains that these factors occur in pairs which separate during the process of reproduction, so that in effect, each parent contributes only half its factors to the offspring. Or, put another way, the offspring gets half its factors from one parent, and half from the other. He further observed that these factors do not "blend" together. Instead, the offspring exhibit traits in exactly the same form as they appear in one or the other of its parents.

Mendel also made the discovery that some factors (which he termed "dominant") seem to consistently prevail over others (termed "recessive") in terms of the traits seen in the offspring.

Mendel's Second Law, the law of independent assortment, states that factors sort themselves independently of each other during the process of egg or sperm formation, and they combine again randomly in the offspring. Thus, different offspring of the same parents receive different sets of hereditary factors.

Mendel presented his findings at two meetings of the Natural History Society of Brunn in 1865. And his paper on the subject, "Experiments on Plant Hybridization", was published in 1866 in Proceedings of the Natural History Society of Brno. His work did not receive much attention, probably because it was published in a journal with limited circulation, and also because few scientists were focusing on this area of study at that time.

It was only in 1900 that his work was rediscovered by scientists studying similar phenomena. The importance of his work was quickly recognised, and his conclusions became the basis for the new science of heredity or "genetics".

OTHER RESEARCH INTERESTS

After his work with peas, he turned to experimenting with bees. He managed to produce a hybrid strain. However, he was not able to develop his ideas on heredity further because of the difficulties in controlling the mating behaviour of queen bees.

Mendel also worked on identifying and describing new plant species. The ones he described are denoted with the botanical author abbreviation "Mendel".

In addition to his interests in plants and heredity, he was also interested in meteorology. A member of the Agricultural Society in Brunn, Mendel summarised the results of meteorological observations and published these between 1862 and 1869. After that, he went on to publish three papers on storms in the period 1870 to 1872. He was a member of the Central Board of the Agricultural Society from 1870, and he supported the first weather forecasts for farmers in 1878.

MENDEL'S LATER YEARS

He scaled down his scientific work after he became abbot of his monastery in 1868. He was busy with administrative work. He was also embroiled in a dispute with the government who had imposed new taxes on religious institutions. To win him over to their side, the government appointed him to the Board of Directors of the Moravian Mortgage Bank (he became the vice-governor of the bank in 1876, and governor in 1881). Nevertheless, Mendel never agreed to the taxation law.

Mendel died from chronic nephritis on January 6, 1884 in Brunn.

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