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Mendel: The first geneticist

Updated Thursday 3rd August 2006

Born in 1822, Johann Gregor Mendel, the founder of genetics, used experiments on peas to show that inheritance takes place by means of discrete particles. These later turned out to be genes.

Peas Copyrighted image Icon Copyright: BBC

In 1843, at the age of 21, Mendel became an Augustinian friar at a monastery in Czechoslovakia. Like many other young men at the time, he found security and an education at the monastery. He began experimenting with flowers in the monastery's gardens, trying to develop new colour variations. This led to his experiments in hybridisation.

But Mendel was not alone in his field. Ever since humans began domesticating plants and animals we have wondered how traits were passed from parent to offspring. One belief was that traits were stored as 'particles' in the parts of each parent's body and 'blended' in the offspring.

Mendel chose a common garden pea (Pisum) for his first experiments in hybridisation. When picking a plant to experiment on, Mendel was also concerned that they must "during the flowering period, be protected from the influence of all foreign pollen, or be easily capable of such protection accidental impregnation by foreign pollen could lead to the wrong conclusions".

In the process of experimenting, he ended up making 287 crosses between 70 different pure bred plants. Approximately 28,000 pea plants were used and this does not take into account the other species of plants he experimented on!

The following is an extract from the translation of Mendel’s original paper on genetics:

The selection of the plant group which shall serve for experiments of this kind must be made with all possible care if it be desired to avoid from the outset every risk of questionable results.

The experimental plants must necessarily:
Possess constant differentiating characteristics.
The hybrids of such plants must, during the flowering period, be protected from the influence of all foreign pollen, or be easily capable of such protection. The hybrids and their offspring should suffer no marked disturbance in their fertility in the successive generations.

Accidental impregnation by foreign pollen, if it occurred during the experiments and were not recognised, would lead to entirely erroneous conclusions. Reduced fertility or entire sterility of certain forms, such as occurs in the offspring of many hybrids, would render the experiments very difficult or entirely frustrate them. In order to discover the relations in which the hybrid forms stand towards each other and also towards their progenitors it appears to be necessary that all member of the series developed in each successive generations should be, without exception, subjected to observation.


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