Who is Mendel? Biography of Mendel

Gregor Johann Mendel became the founder of the doctrine of heredity, the creator of a new science - genetics. But he was so ahead of his time that during Mendel's life, although his works were published, no one understood the significance of his discoveries. Only 16 years after his death, scientists re-read and comprehended what Mendel wrote.

Johann Mendel was born on July 22, 1822 into a peasant family in the small village of Hinchitsy on the territory of the modern Czech Republic, and then the Austrian Empire.

The boy was distinguished by his extraordinary abilities, and at school he was given only excellent grades, as “the first of those who distinguished himself in the class.” Johann's parents dreamed of bringing their son “into the people” and giving him a good education. This was hindered by extreme need, from which Mendel’s family could not escape.

And yet, Johann managed to finish first the gymnasium, and then two-year philosophical courses. He writes in his short autobiography that he “felt that he could no longer withstand such tension, and saw that after completing his course of philosophical studies he would have to find a position for himself that would free him from the painful worries of his daily bread...”

In 1843, Mendel entered the Augustinian monastery as a novice in Brünn (now Brno). This was not at all easy to do;

withstand severe competition (three people for one place).

And so the abbot - the abbot of the monastery - uttered a solemn phrase, addressing Mendel prostrate on the floor: “Throw off the old man who was created in sin! Become a new person! He tore off Johann's worldly clothes - an old frock coat - and put a cassock on him. According to custom, upon taking monastic orders, Johann Mendel received his middle name - Gregor.

Having become a monk, Mendel was finally freed from eternal need and concern for a piece of bread. He had a desire to continue his education, and in 1851 the abbot sent him to study natural sciences at the University of Vienna. But failure awaited him here. Mendel, who will be included in all biology textbooks as the creator of an entire science - genetics, failed the biology exam. Mendel was excellent at botany, but his knowledge of zoology was clearly weak. When asked to talk about the classification of mammals and their economic importance, he described such unusual groups as “beasts with paws” and “clawed animals.” Of the “clawed animals,” where Mendel included only the dog, wolf and cat, “only the cat is of economic importance,” because it “feeds on mice” and “its soft, beautiful skin is processed by furriers.”

Having failed the exam, upset Meidel abandoned his dreams of obtaining a diploma. However, even without it, Mendel, as an assistant teacher, taught physics and biology at a real school in Brünn.

At the monastery, he began to seriously engage in gardening and asked the abbot for a small fenced plot of land - 35x7 meters - for his garden. Who would have imagined that universal biological laws of heredity would be established in this tiny area? In the spring of 1854, Mendel planted peas here.

And even earlier, a hedgehog, a fox and many mice - gray and white - will appear in his monastic cell. Mendel crossed mice and observed what kind of offspring they got. Perhaps, if fate had turned out differently, opponents would later have called Mendel’s laws not “pea laws”, but “mouse laws”? But the monastery authorities found out about Brother Gregor’s experiments with mice and ordered that the mice be removed so as not to cast a shadow on the reputation of the monastery.

Then Mendel transferred his experiments to peas growing in the monastery garden. Later he jokingly told his guests:

Would you like to see my children?

Surprised guests walked with him into the garden, where he pointed out to them the beds of peas.

Scientific conscientiousness forced Mendel to extend his experiments over eight long years. What were they? Mendel wanted to find out how various traits are inherited from generation to generation. In peas, he identified several (seven in total) clear characteristics: smooth or wrinkled seeds, red or white flower color, green or yellow color of seeds and beans, tall or short plant, etc.

The peas bloomed eight times in his garden. For each pea bush, Mendel filled out a separate card (10,000 cards!), which contained detailed characteristics of the plant on these seven points. How many thousands of times did Mendel transfer the pollen of one flower to the stigma of another with tweezers! For two years, Mendel painstakingly checked the purity of the pea lines. From generation to generation, only the same signs should have appeared in them. Then he began to cross plants with different characteristics to obtain hybrids (crosses).

What did he find out?

If one of the parent plants had green peas, and the second had yellow ones, then all the peas of their descendants in the first generation will be yellow.

A pair of plants with a high stem and a low stem will produce first generation offspring with only a tall stem.

A pair of plants with red and white flowers will produce first generation offspring with only red flowers. And so on.

Perhaps the whole point is from whom exactly - “father” or “mother” - the descendants received their

signs? Nothing like this. Surprisingly, it didn't matter in the slightest.

So, Mendel precisely established that the characteristics of the “parents” do not “merge” together (red and white flowers do not turn pink in the descendants of these plants). This was an important scientific discovery. Charles Darwin, for example, thought differently.

Mendel called the dominant trait in the first generation (for example, red flowers) dominant, and the “receding” trait (white flowers) - recessive.

What will happen in the next generation? It turns out that the “grandchildren” will again “resurface” the suppressed, recessive traits of their “grandparents.” At first glance, there will be unimaginable confusion. For example, the color of the seeds will be “grandfather”, the color of the flowers will be “grandmother”, and the height of the stem will be “grandfather” again. And each plant is different. How to figure all this out? And is this even conceivable?

Mendel himself admitted that resolving this issue “required a certain amount of courage.”

Gregor Johann Mendel.

Mendel's brilliant discovery was that he did not study whimsical combinations of traits, but examined each trait separately.

He decided to accurately calculate which part of the descendants would receive, for example, red flowers, and which – white, and establish a numerical ratio for each trait. This was a completely new approach to botany. So new that it was ahead of the development of science by as much as three and a half decades. And he remained incomprehensible all this time.

The numerical relationship established by Mendel was quite unexpected. For every plant with white flowers, there were on average three plants with red flowers. Almost exactly - three to one!

At the same time, the red or white color of flowers, for example, does not in any way affect the yellow or green color of peas. Each trait is inherited independently of the other.

But Mendel not only established these facts. He gave them a brilliant explanation. From each of the parents, the germ cell inherits one “hereditary inclination” (later they will be called genes). Each of the inclinations determines some characteristic - for example, the red color of flowers. If the inclinations that determine red and white coloration enter a cell at the same time, then only one of them appears. The second one remains hidden. In order for the white color to appear again, a “meeting” of two inclinations of white color is necessary. According to probability theory, this will happen in the next generation

Abbot's coat of arms of Gregor Mendel.

On one of the fields of the shield on the coat of arms there is a pea flower.

once for every four combinations. Hence the 3 to 1 ratio.

And finally, Mendel concluded that the laws he discovered apply to all living things, for “the unity of the plan for the development of organic life is beyond doubt.”

In 1863, Darwin's famous book On the Origin of Species was published in German. Mendel carefully studied this work with a pencil in his hands. And he expressed the result of his thoughts to his colleague at the Brunn Society of Naturalists, Gustav Nissl:

That's not all, there's still something missing!

Nissl was dumbfounded by such an assessment of Darwin’s “heretical” work, incredible from the mouth of a pious monk.

Mendel then modestly kept silent about the fact that, in his opinion, he had already discovered this “missing thing.” Now we know that this was so, that the laws discovered by Mendel made it possible to illuminate many dark places in the theory of evolution (see article “Evolution”). Mendel perfectly understood the significance of his discoveries. He was confident in the triumph of his theory and prepared it with amazing restraint. He remained silent about his experiments for eight whole years, until he was convinced of the reliability of the results obtained.

And finally, the decisive day came - February 8, 1865. On this day, Mendel made a report on his discoveries at the Brunn Society of Naturalists. Mendel's colleagues listened in amazement to his report, peppered with calculations that invariably confirmed the ratio of “3 to 1.”

What does all this math have to do with botany? The speaker clearly does not have a botanical mind.

And then, this persistently repeated “three to one” ratio. What are these strange “magic numbers”? Is this Augustinian monk, hiding behind botanical terminology, trying to smuggle something like the dogma of the Holy Trinity into science?

Mendel's report was met with bewildered silence. He was not asked a single question. Mendel was probably prepared for any reaction to his eight-year work: surprise, disbelief. He was going to invite his colleagues to double-check their experiments. But he could not have foreseen such a dull misunderstanding! Really, there was something to despair about.

A year later, the next volume of the “Proceedings of the Society of Naturalists in Brünn” was published, where Mendel’s report was published in an abbreviated form under the modest title “Experiments on plant hybrids.”

Mendel's work was included in 120 scientific libraries in Europe and America. But in only three of them over the next 35 years did someone’s hand open the dusty volumes. Mendel's work was briefly mentioned three times in various scientific works.

In addition, Mendel himself sent 40 reprints of his work to some prominent botanists. Only one of them, the famous biologist from Munich Karl Nägeli, sent a response letter to Mendel. Nägeli began his letter with the phrase that “the experiments with peas are not completed” and “they should be started over.” To begin again the colossal work on which Mendel spent eight years of his life!

Nägeli advised Mendel to experiment with the hawkweed. Hawkweed was Naegeli’s favorite plant; he even wrote a special work about it - “Hawstripes of Central Europe.” Now, if we manage to confirm the results obtained on peas using hawkweed, then...

Mendel took up the hawkweed, a plant with tiny flowers, which was so difficult for him to work with due to his myopia! And what’s most unpleasant is that the laws established in experiments with peas (and confirmed on fuchsia and corn, bluebells and snapdragons) were not confirmed on the hawkweed. Today we can add: and could not be confirmed. After all, the development of seeds in the hawkweed occurs without fertilization, which neither Naegeli nor Mendel knew.

Biologists later said that Naegeli's advice delayed the development of genetics for 40 years.

In 1868, Mendel abandoned his experiments in breeding hybrids. It was then that he was elected to

the high position of abbot of the monastery, which he held until the end of his life. Shortly before his death (October 1

1883), as if summing up his life, he said:

“If I had to go through bitter hours, I had many more wonderful, good hours. My scientific works have given 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.”

Half the city gathered for his funeral. Speeches were made in which the merits of the deceased were listed. But, surprisingly, not a word was said about the biologist Mendel whom we know.

All the papers remaining after Mendel's death - letters, unpublished articles, observation journals - were thrown into the oven.

But Mendel was not mistaken in his prophecy, made 3 months before his death. And 16 years later, when the name of Mendel was recognized by the entire civilized world, descendants rushed to look for individual pages of his notes that accidentally survived the flames. From these scraps they recreated the life of Gregor Johann Mendel and the amazing fate of his discovery, which we described.

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Mendel Gregor Johann

The Austrian priest and botanist Gregor Johann Mendel laid the foundations of the science of genetics. He mathematically deduced the laws of genetics, which are now called after him.

Gregor Johann Mendel

Johann Mendel was born on July 22, 1822 in Heisendorf, Austria. As a child, he began to show interest in studying plants and the environment. After two years of study at the Institute of Philosophy in Olmütz, Mendel decided to enter a monastery in Brünn. This happened in 1843. During the rite of tonsure as a monk, he was given the name Gregor. Already in 1847 he became a priest.

The life of a clergyman consists of more than just prayers. Mendel managed to devote a lot of time to study and science. In 1850, he decided to take the exams to become a teacher, but failed, receiving a “D” in biology and geology. Mendel spent 1851-1853 at the University of Vienna, where he studied physics, chemistry, zoology, botany and mathematics. Upon returning to Brunn, Father Gregor began teaching at school, although he never passed the exam to become a teacher. In 1868, Johann Mendel became abbot.

Mendel conducted his experiments, which ultimately led to the sensational discovery of the laws of genetics, in his small parish garden since 1856. It should be noted that the environment of the holy father contributed to scientific research. The fact is that some of his friends had a very good education in the field of natural science. They often attended various scientific seminars, in which Mendel also participated. In addition, the monastery had a very rich library, of which Mendel, naturally, was a regular. He was very inspired by Darwin's book "The Origin of Species", but it is known for certain that Mendel's experiments began long before the publication of this work.

On February 8 and March 8, 1865, Gregor (Johann) Mendel spoke at meetings of the Natural History Society in Brünn, where he spoke about his unusual discoveries in an as yet unknown field (which would later become known as genetics). Gregor Mendel conducted experiments on simple peas, however, later the range of experimental objects was significantly expanded. As a result, Mendel came to the conclusion that the various properties of a particular plant or animal do not just appear out of thin air, but depend on the “parents”. Information about these hereditary traits is passed on through genes (a term coined by Mendel, from which the term "genetics" is derived). Already in 1866, Mendel's book "Versuche uber Pflanzenhybriden" ("Experiments with plant hybrids") was published. However, contemporaries did not appreciate the revolutionary nature of the discoveries of the modest priest from Brunn.

Mendel's scientific research did not distract him from his daily duties. In 1868 he became abbot, mentor of the entire monastery. In this position, he excellently defended the interests of the church in general and the Brunn monastery in particular. He was good at avoiding conflicts with the authorities and avoiding excessive taxation. He was very loved by parishioners and students, young monks.

On January 6, 1884, Gregor's father (Johann Mendel) passed away. He is buried in his native Brunn. Fame as a scientist came to Mendel after his death, when experiments similar to his experiments in 1900 were independently carried out by three European botanists, who came to results similar to Mendel's.

Gregor Mendel - teacher or monk?

Mendel's fate after the Theological Institute is already arranged. The twenty-seven-year-old canon, ordained a priest, received an excellent parish in Old Brünn. He has been preparing to take exams for a doctorate in theology for a whole year when serious changes occur in his life. Georg Mendel decides to change his fate quite dramatically and refuses to perform religious services. He would like to study nature and for the sake of this passion, he decides to take a place at the Znaim Gymnasium, where by this time the 7th grade was opening. He asks for a position as a “sub-professor.”

In Russia, “professor” is a purely university title, but in Austria and Germany even the teacher of first-graders was called this title. Gymnasium suplent - this can rather be translated as “ordinary teacher”, “teacher’s assistant”. This could be a person with excellent knowledge of the subject, but since he did not have a diploma, he was hired rather temporarily.

A document has also been preserved explaining such an unusual decision of Pastor Mendel. This is an official letter to Bishop Count Schafgotsch from the abbot of the monastery of St. Thomas, Prelate Nappa.” Your Gracious Episcopal Eminence! The High Imperial-Royal Land Presidium, by decree No. Z 35338 of September 28, 1849, considered it best to appoint Canon Gregor Mendel as supplanter at the Znaim Gymnasium. “... This canon has a God-fearing lifestyle, abstinence and virtuous behavior, completely corresponding to his rank, combined with great devotion to the sciences... He is, however, somewhat less suitable for the care of the souls of the laity, for once he finds himself at the bedside of the sick , as at the sight of his suffering, we are overcome by insurmountable confusion and from this he himself becomes dangerously ill, which prompts me to resign from him the duties of a confessor.”

So, in the fall of 1849, canon and supporter Mendel arrived in Znaim to begin new duties. Mendel earns 40 percent less than his colleagues who had degrees. He is respected by his colleagues and loved by his students. However, he does not teach natural science subjects at the gymnasium, but classical literature, ancient languages and mathematics. Need a diploma. This will make it possible to teach botany and physics, mineralogy and natural history. There were 2 paths to the diploma. One is to graduate from university, the other way - a shorter one - is to pass exams in Vienna before a special commission of the Imperial Ministry of Cults and Education for the right to teach such and such subjects in such and such classes.

Mendel's laws

The cytological foundations of Mendel's laws are based on:

* pairing of chromosomes (pairing of genes that determine the possibility of developing any trait)

* features of meiosis (processes occurring in meiosis, which ensure the independent divergence of chromosomes with the genes located on them to different pluses of the cell, and then into different gametes)

* features of the fertilization process (random combination of chromosomes carrying one gene from each allelic pair)

Mendel's scientific method

The basic patterns of transmission of hereditary characteristics from parents to descendants were established by G. Mendel in the second half of the 19th century. He crossed pea plants that differed in individual traits, and based on the results obtained, he substantiated the idea of the existence of hereditary inclinations responsible for the manifestation of traits. In his works, Mendel used the method of hybridological analysis, which has become universal in the study of patterns of inheritance of traits in plants, animals and humans.

Unlike his predecessors, who tried to trace the inheritance of many characteristics of an organism in the aggregate, Mendel studied this complex phenomenon analytically. He observed the inheritance of just one pair or a small number of alternative (mutually exclusive) pairs of characters in garden pea varieties, namely: white and red flowers; short and tall stature; yellow and green, smooth and wrinkled pea seeds, etc. Such contrasting characteristics are called alleles, and the terms “allele” and “gene” are used as synonyms.

For crossings, Mendel used pure lines, that is, the offspring of one self-pollinating plant in which a similar set of genes is preserved. Each of these lines did not produce splitting of characters. It was also significant in the methodology of hybridological analysis that Mendel was the first to accurately calculate the number of descendants - hybrids with different characteristics, i.e., mathematically processed the results obtained and introduced the symbolism accepted in mathematics to record various crossing options: A, B, C, D etc. With these letters he denoted the corresponding hereditary factors.

In modern genetics, the following conventions for crossing are accepted: parental forms - P; first generation hybrids obtained from crossing - F1; hybrids of the second generation - F2, third - F3, etc. The very crossing of two individuals is indicated by the sign x (for example: AA x aa).

Of the many different characters of crossed pea plants, in his first experiment Mendel took into account the inheritance of only one pair: yellow and green seeds, red and white flowers, etc. Such crossing is called monohybrid. If the inheritance of two pairs of characters is traced, for example, yellow smooth pea seeds of one variety and green wrinkled ones of another, then the crossing is called dihybrid. If three or more pairs of characteristics are taken into account, the crossing is called polyhybrid.

Patterns of inheritance of traits

Alleles are designated by letters of the Latin alphabet, while Mendel called some traits dominant (predominant) and designated them in capital letters - A, B, C, etc., others - recessive (inferior, suppressed), which he designated in lowercase letters - a , in, with, etc. Since each chromosome (the carrier of alleles or genes) contains only one of two alleles, and homologous chromosomes are always paired (one paternal, the other maternal), in diploid cells there is always a pair of alleles: AA, aa, Aa, BB, bb. Bb, etc. Individuals and their cells that have a pair of identical alleles (AA or aa) in their homologous chromosomes are called homozygous. They can form only one type of germ cells: either gametes with the A allele or gametes with the a allele. Individuals who have both dominant and recessive Aa genes in the homologous chromosomes of their cells are called heterozygous; When germ cells mature, they form two types of gametes: gametes with the A allele and gametes with the a allele. In heterozygous organisms, the dominant allele A, which manifests itself phenotypically, is located on one chromosome, and the recessive allele a, suppressed by the dominant, is in the corresponding region (locus) of another homologous chromosome. In the case of homozygosity, each of the pair of alleles reflects either the dominant (AA) or recessive (aa) state of the genes, which will manifest their effect in both cases. The concept of dominant and recessive hereditary factors, first used by Mendel, is firmly established in modern genetics. Later the concepts of genotype and phenotype were introduced. Genotype is the totality of all genes that a given organism has. Phenotype is the totality of all the signs and properties of an organism that are revealed in the process of individual development under given conditions. The concept of phenotype extends to any characteristics of an organism: features of the external structure, physiological processes, behavior, etc. The phenotypic manifestation of characteristics is always realized on the basis of the interaction of the genotype with a complex of internal and external environmental factors.

Mendel's three laws

mendel scientific inheritance crossing

G. Mendel formulated, based on an analysis of the results of monohybrid crossing, and called them rules (later they became known as laws). As it turned out, when crossing plants of two pure lines of peas with yellow and green seeds in the first generation (F1), all hybrid seeds were yellow. Consequently, the trait of yellow seed color was dominant. In literal expression it is written like this: R AA x aa; all the gametes of one parent are A, A, the other - a, a, the possible combination of these gametes in zygotes is equal to four: Aa, Aa, Aa, Aa, i.e. in all F1 hybrids there is a complete predominance of one trait over another - all the seeds are yellow. Similar results were obtained by Mendel when analyzing the inheritance of the other six pairs of studied characters. Based on this, Mendel formulated the rule of dominance, or the first law: in a monohybrid crossing, all offspring in the first generation are characterized by uniformity in phenotype and genotype - the color of the seeds is yellow, the combination of alleles in all hybrids is Aa. This pattern is also confirmed in cases where there is no complete dominance: for example, when crossing a night beauty plant with red flowers (AA) with a plant with white flowers (aa), all hybrids fi (Aa) have flowers that are not red, and pink ones - their color has an intermediate color, but the uniformity is completely preserved. After Mendel’s work, the intermediate nature of inheritance in F1 hybrids was revealed not only in plants, but also in animals, therefore the law of dominance—Mendel’s first law—is also commonly called the law of uniformity of first-generation hybrids. From seeds obtained from F1 hybrids, Mendel grew plants, which he either crossed with each other or allowed them to self-pollinate. Among the descendants of F2, a split was revealed: in the second generation there were both yellow and green seeds. In total, Mendel obtained 6022 yellow and 2001 green seeds in his experiments, their numerical ratio is approximately 3:1. The same numerical ratios were obtained for the other six pairs of pea plant traits studied by Mendel. As a result, Mendel's second law is formulated as follows: when crossing hybrids of the first generation, their offspring give segregation in a ratio of 3:1 with complete dominance and in a ratio of 1:2:1 with intermediate inheritance (incomplete dominance). The diagram of this experiment in literal expression looks like this: P Aa x Aa, their gametes A and I, the possible combination of gametes is equal to four: AA, 2Aa, aa, i.e. e. 75% of all seeds in F2, having one or two dominant alleles, were yellow in color and 25% were green. The fact that recessive traits appear in them (both alleles are recessive-aa) indicates that these traits, as well as the genes that control them, do not disappear, do not mix with dominant traits in a hybrid organism, their activity is suppressed by the action of dominant genes. If both genes that are recessive for a given trait are present in the body, then their action is not suppressed, and they manifest themselves in the phenotype. The genotype of hybrids in F2 has a ratio of 1:2:1.

During subsequent crosses, the F2 offspring behave differently: 1) of 75% of plants with dominant traits (with genotypes AA and Aa), 50% are heterozygous (Aa) and therefore in F3 they will give a 3:1 split, 2) 25% of plants are homozygous according to the dominant trait (AA) and during self-pollination in Fz they do not produce splitting; 3) 25% of the seeds are homozygous for the recessive trait (aa), have a green color and, when self-pollinated in F3, do not split the characters.

To explain the essence of the phenomena of uniformity of hybrids of the first generation and the splitting of characters in hybrids of the second generation, Mendel put forward the hypothesis of gamete purity: every heterozygous hybrid (Aa, Bb, etc.) forms “pure” gametes carrying only one allele: either A or a , which was subsequently fully confirmed in cytological studies. As is known, during the maturation of germ cells in heterozygotes, homologous chromosomes will end up in different gametes and, therefore, the gametes will contain one gene from each pair.

Test crossing is used to determine the heterozygosity of a hybrid for a particular pair of traits. In this case, the first generation hybrid is crossed with a parent homozygous for the recessive gene (aa). Such crossing is necessary because in most cases homozygous individuals (AA) are not phenotypically different from heterozygous individuals (Aa) (pea seeds from AA and Aa are yellow). Meanwhile, in the practice of breeding new breeds of animals and plant varieties, heterozygous individuals are not suitable as initial ones, since when crossed their offspring will produce splitting. Only homozygous individuals are needed. The diagram of analyzing crossing in literal expression can be shown in two ways:

a heterozygous hybrid individual (Aa), phenotypically indistinguishable from a homozygous one, is crossed with a homozygous recessive individual (aa): P Aa x aa: their gametes are A, a and a,a, distribution in F1: Aa, Aa, aa, aa, t i.e. a 2:2 or 1:1 split is observed in the offspring, confirming the heterozygosity of the test individual;

2) the hybrid individual is homozygous for dominant traits (AA): P AA x aa; their gametes are A A and a, a; no cleavage occurs in F1 progeny

The purpose of dihybrid crossing is to trace the inheritance of two pairs of characters simultaneously. During this crossing, Mendel established another important pattern: the independent divergence of alleles and their free, or independent, combination, later called Mendel’s third law. The starting material was pea varieties with yellow smooth seeds (AABB) and green wrinkled ones (aavv); the first are dominant, the second are recessive. Hybrid plants from f1 maintained uniformity: they had yellow smooth seeds, were heterozygous, and their genotype was AaBb. Each of these plants produces four types of gametes during meiosis: AB, Av, aB, aa. To determine combinations of these types of gametes and take into account the results of splitting, the Punnett grid is now used. In this case, the genotypes of the gametes of one parent are placed horizontally above the lattice, and the genotypes of the gametes of the other parent are placed vertically at the left edge of the lattice (Fig. 20). Four combinations of one and the other type of gamete in F2 can give 16 variants of zygotes, the analysis of which confirms the random combination of the genotypes of each of the gametes of one and the other parent, giving a splitting of traits by phenotype in the ratio 9: 3: 3: 1.

It is important to emphasize that not only the characteristics of the parent forms were revealed, but also new combinations: yellow wrinkled (AAbb) and green smooth (aaBB). Yellow smooth pea seeds are phenotypically similar to the first generation descendants from a dihybrid cross, but their genotype can have different options: AABB, AaBB, AAVb, AaBB; new combinations of genotypes turned out to be phenotypically green smooth - aaBB, aaBB and phenotypically yellow wrinkled - AAbb, Aavv; Phenotypically, green wrinkled ones have a single genotype, aabb. In this crossing, the shape of the seeds is inherited regardless of their color. The 16 variants of combinations of alleles in zygotes considered illustrate combinative variability and independent splitting of pairs of alleles, i.e. (3:1)2.

Independent combination of genes and splitting based on it in F2 in the ratio. 9:3:3:1 was later confirmed for a large number of animals and plants, but under two conditions:

1) dominance must be complete (with incomplete dominance and other forms of gene interaction, the numerical ratios have a different expression); 2) independent splitting is applicable for genes localized on different chromosomes.

Mendel's third law can be formulated as follows: members of one pair of alleles are separated in meiosis independently of the members of other pairs, combining in gametes randomly, but in all possible combinations (with a monohybrid crossing there were 4 such combinations, with a dahybrid - 16, with a trihybrid crossing heterozygotes form 8 types of gametes, for which 64 combinations are possible, etc.).

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Childhood and youth

Little is known about the early years of the scientist’s biography. Born on July 20, 1822 in Heinzendorf, historical region of Silesia, territorially belonging to the Austrian Empire (now the village of Gincice, Czech Republic). Often sources indicate the baptism of the future monk instead of the birthday - July 22, which is erroneous.

The second child in the peasant family of Anton and Rosina, where daughters Veronica and Teresia were also born. He had German-Slavic roots. The land where the family lived belonged to the Mendel family for over a century. Today the scientist’s father’s house has been turned into a museum.

He showed a love for nature at an early age. He enthusiastically worked as a gardener; as a boy, he was engaged in beekeeping. He grew up as a weak child - during his studies he often missed months of classes due to illness. Having completed his education at a rural school, he entered the Troppau gymnasium (now the Czech city of Opava), where he studied for 6 classes.

Then for 3 years he studied practical and theoretical philosophy and physics at the Olmutz Institute (now the Czech Palacky University in Olomouc). An interesting fact is that at the same time, the Faculty of Natural History and Agriculture was headed by Johann Karl Nestler, who was interested in the study of hereditary characteristics of plants and animals, for example, sheep.

Mendel had a hard time with financial insolvency because he could not pay for his education. In order for her brother to study further, Theresia gave her own dowry. Later, Gregor repaid the debt in full, providing support to his three nephews - his sister's sons. Two of the youths under his protectorate later became doctors.

In 1843, Mendel decided to become a monk. To a greater extent, this decision was dictated not by the piety of the farmer’s son, but by the fact that clergy received education for free. According to him, monastic life eliminated the “eternal worry about livelihood.” After being tonsured at the Augustinian monastery of St. Thomas in Brunn (now Czech Brno), he received the name Gregor, Gregor Johann Mendel, and immediately began studying at the theological institute. At the age of 25 he was ordained as a priest.

The science

Mendel, a natural scientist and at the same time a religious figure, is an extraordinary figure. What adds to the piquancy of the situation is that the area he studied in the future gave rise to a new scientific discipline that decomposes the theory of divine design into genomes. Gregor's thirst for knowledge is all-consuming. He constantly read volumes of scientific literature and substituted for teachers in lessons at a local school. The man dreamed of passing the exam to become a teacher, but failed in geology and biology.

In 1849-1851 he taught languages and mathematics to students at the Znojmo Gymnasium. Later he moved to Vienna, where until 1853 he studied natural history at the University of Vienna under the patronage of the botanist and one of the first cytologists Franz Unger and physics with the famous Christian Doppler.

Upon returning to Brunne, he taught these disciplines at the Higher Real School, although he was not a certified specialist. In 1856 he again tried to pass the exams to become a teacher, but again failed in biology. In the same year, Mendel became seriously interested in scientific experiments with plants, showing interest in the hybridization of which back in Vienna. For 7 years, until 1863, Gregor experimented with peas in the monastery garden and during these years he made discoveries.

Work on plant hybridization was carried out long before Mendel, but only he managed to derive patterns and structure the main theses of the work, which geneticists would use until the 70s of the twentieth century.

More than 10 thousand experiments involved over 20 varieties of peas, differing in flowers and seeds. Titanic work, considering that each pea must be inspected manually. To transmit in crossed forms only one trait, “wrinkled-smooth,” Gregor looked at more than 7 thousand peas, and there were 7 such traits in the work.

The knowledge gained formed the basis of the doctrine of heredity, on which genetics is based. In 1865, he published a scientific report “Experiments on plant hybrids” in one of the volumes of the Society of Brunn Naturalists, where he formed the basic patterns of inheritance, which went down in history as Mendel’s laws.

The information summarized by the monk sounds like this:

First generation hybrids are identical and carry the dominant trait of one of the parents. For example, when crossing peas with white and red flowers, offspring with only red inflorescences are born.
Hybrids of the second generation are split, that is, divided into those who receive the dominant characteristics of the parent, and those who received the recessive ones not by chance, but in a mathematically expressed ratio.
Both traits are found in different combinations and exist separately, while a hybrid with a manifested dominant trait can be a carrier of recessive inclinations and, conversely, which will appear in subsequent generations.
Male and female gametes are combined by chance, and not in accordance with the inclinations they carry.

Gregor was convinced that research achievements were of fundamental importance for the development of science, so he ordered dozens of prints of the work and sent them to prominent botanists of the time. Alas, contemporaries were not interested in the publication. Only a professor at the University of Munich, Karl von Nägeli, advised testing the theory on other species.

Mendel carried out a series of experiments on crossing other plants and insects - bees, his favorite from childhood. Unfortunately, Gregor was disappointed. By coincidence, both the type of plant he chose and the bees had characteristics of the fertilization process and could reproduce by parthenogenesis - the “virgin way”. Because of this, the data obtained from experiments with peas were not confirmed.

His contribution to science was appreciated much later - at the beginning of the twentieth century, when in 1900 a number of scientists independently voiced the postulates that Mendel had derived in the previous century. This year is usually designated as the year of birth of the science of genetics. The role of Mendelism in it is great.

Soviet geneticist Boris Astaurov described Gregor's scientific quest as follows:

“The fate of Mendel’s classic work is perverse and not devoid of drama. Although he discovered, clearly demonstrated and largely understood very general patterns of heredity, the biology of that time had not yet matured to realize their fundamental nature.
Gregor Mendel himself, with amazing insight, foresaw the general significance of the patterns discovered in peas. A few more years passed, and he passed away, not foreseeing what passions would rage around his name and what glory it would ultimately be covered with.”

Religion

Mendel took monastic vows at age 21 for reasons including solving financial difficulties and access to knowledge. Due to the restrictions imposed by his chosen path, he accepted celibacy, and the concept of personal life was absent for him. In the Catholic tradition, clergy keep a vow of celibacy, so Mendel did not have a wife or children.

At the age of 25, he became a priest in the Augustinian monastery of St. Thomas, which was the cultural and scientific center of the region. Abbot Cyril Knapp encouraged his brethren's interest in science, and the monks supervised the education of schoolchildren in the surrounding areas. Mendel also enjoyed teaching children and was a favorite teacher. In the monastery garden he conducted his now famous hybridization experiments.

In 1868, after the death of his spiritual mentor Napp, Mendel took the post of abbot of the Starobrnensky (Augustinsky) Monastery. From that same year, large-scale scientific searches ended, giving way to worries about the entrusted holy place. Gregor was engaged in administrative work and entered into controversy with the secular authorities for the introduction of additional taxes for religious institutions. He held the post until the end of his life.

Death

Abbot Mendel died in 1884 due to chronic nephritis, at the age of 61. On the site of the abbey, which served for almost 40 years, a museum named after him was later opened. The grave is located in Brno. It is crowned with a monument with the words belonging to the monk:

"My time will come."

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

Gregor Mendel was born July 22, 1822, Heinzendorf, Austria-Hungary, now Ginczyce. Died January 6, 1884, Brunn, now Brno, Czech Republic.

Difficult years of study

Johann was born the second child into a peasant family of mixed German-Slavic origin and middle income, to Anton and Rosina Mendel. In 1840, Mendel graduated from six classes at the gymnasium in Troppau (now Opava) and the following year entered philosophy classes at the university in Olmutz (now Olomouc). However, the family's financial situation worsened during these years, and from the age of 16 Mendel himself had to take care of his own food. Unable to constantly endure such stress, Mendel, after graduating from philosophical classes, in October 1843, entered the Brunn Monastery as a novice (where he received the new name Gregor). There he found patronage and financial support for further studies.

In 1847 Mendel was ordained a priest. At the same time, from 1845, he studied for 4 years at the Brunn Theological School. Augustinian monastery of St. Thomas was the center of scientific and cultural life in Moravia. In addition to a rich library, he had a collection of minerals, an experimental garden and a herbarium. The monastery patronized school education in the region.

Monk teacher

As a monk, Gregor Mendel enjoyed teaching physics and mathematics classes at a school in the nearby town of Znaim, but failed the state teacher certification exam. Seeing his passion for knowledge and high intellectual abilities, the abbot of the monastery sent him to continue his studies at the University of Vienna, where Mendel studied as an undergraduate for four semesters in the period 1851-53, attending seminars and courses in mathematics and natural sciences, in particular, the course of the famous physics K. Doppler. Good physical and mathematical training later helped Mendel in formulating the laws of inheritance. Returning to Brunn, Mendel continued teaching (he taught physics and natural history at a real school), but his second attempt to pass teacher certification was again unsuccessful.

Experiments on pea hybrids

Since 1856, Gregor Mendel began to conduct well-thought-out extensive experiments in the monastery garden (7 meters wide and 35 meters long) on crossing plants (primarily among carefully selected pea varieties) and elucidating the patterns of inheritance of traits in the offspring of hybrids. In 1863 he completed the 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 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 by 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.

Secondly, Gregor Mendel formulated two basic principles, or laws of inheritance of traits over a series of 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 20th century based on the ideas of Mendel.

Great discoveries are often not immediately recognized

Although the proceedings of the Society, where Mendel's article was published, were received in 120 scientific libraries, and Mendel sent out an additional 40 reprints, his work had only one favorable response - from K. Nägeli, a professor of botany from Munich. Nägeli himself worked on hybridization, introduced the term “modification” and put forward a speculative theory of heredity. However, he doubted that the laws identified on peas were universal and advised repeating the experiments on other species. Mendel respectfully agreed to this. But his attempt to repeat the results obtained on peas on the hawkweed, with which Nägeli worked, was unsuccessful. Only decades later it became clear why. Seeds in hawkweed are formed parthenogenetically, without the participation of sexual reproduction. There were other exceptions to Gregor Mendel's principles that were interpreted much later. This is partly the reason for the cold reception of his work. 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.

A beautiful myth has been created around the paradoxical fate of the discovery and rediscovery of Mendel’s laws that his work remained completely unknown and was only discovered by chance and independently, 35 years later, by three rediscoverers. In fact, Mendel's work was cited about 15 times in an 1881 summary of plant hybrids, and botanists knew about it. Moreover, as it turned out when analyzing the workbooks of K. Correns, back in 1896 he read Mendel’s article and even wrote an abstract of it, but did not understand its deep meaning at that time and forgot.

The style of conducting experiments and presenting the results in Mendel’s classic article makes it very likely the assumption that the English mathematical statistician and geneticist R. E. Fisher came to in 1936: Mendel first intuitively penetrated into the “soul of facts” and then planned a series of many years of experiments so that the insight his idea came to light in the best possible way. The beauty and rigor of the numerical ratios of forms during splitting (3: 1 or 9: 3: 3: 1), the harmony into which it was possible to fit the chaos of facts in the field of hereditary variability, the ability to make predictions - all this internally convinced Mendel of the universal nature of what he found on pea laws. All that remained was to convince the scientific community. But this task is as difficult as the discovery itself. After all, knowing the facts does not mean understanding them. A major discovery is always associated with personal knowledge, feelings of beauty and wholeness based on intuitive and emotional components. It is difficult to convey this non-rational type of knowledge to other people, because it requires effort and the same intuition on their part.

The fate of Mendel's discovery - a delay of 35 years between the very fact of the discovery and its recognition in the community - is not a paradox, but rather the norm in science. Thus, 100 years after Mendel, already in the heyday of genetics, a similar fate of non-recognition for 25 years befell the discovery of mobile genetic elements by B. McClintock. And this despite the fact that, unlike Mendel, at the time of her discovery she was a highly respected scientist and a member of the US National Academy of Sciences.

In 1868, Gregor Mendel was elected abbot of the monastery and practically retired from scientific pursuits. His archive contains notes on meteorology, beekeeping, and linguistics. On the site of the monastery in Brno, the Mendel Museum has now been created; a special magazine “Folia Mendeliana” is published.

More about Gregor Mendel from another source:

The Austro-Hungarian scientist Gregor Mendel is rightfully considered the founder of the science of heredity - genetics. The researcher’s work, “rediscovered” only in 1900, brought posthumous fame to Mendel and served as the beginning of a new science, which was later called genetics. Until the end of the seventies of the 20th century, genetics mainly moved along the path paved by Mendel, and only when scientists learned to read the sequence of nucleic bases in DNA molecules, heredity began to be studied not by analyzing the results of hybridization, but relying on physicochemical methods.

In elementary school, Gregor Mendel showed outstanding mathematical abilities and, at the insistence of his teachers, continued his education at the gymnasium of the small nearby town of Opava. However, there was not enough money in the family for Mendel’s further education. With great difficulty they managed to scrape together enough to complete the gymnasium course. The younger sister Teresa came to the rescue: she donated the dowry that had been saved for her. With these funds, Mendel was able to study for some more time in university preparation courses. After this, the family's funds dried up completely.

A solution was suggested by mathematics professor Franz. He advised Mendel to join the Augustinian monastery in Brno. It was headed at that time by Abbot Cyril Napp, a man of broad views who encouraged the pursuit of science. In 1843, Mendel entered this monastery and received the name Gregor (at birth he was given the name Johann). Four years later, the monastery sent the twenty-five-year-old monk Mendel as a teacher in a secondary school. Then, from 1851 to 1853, he studied natural sciences, especially physics, at the University of Vienna, after which he became a teacher of physics and natural history at the real school in Brno.

His teaching activity, which lasted fourteen years, was highly appreciated by both the school management and students. According to the latter’s recollections, he was considered one of their favorite teachers. For the last fifteen years of his life, Gregor Mendel was the abbot of the monastery.

From his youth, Gregor was interested in natural history. More of an amateur than a professional biologist, Mendel constantly experimented with various plants and bees. In 1856 he began his classic work on hybridization and the analysis of the inheritance of characters in peas.

Gregor Mendel worked in a tiny, less than two and a half hundred hectares, monastery garden. He sowed peas for eight years, manipulating two dozen varieties of this plant, different in flower color and seed type. He did ten thousand experiments. With his diligence and patience, he greatly amazed his partners, Winkelmeyer and Lilenthal, who helped him in necessary cases, as well as the gardener Maresh, who was very prone to drinking. If Mendel gave explanations to his assistants, it is unlikely that they could understand him.

Life flowed slowly in the monastery of St. Thomas. Gregor Mendel was also leisurely. Persistent, observant and very patient. Studying the shape of seeds in plants obtained as a result of crossings, in order to understand the patterns of transmission of only one trait (“smooth - wrinkled”), he analyzed 7324 peas. He examined each seed through a magnifying glass, comparing their shape and making notes.

With the experiments of Gregor Mendel, another countdown of time began, the main distinguishing feature of which was, again, the hybridological analysis introduced by Mendel of the heredity of individual characteristics of parents in the offspring. It is difficult to say what exactly made the natural scientist turn to abstract thinking, distract himself from bare numbers and numerous experiments. But it was precisely this that allowed the modest teacher of the monastery school to see the holistic picture of the research; see it only after having to neglect the tenths and hundredths due to inevitable statistical variations. Only then, the alternative characteristics literally “labeled” by the researcher revealed something sensational to him: certain types of crossing in different offspring give a ratio of 3:1, 1:1, or 1:2:1.

Gregor Mendel turned to the work of his predecessors for confirmation of his guess. Those whom the researcher respected as authorities came at different times and each in his own way to the general conclusion: genes can have dominant (suppressive) or recessive (suppressed) properties. And if so, Mendel concludes, then the combination of heterogeneous genes gives the same splitting of characters that is observed in his own experiments. And in the very ratios that were calculated using his statistical analysis. “Checking the harmony with algebra” of the ongoing changes in the resulting generations of peas, the scientist even introduced letter designations, marking the dominant state with a capital letter and the recessive state of the same gene with a lowercase letter.

G. Mendel proved that each characteristic of an organism is determined by hereditary factors, inclinations (later they were called genes), transmitted from parents to offspring with germ cells. As a result of crossing, new combinations of hereditary characteristics may appear. And the frequency of occurrence of each such combination can be predicted.

Summarized, the results of the scientist’s work look like this:

All first generation hybrid plants are the same and exhibit the trait of one of the parents;
- among the second generation hybrids, plants with both dominant and recessive traits appear in a ratio of 3:1;
- two traits behave independently in the offspring and are found in all possible combinations in the second generation;
- it is necessary to distinguish between traits and their hereditary inclinations (plants exhibiting dominant traits may, in a latent form, carry recessive inclinations);
- the union of male and female gametes is random in relation to the makings of what characteristics these gametes carry.

In February and March 1865, in two reports at meetings of the provincial scientific circle, called the Society of Naturalists of the city of Bru, one of its ordinary members, Gregor Mendel, reported the results of his many years of research, completed in 1863. Despite the fact that his reports were received rather coldly by members of the circle, he decided to publish his work. It was published in 1866 in the works of the society entitled “Experiments on plant hybrids.”

Contemporaries did not understand Mendel and did not appreciate his work. For many scientists, refuting Mendel’s conclusion would mean nothing less than affirming their own concept, which states that an acquired trait can be “squeezed” into a chromosome and turned into an inherited one. As much as venerable scientists did not crush the “seditious” conclusion of the modest abbot of the monastery from Brno, they came up with all kinds of epithets in order to humiliate and ridicule. But time decided in its own way.

Gregor Mendel was not recognized by his contemporaries. The scheme seemed too simple and ingenuous to them, into which complex phenomena, which in the minds of mankind constituted the foundation of the unshakable pyramid of evolution, fit without pressure or creak. In addition, Mendel's concept also had vulnerabilities. That's how it seemed to his opponents, at least. And the researcher himself, too, since he could not dispel their doubts. One of the “culprits” of his failures was the hawk.

Botanist Karl von Naegeli, a professor at the University of Munich, having read Mendel’s work, suggested that the author test the laws he discovered on the hawkweed. This small plant was Naegeli's favorite subject. And Mendel agreed. He spent a lot of energy on new experiments. Hawkweed is an extremely inconvenient plant for artificial crossing. Very small. I had to strain my vision, but it began to deteriorate more and more. The offspring resulting from the crossing of the hawkweed did not obey the law, as he believed, to be correct for everyone. Only years later, after biologists established the fact of other, non-sexual reproduction of the hawksbill, the objections of Professor Naegeli, Mendel's main opponent, were removed from the agenda. But neither Mendel nor Nägeli himself, alas, were alive anymore.

The greatest Soviet geneticist, Academician B.L., spoke very figuratively about the fate of Mendel’s work. Astaurov, first president of the All-Union Society of Genetics and Breeders named after Nikolai Ivanovich Vavilov: “The fate of Mendel’s classic work is perverse and is not alien to drama. Although he discovered, clearly demonstrated and largely understood very general patterns of heredity, the biology of that time had not yet matured to realize their fundamental nature. Gregor Mendel himself, with amazing insight, foresaw the general validity of the patterns discovered on peas and received some evidence of their applicability to some other plants (three types of beans, two types of gillyflower, corn and night beauty). However, his persistent and tedious attempts to apply the discovered patterns to the crossing of numerous varieties and species of hawkweed did not live up to expectations and suffered a complete fiasco. As happy as the choice of the first object (peas) was, the second was just as unsuccessful. Only much later, already in our century, it became clear that the peculiar patterns of inheritance of characteristics in the hawksbill are an exception that only confirms the rule.

In Mendel's time, no one could suspect that the crossings he undertook between varieties of hawkweed actually did not occur, since this plant reproduces without pollination and fertilization, in a virgin way, through the so-called apogamy. The failure of painstaking and intense experiments, which caused almost complete loss of vision, the burdensome duties of a prelate that fell on Mendel and his advancing years forced him to stop his favorite research.

A few more years passed, and Gregor Mendel passed away, not foreseeing what passions would rage around his name and what glory it would ultimately be covered with. Yes, fame and honor will come to Mendel after his death. He will leave life without unraveling the secret of the hawk, which did not “fit” into the laws he derived for the uniformity of first-generation hybrids and the splitting of characteristics in the offspring.”

It would have been much easier for Mendel if he had known about the work of another scientist, Adams., who by that time had published a pioneering work on the inheritance of traits in humans. But Mendel was not familiar with this work. But Adams, on the basis of empirical observations of families with hereditary diseases, actually formulated the concept of hereditary inclinations, noting the dominant and recessive inheritance of traits in humans. But botanists had not heard about the work of a doctor, and he probably had so much practical medical work to do that there was simply not enough time for abstract thoughts. In general, one way or another, geneticists learned about Adams’ observations only when they began seriously studying the history of human genetics.

Mendel was also unlucky. Too early, the great researcher reported his discoveries to the scientific world. The latter was not ready for this yet. Only in 1900, with the rediscovery of Mendel's laws, the world was amazed at the beauty of the logic of the researcher's experiment and the elegant accuracy of his calculations. And although the gene continued to remain a hypothetical unit of heredity, doubts about its materiality were finally dispelled.

Gregor Mendel was a contemporary of Charles Darwin. But the Brunn monk’s article did not catch the eye of the author of “The Origin of Species.” One can only guess how Darwin would have appreciated Mendel's discovery if he had become acquainted with it. Meanwhile, the great English naturalist showed considerable interest in plant hybridization. Crossing different forms of snapdragon, he wrote about the splitting of hybrids in the second generation: “Why is this so. God knows..."

Gregor Mendel died January 6, 1884, abbot of the monastery where he conducted his experiments with peas. Unnoticed by his contemporaries, Mendel, however, did not waver in his rightness. He said:

"My time will come." These words are inscribed on his monument, installed in front of the monastery garden where he conducted his experiments.

The famous physicist Erwin Schrödinger believed that the application of Mendel's laws was tantamount to the introduction of quantum principles in biology.

The revolutionary role of Mendelism in biology became increasingly obvious. By the early thirties of our century, genetics and Mendel's underlying laws became the recognized foundation of modern Darwinism. Mendelism became the theoretical basis for the development of new high-yielding varieties of cultivated plants, more productive breeds of livestock, and beneficial species of microorganisms. Mendelism gave impetus to the development of medical genetics...

In the Augustinian monastery on the outskirts of Brno, a memorial plaque was erected, and a beautiful marble monument to Gregor Mendel was erected next to the front garden. The rooms of the former monastery, overlooking the front garden where Mendel conducted his experiments, have now been turned into a museum named after him. Here are collected manuscripts (unfortunately, some of them were lost during the war), documents, drawings and portraits related to the life of the scientist, books that belonged to him with his notes in the margins, a microscope and other instruments that he used, as well as those published in different countries books dedicated to him and his discovery.

At the beginning of the 19th century, in 1822, in Austrian Moravia, in the village of Hanzendorf, a boy was born into a peasant family. He was the second child in the family. At birth he was named Johann, the surname of his father was Mendel.

Life was not easy, the child was not spoiled. Since childhood, Johann got used to peasant work and fell in love with it, especially gardening and beekeeping. How useful were the skills he acquired in childhood?

The boy showed outstanding abilities early. Mendel was 11 years old when he was transferred from a village school to a four-year school in a nearby town. He immediately proved himself there and a year later he ended up in a gymnasium in the city of Opava.

It was difficult for parents to pay for school and support their son. And then misfortune befell the family: the father was seriously injured - a log fell on his chest. In 1840, Johann graduated from high school and, at the same time, from the teacher candidate school. In 1840, Mendel graduated from six classes at the gymnasium in Troppau (now Opava) and the following year entered philosophy classes at the university in Olmutz (now Olomouc). However, the family's financial situation worsened during these years, and from the age of 16 Mendel himself had to take care of his own food. Unable to constantly endure such stress, Mendel, after graduating from philosophical classes, in October 1843, entered the Brunn Monastery as a novice (where he received the new name Gregor). There he found patronage and financial support for further studies. In 1847 Mendel was ordained a priest. At the same time, from 1845, he studied for 4 years at the Brunn Theological School. Augustinian monastery of St. Thomas was the center of scientific and cultural life in Moravia. In addition to a rich library, he had a collection of minerals, an experimental garden and a herbarium. The monastery patronized school education in the region.

Despite the difficulties, Mendel continues his studies. Now in philosophy classes in the city of Olomeuc. Here they teach not only philosophy, but also mathematics and physics - subjects without which Mendel, a biologist at heart, could not imagine his future life. Biology and mathematics! Nowadays this combination is inextricable, but in the 19th century it seemed absurd. It was Mendel who was the first to continue the broad track of mathematical methods in biology.

He continues to study, but life is hard, and then the days come when, by Mendel’s own admission, “I can’t bear such stress any longer.” And then a turning point comes in his life: Mendel becomes a monk. He does not at all hide the reasons that pushed him to take this step. In his autobiography he writes: “I found myself forced to take a position that freed me from worries about food.” Frankly, isn't it? And not a word about religion or God. An irresistible craving for science, a desire for knowledge, and not at all a commitment to religious doctrine led Mendel to the monastery. He turned 21 years old. Those who became monks took a new name as a sign of renunciation from the world. Johann became Gregor.

There was a period when he was made a priest. A very short period. Comfort the suffering, equip the dying for their final journey. Mendel didn't really like it. And he does everything to free himself from unpleasant responsibilities.

Teaching is a different matter. As a monk, Mendel enjoyed teaching physics and mathematics classes at a school in the nearby town of Znaim, but failed the state teacher certification exam. Seeing his passion for knowledge and high intellectual abilities, the abbot of the monastery sent him to continue his studies at the University of Vienna, where Mendel studied as an undergraduate for four semesters in the period 1851-53, attending seminars and courses in mathematics and natural sciences, in particular, the course of the famous physics K. Doppler. Good physical and mathematical training later helped Mendel in formulating the laws of inheritance. Returning to Brunn, Mendel continued teaching (he taught physics and natural history at a real school), but his second attempt to pass teacher certification was again unsuccessful.

Interestingly, Mendel took the exam to become a teacher twice and... failed twice! But he was a very educated man. There is nothing to say about biology, of which Mendel soon became a classic; he was a highly gifted mathematician, loved physics very much and knew it very well.

Failures in exams did not interfere with his teaching activities. At the Brno City School, Mendel the teacher was highly valued. And he taught without a diploma.

There were years in Mendel's life when he became a recluse. But he did not bow his knees before the icons, but... before the beds of peas. Since 1856, Mendel began to conduct well-thought-out extensive experiments in the monastery garden (7 meters wide and 35 meters long) on crossing plants (primarily among carefully selected pea varieties) and elucidating the patterns of inheritance of traits in the offspring of hybrids. In 1863 he completed the experiments and in 1865, at two meetings of the Brunn Society of Natural Scientists, he reported the results of his work. From morning until evening he worked in the small monastery garden. Here, from 1854 to 1863, Mendel conducted his classical experiments, the results of which are not outdated to this day. G. Mendel also owes his scientific successes to his unusually successful choice of research object. In total, he examined 20 thousand descendants in four generations of peas.

Experiments on crossing peas have been going on for about 10 years. Every spring, Mendel planted plants on his plot. The report “Experiments on plant hybrids,” which was read to Brune naturalists in 1865, came as a surprise even to friends.

Peas were convenient for various reasons. The offspring of this plant have a number of clearly distinguishable characteristics - green or yellow color of cotyledons, smooth or, on the contrary, wrinkled seeds, swollen or constricted beans, long or short stem axis of the inflorescence, and so on. There were no transitional, half-hearted “blurred” signs. Each time one could confidently say “yes” or “no”, “either-or”, and deal with the alternative. And therefore there was no need to challenge Mendel’s conclusions, to doubt them. And all the provisions of Mendel’s theory were no longer refuted by anyone and deservedly became part of the golden fund of science.

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 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 by 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 different 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 20th century based on the ideas of Mendel.

The fate of Mendel's discovery - a delay of 35 years between the very fact of the discovery and its recognition in the community - is not a paradox, but rather a norm in science. Thus, 100 years after Mendel, already in the heyday of genetics, a similar fate of non-recognition for 25 years befell the discovery of mobile genetic elements by B. McClintock. And this despite the fact that, unlike Mendel, at the time of her discovery she was a highly respected scientist and a member of the US National Academy of Sciences.

In 1868, Mendel was elected abbot of the monastery and practically retired from scientific pursuits. His archive contains notes on meteorology, beekeeping, and linguistics. On the site of the monastery in Brno, the Mendel Museum has now been created; A special magazine "Folia Mendeliana" is published.