Biography of Mendel. Scientific activity of Gregor Mendel

The basic laws of heredity were described by the Czech monk Gregor Mendel more than a century ago, when he taught physics and natural history in high school Brünn (Brno).

Mendel was engaged in breeding peas, and it is to peas that we owe the scientific luck and rigor of Mendel’s experiments the discovery of the basic laws of heredity: the law of uniformity of first-generation hybrids, the law of segregation and the law of independent combination.

Some researchers distinguish not three, but two of Mendel's laws. At the same time, some scientists combine the first and second laws, believing that the first law is part of the second and describes the genotypes and phenotypes of the descendants of the first generation (F 1). Other researchers combine the second and third laws into one, believing that the “law of independent combination” is in essence the “law of independence of segregation” that occurs simultaneously in different pairs of alleles. However, in Russian literature We are talking about Mendel's three laws.

G. Mendel was not a pioneer in the field of studying the results of plant crossings. Such experiments were carried out before him, with the only difference being that plants were crossed different types. The descendants of such a cross (generation F 1) were sterile, and, therefore, fertilization and development of second generation hybrids (when describing breeding experiments, the second generation is designated F 2) did not occur. Another feature of Domendel's work was that most of the traits studied in different crossing experiments were complex both in terms of the type of inheritance and in terms of their phenotypic expression. Mendel's genius lay in the fact that in his experiments he did not repeat the mistakes of his predecessors. As the English researcher S. Auerbach wrote, “the success of Mendel’s work in comparison with the research of his predecessors is explained by the fact that he possessed two essential qualities necessary for a scientist: the ability to ask nature the right question and the ability to correctly interpret nature’s answer.” First, Mendel used different varieties of ornamental peas within the same genus Pisum as experimental plants. Therefore, the plants that developed as a result of such crossings were capable of reproduction. Secondly, as experimental traits, Mendel chose simple qualitative traits of the “either/or” type (for example, the skin of a pea can be either smooth or wrinkled), which, as it later turned out, are controlled by a single gene. Third, Mendel's real success was that the traits he chose were controlled by genes that contained truly dominant alleles. And finally, intuition prompted Mendel that all categories of seeds of all hybrid generations should be accurately counted, down to the last pea, without limiting ourselves to general statements summing up only the most characteristic results (say, there are more such and such seeds than such and such).

Mendel experimented with 22 varieties of peas that differed from each other in 7 characteristics (color, seed texture, etc.). Mendel carried out his work for eight years and studied 20,000 pea plants. All the pea forms he examined were representatives of pure lines; the results of crossing such plants with each other were always the same. Mendel presented the results of his work in an article in 1865, which became the cornerstone of genetics. It is difficult to say what deserves more admiration in him and his work - the rigor of his experiments, the clarity of his presentation of the results, his perfect knowledge of the experimental material, or his knowledge of the work of his predecessors.

In 1863, Mendel completed his experiments and in 1865, at two meetings of the Brunn Society of Natural Scientists, he reported the results of his work. In 1866, his article “Experiments on plant hybrids” was published in the proceedings of the society, which laid the foundations of genetics as an independent science. This is a rare case in the history of knowledge when one article marks the birth of a new one. scientific discipline. Why is it considered this way?

Work on plant hybridization and the study of the inheritance of traits in the offspring of hybrids was carried out decades before Mendel in different countries both breeders and botanists. Facts of dominance, splitting and combination of characters were noticed and described, especially in the experiments of the French botanist C. Nodin. Even Darwin, crossing varieties of snapdragons that differed in flower structure, obtained in the second generation a ratio of forms close to the well-known Mendelian split of 3:1, but saw in this only “the capricious play of the forces of heredity.” The diversity of plant species and forms taken into experiments increased the number of statements, but decreased their validity. The meaning or “soul of facts” (Henri Poincaré’s expression) remained vague until Mendel.

Completely different consequences followed from Mendel’s seven-year work, which rightfully constitutes the foundation of genetics. Firstly, he created scientific principles for the description and study of hybrids and their offspring (which forms to cross, how to conduct analysis in the first and second generations). Mendel developed and applied an algebraic system of symbols and character notations, which represented an important conceptual innovation. Secondly, Mendel formulated two basic principles, or laws of inheritance of traits over generations, that allow predictions to be made. Finally, Mendel implicitly expressed the idea of ​​discreteness and binarity of hereditary inclinations: each trait is controlled by a maternal and paternal pair of inclinations (or genes, as they later came to be called), which are transmitted to hybrids through parental reproductive cells and do not disappear anywhere. The makings of characters do not influence each other, but diverge during the formation of germ cells and are then freely combined in descendants (laws of splitting and combining characters). The pairing of inclinations, the pairing of chromosomes, the double helix of DNA - this is the logical consequence and the main path of development of genetics of the twentieth century based on the ideas of Mendel.

The name of the new science – genetics (Latin “relating to origin, birth”) – was proposed in 1906 by the English scientist W. Bateson. The Dane V. Johannsen in 1909 established in the biological literature such fundamentally important concepts as gene (Greek “genus, birth, origin”), genotype and phenotype. At this stage in the history of genetics, the Mendelian, essentially speculative, concept of the gene as a material unit of heredity, responsible for the transmission of individual characteristics in a number of generations of organisms, was accepted and further developed. At the same time, the Dutch scientist G. de Vries (1901) put forward a theory of variability based on the idea of ​​abrupt changes in hereditary properties as a result of mutations.

Works by T.G. Morgan and his school in the USA (A. Sturtevant, G. Meller, K. Bridges), carried out in 1910-1925, created the chromosomal theory of heredity, according to which genes are discrete elements of thread-like structures of the cell nucleus - chromosomes. The first genetic maps of the chromosomes of the fruit fly were compiled, which by that time had become the main object of genetics. The chromosomal theory of heredity was firmly based not only on genetic data, but also on observations about the behavior of chromosomes in mitosis and meiosis, and about the role of the nucleus in heredity. The successes of genetics are largely determined by the fact that it relies on its own method - hybridological analysis, the foundations of which were laid by Mendel.

Mendelian theory of heredity, i.e. the set of ideas about hereditary determinants and the nature of their transmission from parents to descendants, in its meaning, is directly opposite to Domendelian theories, in particular the theory of pangenesis proposed by Darwin. According to this theory, the characteristics of parents are direct, i.e. from all parts of the body are transmitted to offspring. Therefore, the nature of the descendant's trait must directly depend on the properties of the parent. This completely contradicts the conclusions made by Mendel: the determinants of heredity, i.e. genes are present in the body relatively independently of the body itself. The nature of traits (phenotype) is determined by their random combination. They are not modified by any part of the body and are in a dominant-recessive relationship. Thus, the Mendelian theory of heredity opposes the idea of ​​inheritance of traits acquired during individual development.

Mendel's experiments served as the basis for the development modern genetics- a science that studies two basic properties of the body - heredity and variability. He managed to identify patterns of inheritance thanks to fundamentally new methodological approaches:

1) Mendel chose the subject of his study well;

2) he analyzed the inheritance of individual traits in the offspring of crossed plants that differed in one, two, and three pairs of contrasting alternative traits. In each generation, records were kept separately for each pair of these characteristics;

3) he not only recorded the results obtained, but also carried out their mathematical processing.

The listed simple research techniques constituted a fundamentally new, hybridological method of studying inheritance, which became the basis for further research in genetics.

(1822-1884) Austrian naturalist, founder of the doctrine of heredity

Gregor Johann Mendel was born on July 22, 1822 in the village of Hinchitsy in the territory of modern Czech Republic in a peasant family. His father instilled in him a love of gardening, and Johann retained this love throughout his life.

The future scientist grew up as a smart and inquisitive boy. Teacher primary school, noticing the extraordinary abilities of his student, often told his father that Johann should continue his studies.

However, Mendel's family lived poorly, and therefore it was not easy to refuse Johann's help. In addition, the boy, helping his father run the household, early learned to care for fruit trees and plants, and in addition, he had a great understanding of flowers. And yet the father wanted to give his son an education. And eleven-year-old Johann, leaving home, continued his studies, first at school in Lipnik, and then at the gymnasium in Opava. But misfortune seemed to follow the Mendel family. Four years passed, and Johann's parents could no longer pay the costs of their son's education. He was forced to earn his own living by giving private lessons. However, Johann Mendel did not give up his studies. His graduation certificate, received in 1840 at the end of the gymnasium, showed “excellent” in almost all subjects. Mendel goes to study at the University of Olomouc, from which he was unable to graduate, since the family did not have enough money not only to pay for his son’s education, but also to live. And Mendel agrees with the proposal of the mathematics teacher to become a monk at a monastery in the city of Brno.

In 1843, Mendel became a monk and received a new name in the Augustinian monastery of Brno - Gregor. Having become a monk, Mendel was finally freed from the need and constant worry about a piece of bread. In addition, at young man there was an opportunity to study natural sciences. In 1851, with the permission of the abbot of the monastery, Mendel moved to Vienna and began studying at the university natural Sciences, most devoting time to physics and mathematics. But he still failed to obtain a diploma. Even upon entering the monastery, he received a small plot of land on which he was engaged in botany, selection and conducted his famous experiments on the hybridization of pea varieties. Mendel developed several varieties of vegetables and flowers, such as fuchsia, which was widely known among gardeners of that time.

He conducted experiments on crossing pea varieties in the period 1856-1863. They began before the appearance of Charles Darwin’s book “The Origin of Species” and ended 4 years after its publication. Mendel carefully studied this work.

Deliberately, with full understanding of the task at hand, he chose peas as the object of his experiments. This plant, being a self-pollinator, firstly, is represented by a number of pure-line varieties; secondly, the flowers are protected from the penetration of foreign pollen, which makes it possible to strictly control the reproduction processes; thirdly, the hybrids resulting from crossing pea varieties are quite fertile, and this made it possible to trace the progress of inheritance of traits over a number of generations. Achieving maximum clarity of experiments, Mendel chose seven pairs of clearly distinguishable characteristics for analysis. These differences were: smooth round or wrinkled and irregular shape seeds, red or white flower color, high or low plant, the shape of the pods is convex or laced but with grains, etc.

With perseverance and conscientiousness, which many researchers can envy, for eight years Mendel sowed peas, cared for them, transferred pollen from flower to flower and, most importantly, constantly counted how many red and white flowers, round and oblong, yellow flowers were produced and green peas.

The study of hybrids revealed a very definite pattern. It turned out that in hybrids, out of a pair of contrasting characters, only one appears, regardless of whether this trait comes from the mother or from the father. Mendel designates them as dominant. In addition, he discovered intermediate manifestations of properties. For example, crossing red-flowered peas with white-flowered peas produced hybrids with pink flowers. However, the intermediate manifestation does not change anything in the laws of splitting. Studying the offspring of hybrids, Mendel found that, along with dominant traits, some plants showed traits of another original parent, which do not disappear in hybrids, but go into a latent state. He called such traits recessive. The idea of ​​the recessiveness of hereditary properties and the term “recessiveness” itself, as well as the term “dominance”, have forever entered genetics.

Having examined each trait separately, the scientist was able to accurately calculate which part of the descendants would receive, for example, smooth seeds and which - wrinkled ones, and established a numerical ratio for each trait. He gave a classic example of the role of mathematics in biology. The numerical ratio obtained by the scientist turned out to be quite unexpected. For every plant with white flowers, there were three plants with red flowers. At the same time, the red or white color of flowers, for example, did not in any way affect the color of the fruit, the height of the stem, etc. Each trait is inherited by the plant independently of the other.

The conclusions that Mendel came to were far ahead of his time. He did not know that heredity is concentrated in the nuclei of cells, or rather, in the chromosomes of cells. At that time, the term “chromosome” did not yet exist. He didn't know what a gene was. However, the gaps in knowledge about heredity did not prevent the scientist from giving them a brilliant explanation. On February 8, 1865, at a meeting of the Society of Naturalists in Brno, the scientist made a report on plant hybridization. The report was met with bewildered silence. The listeners did not ask a single question; it seemed that they did not understand anything in this wise mathematics.

In accordance with the then existing procedures, Mendel's report was sent to Vienna, Rome, St. Petersburg, Krakow and other cities. Nobody paid any attention to him. The mixture of mathematics and botany contradicted all the prevailing concepts at that time. Of course, Mendel understood that his discovery ran counter to the views of other scientists on heredity that were dominant at that time. But there was another reason that pushed his discovery into the background. The fact is that during these years evolutionary theory C. Darwin made her victorious march around the world. And the scientists had no time for the whims of the pea offspring and the pedantic algebra of the Austrian naturalist.

Mendel soon abandoned his research on peas. The famous biologist Nägeli advised him to experiment with the hawkweed plant. These experiments produced strange and unexpected results. Mendel struggled in vain over the tiny yellowish and reddish flowers. He was unable to confirm the results obtained on peas. The cunning of the hawkweed was that the development of its seeds occurred without fertilization, and neither G. Mendel nor Nägeli knew this.

Even during the busy period of his passion for experiments with peas and hawkweed, he did not forget about his monastic and secular affairs. In this field, his persistence and perseverance were rewarded. In 1868, Mendel was elected to the high post of abbot of the monastery, which he held until the end of his life. And although the outstanding scientist lived a difficult life, he gratefully acknowledged that there were much more joyful and bright moments in it. According to him, scientific work The work he was doing brought him great satisfaction. He was convinced that in the near future it would be recognized throughout the world. And so it happened, however, after his death.

Gregor Johann Mendel died on January 6, 1884. In the obituary, among the many titles and merits of the scientist, there was no mention of the fact that he was the discoverer of the law of heredity.

Mendel was not mistaken in his prophecy made before his death. 16 years later, on the threshold of the 20th century, all biological science was excited by the message about a second time open laws Mendel. In 1900, G. de Vries in Holland, E. Cermak in Australia and Karl Correns in Germany independently rediscovered Mendel's laws and recognized his priority.

The rediscovery of these laws caused the rapid development of the science of heredity and variability of organisms - genetics.

What contribution to biology, the Austrian naturalist, botanist and religious figure, monk, founder of the doctrine of heredity, you will learn from this article.

Gregor Mendel's discoveries

The twentieth century was marked sensational discovery in the field of biology. Three botanist scientists Cermak, de Vries and Correns stated that 35 years ago a certain Czech monk and scientist Gregor Mendel, who was unknown to anyone, discovered the laws of inheritance of individual characters.

It is worth noting that Mendel was born into a poor peasant family of a gardener. His parents did not have the means to give their son a decent education. Therefore, the young man only graduated from high school and dreamed of university.

One day he went to the abbey and took monastic orders. He pursued one goal - knowledge. The monastery had a rich library, and he had the opportunity to study at the university. In addition, Gregor was interested in biology, and there was a garden bed near his cell. And he decided to carry out experiments in plant crossing. Peas acted as experimental subjects. For his experiments, the monk chose 7 pairs of varieties of this cultivated plant. Each pair of peas had its own difference. For example, the seeds of the first pair had a smooth structure, while the second pair had a wrinkled structure; in one the stem was no more than 60 cm, and in the second it reached 2 m; The color of the flower in one variety was white, while in the other pair it was purple.

For the first three years, Mendel sowed selected varieties to ensure that they were free of impurities. Then experiments on crossing began. During the experiments, he discovered that one of the plants is dominant and its characteristics suppressed the characteristics of the second plant. Mendel called this process “recessive.” So it was opened first law of heredity in biology. The following summer, he crossed the resulting red-flowering hybrids with the primary variety of red-flowering peas. And imagine his surprise when the plant bloomed and the flowers turned out to be white. This phenomenon, the manifestation of white color after one generation, Mendel called “splitting of characters.” So it was The second law of heredity in biology was discovered. Unfortunately, his discovery was not a success. Only 140 years later did humanity appreciate his experiments in biology.

Gregor Mendel(Gregor Johann Mendel) (1822-84) - Austrian naturalist, botanist and religious leader, monk, founder of the doctrine of heredity (Mendelism). By applying statistical methods to analyze the results of hybridization of pea varieties (1856-63), he formulated the laws of heredity.

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Gregor Johann Mendel Biology teacher Kuzyaeva A.M. Nizhny Novgorod

Gregor Johann Mendel (July 20, 1822 - January 6, 1884) Austrian naturalist, botanist and religious figure, Augustinian monk, abbot, founder of the doctrine of heredity (Mendelism). Using statistical methods to analyze the results of hybridization of pea varieties, he formulated the laws of heredity - Mendel's laws - which became the basis of modern genetics.

Johann Mendel was born on July 20, 1822, into the peasant family of Anton and Rosina Mendel in the small rural town of Heinzendorf (Austrian Empire, now the village of Hinchitsy, Czech Republic). The date July 22, which is often given in literature as the date of his birth, is in fact the date of his baptism. House of Mendel

He began to show interest in nature early, already working as a gardener as a boy. After graduating from high school, he studied for two years at the philosophical classes of the Olmutz Institute, in 1843 he became a monk at the Augustinian Monastery of St. Thomas in Brunn (now Brno, Czech Republic) and took the name Gregor. From 1844 to 1848 he studied at the Brunn Theological Institute. In 1847 he became a priest. Starobrnensky Monastery

He independently studied many sciences, replaced absent teachers of Greek and mathematics in one of the schools, but did not pass the exam for the title of teacher. In 1849-1851 he taught mathematics, Latin and Greek languages. In the period 1851-1853, thanks to the abbot, he studied natural history at the University of Vienna, including under the guidance of Unger, one of the first cytologists in the world. Franz Unger (1800-1870) University of Vienna

Since 1856, Gregor Mendel began to conduct well-thought-out extensive experiments in the monastery garden (7 * 35 meters) on crossing plants (primarily among carefully selected pea varieties) and elucidating the patterns of inheritance of traits in the offspring of hybrids. A separate card was created for each plant (10,000 pcs.).

In 1863 he completed the experiments, and on February 8, 1865, at two meetings of the Brunn Society of Naturalists, he reported the results of his work. In 1866, his article “Experiments on plant hybrids” was published in the proceedings of the society, which laid the foundations of genetics as an independent science.

Mendel ordered 40 separate prints of his work, almost all of which he sent to major botanical researchers, but received only one favorable response - from Karl Nägeli, professor of botany from Munich. He proposed repeating similar experiments on the hawkweed, which he himself was studying at that time. Later they will say that Nägeli’s advice delayed the development of genetics for 4 years... Karl Nägeli (1817-1891)

Kingdom: Plants Division: Angiosperms Class: Dicotyledonous Order: Astroflora Family: Asteraceae Genus: Hawkweed Mendel tried to repeat the experiments on the hawkweed, then bees. In both cases, the results he obtained on peas were not confirmed. The reason was that the mechanisms of fertilization of both hawkweeds and bees had features that were not yet known to science at that time (reproduction using parthenogenesis), and the crossing methods that Mendel used in his experiments did not take these features into account. In the end, the great scientist himself lost faith in his discovery.

In 1868, Mendel was elected abbot of the Starobrno Monastery and more biological research didn't study. Mendel died in 1884. Beginning in 1900, after the almost simultaneous publication of articles by three botanists - H. De Vries, K. Correns and E. Cermak-Zesenegg, who independently confirmed Mendel's data with their own experiments, there was an instant explosion of recognition of his work. 1900 is considered the year of birth of genetics. H. De Vries H. De Vries E. Cermak

The significance of the works of Gregor Mendel Mendel created the scientific principles for the description and study of hybrids and their offspring (which forms to crossbreed, how to conduct analysis in the first and second generations). Developed and applied an algebraic system of symbols and notation of features, which represented an important conceptual innovation. Formulated two basic principles, or laws of inheritance of characteristics over a series of generations, allowing predictions to be made. Mendel implicitly expressed the idea of ​​discreteness and binarity of hereditary inclinations: each trait is controlled by a maternal and paternal pair of inclinations (or genes, as they later came to be called), which are transmitted to hybrids through parental reproductive cells and do not disappear anywhere. The makings of characters do not influence each other, but diverge during the formation of germ cells and are then freely combined in descendants (laws of splitting and combining characters).

Illustration of Mendel's laws

On January 6, 1884, Gregor Johann Mendel died. Shortly before his death, Mendel said: “If I had to go through bitter hours, then I must admit with gratitude that there were many more beautiful, good hours. My scientific works gave me a lot of satisfaction, and I am convinced that it won’t be long before the whole world recognizes the results of these works.” The monument to Mendel in front of the memorial museum in Brno was built in 1910 with funds raised by scientists from all over the world.

MENDEL, GREGOR JOHANN(Mendel, Gregor Johann) (1822–1884), Austrian biologist, founder of genetics.

Born July 22, 1822 in Heinzendorf (Austria-Hungary, now Gincice, Czech Republic). He studied at the schools of Heinzendorf and Lipnik, then at the district gymnasium in Troppau. In 1843 he graduated from philosophical classes at the university in Olmutz and became a monk at the Augustinian Monastery of St. Thomas in Brunn (Austria, now Brno, Czech Republic). He served as an assistant pastor and taught natural history and physics at school. In 1851–1853 he was a volunteer student at the University of Vienna, where he studied physics, chemistry, mathematics, zoology, botany and paleontology. Upon returning to Brunn he worked as an assistant teacher in a secondary school until 1868, when he became abbot of the monastery. In 1856, Mendel began his experiments on crossing different varieties of peas that differed in single, strictly defined characteristics (for example, the shape and color of seeds). Accurate quantitative accounting of all types of hybrids and statistical processing of the results of experiments that he conducted for 10 years allowed him to formulate the basic laws of heredity - the splitting and combination of hereditary “factors”. Mendel showed that these factors are separate and do not merge or disappear when crossed. Although when crossing two organisms with contrasting traits (for example, yellow or green seeds), only one of them appears in the next generation of hybrids (Mendel called it “dominant”), the “disappeared” (“recessive”) trait reappears in subsequent generations. (Today Mendel's hereditary "factors" are called genes.)

Mendel reported the results of his experiments to the Brunn Society of Naturalists in the spring of 1865; a year later his article was published in the proceedings of this society. Not a single question was asked at the meeting, and the article received no responses. Mendel sent a copy of the article to K. Nägeli, a famous botanist and authoritative expert on problems of heredity, but Nägeli also failed to appreciate its significance. And only in 1900, Mendel’s forgotten work attracted everyone’s attention: three scientists at once, H. de Vries (Holland), K. Correns (Germany) and E. Chermak (Austria), having conducted their own experiments almost simultaneously, became convinced of the validity of Mendel’s conclusions . The law of independent segregation of characters, now known as Mendel's law, laid the foundation for a new direction in biology - Mendelism, which became the foundation of genetics.

Mendel himself, after unsuccessful attempts to obtain similar results by crossing other plants, stopped his experiments and until the end of his life was engaged in beekeeping, gardening and meteorological observations.

Among the scientist’s works - Autobiography(Gregorii Mendel autobiographia iuvenilis, 1850) and a number of articles, including Experiments on plant hybridization (Versuche über Pflanzenhybriden, in "Proceedings of the Brunn Society of Natural Scientists", vol. 4, 1866).