Gregor Mendel (1843-1822) was a botanist trained in philosophy, physics and mathematics, who is credited with having discovered the mathematical basis of the genetic sciences, which is now called “Mendelism”.

Next we will see Gregor Mendel’s biography as well as his main contributions to modern genetics.

Biography of Gregor Mendel, father of genetics

Gregor Johann Mendel was born on July 20, 1822, in the rural community Heinzendorf bei Odrau, in the former Austrian Empire, now the Czech Republic. He was the son of peasants with few economic resources, so Mendel spent his childhood working as a cattleman, which later helped him to complete his higher education.

He studied at the philosophical institute in Olomouc, where he showed great skills in physics and mathematics . Despite his family’s desire to continue on the family farm, Gregor Mendel began his theological formation in 1843. This was influenced by the fact that his academic skills were soon recognized by the local priest. In 1847 he was ordained a priest and in 1851 he was sent to the University of Vienna to continue his studies.

He trained there under the guidance of the Austrian physicist Christian Doppler and the physicist-mathematician Andreas von Ettingshausen. He later studied the anatomy and physiology of plants, and specialized in the use of microscopes under the guidance of the botanist Franz Unger, who was an expert in cell theory and supported the development of a pre-Darwinian theory of evolution, which had an important influence on Mendel’s thesis.

Despite having lived at the same time as Darwin and having read some of his texts, there is no evidence of direct exchange between Mendel and Darwin and their teachers.

Mendel was soon motivated by research into nature , which led him to study different species of plants, but also the area of meteorology and different theories of evolution. Among other things he discovered that the different varieties of peas have particular intrinsic properties which, when mixed together, eventually produce new plant species as independent units.

His studies laid the foundation for the discovery of the hereditary activity of genes, chromosomes and cell division , which became known as Mendel’s laws. Gregor Mendel died on January 6, 1884 in Austria-Hungary, from a kidney disease. He was not aware that he had discovered a fundamental part of the development of classical genetics, as his knowledge was “rediscovered” years later by Dutch scientists.

Mendel’s Laws of Inheritance

Mendel’s laws of inheritance, also known as Mendelian inheritance, are derived from his research, conducted between 1856 and 1863. This botanist had cultivated about 28000 pea plants , which led him to make two generalizations about how genetic information is transmitted based on genotype expression.

His text “Experiments on plant hybridization” was rediscovered by Hugo de Vries, Carl Correns and Erich von Tschermak, who had experimented and reached the same conclusions as Mendel. In 1900, another scientist, Hugo Vires, pushed for the recognition of Mendel’s laws, while coining the words “genetics,” “gene” and “allele. We will now look at what each of these laws consists of.

1. Mendel’s First Law

It is also known as the law of segregation of independent characters, the law of equitable segregation or the law of allele disjunction. It describes the random migration of chromosomes during the meiosis phase called anaphase I .

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What this law proposed was that during the formation of the gametes (the reproductive cells of living beings), each of the forms that have the same gene is separated from its pair , to give shape to the final gamete. Thus, each gamete has an allele for each gene and downward variation is ensured.

2. Mendel’s Second Law

This law is also called the Law of Independent Character Transmission. Mendel discovered the random alignment of chromosome pairs during the phase of meiosis called metaphase I.

The second law says that different features of genes on different chromosomes are inherited independently of each other, so that the pattern of inheritance of one does not affect that of the others.

The conclusion is that genetic dominance results from the expression of the set of genes and hereditary factors that exist in the organism (the genotype), and not so much from their transmission. There is a controversy over whether the latter constitutes a third law, which precedes the others, and is known as the “Law of Uniformity of Hybrids of the First Generation Branch”.

Bibliographic references:

  • Garrigues, F. (2017). Mendel’s Laws: 3 commandments of genetics. Medical genetics blog. Retrieved October 16, 2018. Available at https://revistageneticamedica.com/blog/leyes-de-mendel/.
  • Gregor Mendel (2013). New World Encyclopedia. Retrieved October 16, 2018. Available at http://www.newworldencyclopedia.org/entry/Gregor_Mendel.
  • Gregor Mendel (2018). Famous Scientists. The Art of Genius. Retrieved October 16, 2018. Available at https://www.famousscientists.org/gregor-mendel/.
  • Olby, R. (2018). Gregor Mendel. Encyclopaedia Britannica. Retrieved October 16, 2018. Available at https://www.britannica.com/biography/Gregor-Mendel.