Biography of Gregor Mendel | Monk and botanist.
(Johann Gregor or Gregorio Mendel; Heizendorf, today Hyncice, current Czech Republic, 1822 - Brunn, now Brno, id., 1884) monk and Austrian botanist who formulated the biological inheritance laws that bear his name; his experiments on the phenomena of inheritance in the peas are the starting point of modern genetics.
Gregor MendelHis father was a veteran of the Napoleonic wars, and his mother, the daughter of a gardener. After a childhood marked by poverty and hardship, in 1843 Johann Mendel joined the monastery of Augustinian Konigskloster, near Brünn, where it took the name of Gregor and was ordained priest in 1847.
He lived in the Abbey of Santo Tomás (Brünn), and to follow the teaching career, he was sent to Vienna, where earned a doctorate in mathematics and Sciences (1851). In 1854 Mendel became Deputy Professor of the Royal School of Brunn, and in 1868 was appointed Abbot of the monastery, which abandoned definitively scientific research and dedicated himself exclusively to the own tasks of its function.
The core of their work (which began in the year 1856 from crossbreeding experiments with peas in the garden of the monastery) allowed him to discover the three laws of inheritance or laws of Mendel, thanks to which it is possible to describe the mechanisms of inheritance and that would be explained later by the father of modern experimental genetics , Thomas Hunt Morgan (1866-1945) American biologist.
In the 18th century had already developed a number of important studies on plant hybridization, among which highlighted the carried out by Kölreuter, W. Herbert, C. C. Sprengel and A. Knight, and already in the 19th century, Gartner and Sageret (1825). The culmination of all these works was conducted, on the one hand, of ch. Naudin (1815-1899) and, on the other hand, Gregor Mendel, who went further than Naudin.
The three laws discovered by Mendel are set out as follows: according to the first, when two pure varieties of the same species, cross the descendants are all the same; the second says that cross each other second-generation hybrids, descendants become divided in four parts, of which three inherit called a dominant and a recessive; Finally, the third law concludes that, where starting two varieties differ in two or more characters, each one of them is transmitted independently of others.
To carry out their work, Mendel chose not species, but well-established self-fertilized species breeds Pisum sativum. The first phase of the experiment consisted in the obtaining (through previous conventional crops) constant pure lines and pick up methodical way part of the seed produced by each plant. He then crossed these strains, two to two, using the technique of artificial pollination. In this way it was possible to combine, two by two, different varieties which are very precise differences between itself (lisas-semillas wrinkled seeds, flowers white-colored flowers, etc.).
Gregor MendelThe analysis of the obtained results allowed Mendel concluded that, through the crossing of races which differ in at least two characters, new stable races (homozygous new combinations) can be created. While he referred his work with peas to the highest authority of his time on issues of biology, W. von Nägeli, his research did not receive recognition until the rediscovery of the laws of inheritance by Hugo de Vries, Carl E. Correns and E. Tschernack von Seysenegg, who, with more than thirty years of delay, and after reviewing most of the existing literature on the subject they were attributed to Johan Gregor Mendel, the priority of discovery.
Mendel's laws
The Mendelian laws of inheritance established the way in which certain characters of organic beings in a generation are transmitted to another. Mendel formulated these laws from a series of experiments between 1856 and 1865 which consisted in crossing two varieties of peas and studying specific features: the color and the location of flowers in plant, shape and color of pea pods, the shape and color of seeds and the length of the stems of plants.
The method used by Mendel was to transfer the pollen (male sexual cells) of the Stamen (male reproductive organ) of a plant of peas to the pistil (female reproductive organ) of a second plant of peas. As an example of these experiments, suppose that collects pollen from a plant of peas with red blossoms and fertile with a plant of peas with white flowers. The aim of Mendel was to know what color would be the offspring of these two plants flowers.
In a second series of experiments, Mendel studied the changes that occurred in the second generation. I.e. Suppose that two descendents of the first crossing Cross Red/white. What color would have flowers in this second generation of plants? As a result of his research, Mendel defined three general laws the way they are transmitted traits from one generation to the next in the pea plants.
The first law of Mendel is called law of dominant characters or the uniformity of the first filial generation hybrids. If a pure line of peas from smooth seed with another rugged seed, individuals of the first filial generation or F1 crosses are all uniform; in this case they seem to everyone to one of the parents, of smooth seed. The same Mendel called dominant character that prevails in the hybrid and recessive that manifests itself in it. Then was that the dominance is common but not universal. Many times there are intermediate, inheritance because hybrids have a medial aspect. In other cases, the situation is codominance.
The second law is the law of segregation. If the hybrids of the first filial generation seeds are planted (F1) and is left to you to autofecunden, you get the second filial generation or F2, can be seen that the ratio between smooth and rough is 3:1, in the case of monohybridism with dominance. Put another way, appear in next generation three-fourths of the descent with a dominant (smooth seed) and a quarter with the recessive character (wrinkled seed). There are three types of individuals similar to a parent, in the proportion of 1:2:1 in cases of monohybridism with intermediate inheritance and codominance.
Second law of Mendel: dominance (left) and with intermediate inheritance (r)At the time of Mendel was not known molecular biology; What today is called gene is what Mendel once called hereditary factor: a biological unit responsible for the transmission of genetic traits. Mendel meant that the alternate characters are determined by these "heredity", that is transmitted through the gametes, and that each factor can exist in two alternative forms or alleles (smooth/rough, red/white...); It also meant that each individual has two genes for each character. It is called homozygous to the individual who has two identical alleles for a particular character, and heterozygosity has them different. The reappearance of the characters of the parents in the second generation, Mendel concluded the law of, segregation which postulates that the two factors (genes) for each character do not mix or merge in any way, but that they secrete at the time of the formation of the gametes.
The third law, called law of independent transmission or the independence of the characters, postulated that genes for different traits are inherited independently. It can serve as illustration the experiment in which Mendel crossed smooth and yellow seeds plants and rough seeds and green plants. After a first filial generation in which all hybrid individuals are uniform because they repeat the characteristics of the dominant double parent, the second generation is made up of four kinds of individuals (smooth and yellow, smooth and green, yellow, and rough and rugged and green) in a ratio of 9:3:3: 1. This law is derived from the fact that Mendel studied, without knowing it, free characters; It has universal value, because many characters are linked to others and their segregation is not independent, as you can see for the different characters that encloses a same chromosome.
The application of the three laws of Mendel allows to predict the characteristics that the offspring of parents of known genetic composition will present. Suppose a plant of peas in which both alleles of the gene for flower color carry the Red code. A way to represent this situation is to write RR, which indicates that both alleles (R & R) have red color code. However, another gene could have a different mix of alleles, as in Rr. In this case, R stands for red, and r "non-red", or what is the same, "white"; the flower will be red because, by the first law, the dominant character is imposed on the recessive.
Let's look at the cross between a plant of peas with red flowers (RR) and one with white flowers (rr). By the second Act, the genes of both parents (RR and rr) dividers to produce the corresponding alleles, which can be combined in four different ways. However, the four combinations produce the same result: Rr. R being the dominant character, the four plants will have red flowers. Despite this, the situation has changed: the new gen of this first filial generation consists of one allele for Red (R) and one allele for the Red "no" (r). The genes of the parents were RR and rr; the genes of all children are Rr.
When two floors of this first filial generation (Rr and Rr), intersect once again, the alleles of each plant are separated one from the other, and, once more, the alleles can still recombine in four different ways, but, in this case, the results are different from those obtained in the first generation. The possible results are two combinations Rr, a combination RR and rr combination. R is dominant over r, three of the four combinations will produce plants with red flowers, and a (rr option) will produce plants with no red flowers (white).
After his period scientific advances have shown that Mendel inheritance laws constitute a simplification of processes that often are much more complex than the provided examples. However, these laws still serve as the Foundation for the science of genetics, which would have been not born without the discoveries of Mendel. Method that verified his experiments was rigorous, and served as a model also to investigations that in large numbers would be developed in this field.
Gregor Mendel
He lived in the Abbey of Santo Tomás (Brünn), and to follow the teaching career, he was sent to Vienna, where earned a doctorate in mathematics and Sciences (1851). In 1854 Mendel became Deputy Professor of the Royal School of Brunn, and in 1868 was appointed Abbot of the monastery, which abandoned definitively scientific research and dedicated himself exclusively to the own tasks of its function.
The core of their work (which began in the year 1856 from crossbreeding experiments with peas in the garden of the monastery) allowed him to discover the three laws of inheritance or laws of Mendel, thanks to which it is possible to describe the mechanisms of inheritance and that would be explained later by the father of modern experimental genetics , Thomas Hunt Morgan (1866-1945) American biologist.
In the 18th century had already developed a number of important studies on plant hybridization, among which highlighted the carried out by Kölreuter, W. Herbert, C. C. Sprengel and A. Knight, and already in the 19th century, Gartner and Sageret (1825). The culmination of all these works was conducted, on the one hand, of ch. Naudin (1815-1899) and, on the other hand, Gregor Mendel, who went further than Naudin.
The three laws discovered by Mendel are set out as follows: according to the first, when two pure varieties of the same species, cross the descendants are all the same; the second says that cross each other second-generation hybrids, descendants become divided in four parts, of which three inherit called a dominant and a recessive; Finally, the third law concludes that, where starting two varieties differ in two or more characters, each one of them is transmitted independently of others.
To carry out their work, Mendel chose not species, but well-established self-fertilized species breeds Pisum sativum. The first phase of the experiment consisted in the obtaining (through previous conventional crops) constant pure lines and pick up methodical way part of the seed produced by each plant. He then crossed these strains, two to two, using the technique of artificial pollination. In this way it was possible to combine, two by two, different varieties which are very precise differences between itself (lisas-semillas wrinkled seeds, flowers white-colored flowers, etc.).
Gregor Mendel
Mendel's laws
The Mendelian laws of inheritance established the way in which certain characters of organic beings in a generation are transmitted to another. Mendel formulated these laws from a series of experiments between 1856 and 1865 which consisted in crossing two varieties of peas and studying specific features: the color and the location of flowers in plant, shape and color of pea pods, the shape and color of seeds and the length of the stems of plants.
The method used by Mendel was to transfer the pollen (male sexual cells) of the Stamen (male reproductive organ) of a plant of peas to the pistil (female reproductive organ) of a second plant of peas. As an example of these experiments, suppose that collects pollen from a plant of peas with red blossoms and fertile with a plant of peas with white flowers. The aim of Mendel was to know what color would be the offspring of these two plants flowers.
In a second series of experiments, Mendel studied the changes that occurred in the second generation. I.e. Suppose that two descendents of the first crossing Cross Red/white. What color would have flowers in this second generation of plants? As a result of his research, Mendel defined three general laws the way they are transmitted traits from one generation to the next in the pea plants.
The first law of Mendel is called law of dominant characters or the uniformity of the first filial generation hybrids. If a pure line of peas from smooth seed with another rugged seed, individuals of the first filial generation or F1 crosses are all uniform; in this case they seem to everyone to one of the parents, of smooth seed. The same Mendel called dominant character that prevails in the hybrid and recessive that manifests itself in it. Then was that the dominance is common but not universal. Many times there are intermediate, inheritance because hybrids have a medial aspect. In other cases, the situation is codominance.
The second law is the law of segregation. If the hybrids of the first filial generation seeds are planted (F1) and is left to you to autofecunden, you get the second filial generation or F2, can be seen that the ratio between smooth and rough is 3:1, in the case of monohybridism with dominance. Put another way, appear in next generation three-fourths of the descent with a dominant (smooth seed) and a quarter with the recessive character (wrinkled seed). There are three types of individuals similar to a parent, in the proportion of 1:2:1 in cases of monohybridism with intermediate inheritance and codominance.
Second law of Mendel: dominance (left) and with intermediate inheritance (r)
The third law, called law of independent transmission or the independence of the characters, postulated that genes for different traits are inherited independently. It can serve as illustration the experiment in which Mendel crossed smooth and yellow seeds plants and rough seeds and green plants. After a first filial generation in which all hybrid individuals are uniform because they repeat the characteristics of the dominant double parent, the second generation is made up of four kinds of individuals (smooth and yellow, smooth and green, yellow, and rough and rugged and green) in a ratio of 9:3:3: 1. This law is derived from the fact that Mendel studied, without knowing it, free characters; It has universal value, because many characters are linked to others and their segregation is not independent, as you can see for the different characters that encloses a same chromosome.
The application of the three laws of Mendel allows to predict the characteristics that the offspring of parents of known genetic composition will present. Suppose a plant of peas in which both alleles of the gene for flower color carry the Red code. A way to represent this situation is to write RR, which indicates that both alleles (R & R) have red color code. However, another gene could have a different mix of alleles, as in Rr. In this case, R stands for red, and r "non-red", or what is the same, "white"; the flower will be red because, by the first law, the dominant character is imposed on the recessive.
Let's look at the cross between a plant of peas with red flowers (RR) and one with white flowers (rr). By the second Act, the genes of both parents (RR and rr) dividers to produce the corresponding alleles, which can be combined in four different ways. However, the four combinations produce the same result: Rr. R being the dominant character, the four plants will have red flowers. Despite this, the situation has changed: the new gen of this first filial generation consists of one allele for Red (R) and one allele for the Red "no" (r). The genes of the parents were RR and rr; the genes of all children are Rr.
When two floors of this first filial generation (Rr and Rr), intersect once again, the alleles of each plant are separated one from the other, and, once more, the alleles can still recombine in four different ways, but, in this case, the results are different from those obtained in the first generation. The possible results are two combinations Rr, a combination RR and rr combination. R is dominant over r, three of the four combinations will produce plants with red flowers, and a (rr option) will produce plants with no red flowers (white).
After his period scientific advances have shown that Mendel inheritance laws constitute a simplification of processes that often are much more complex than the provided examples. However, these laws still serve as the Foundation for the science of genetics, which would have been not born without the discoveries of Mendel. Method that verified his experiments was rigorous, and served as a model also to investigations that in large numbers would be developed in this field.
Extracted from the website: Biografías y Vidas