A monk of Czech origin, Gregor Mendel, conducted experiments in the years 1856-1866, which later became widely known. As a result of his research, a new science was born - genetics. The fundamental factor for its development was the First Law of Mendel. Garden pea was chosen as a prototype. This was due to the presence of many varieties that have clear differences among themselves according to certain characteristics. In addition, these plants are easily grown and crossed. As a result of careful planning of the experiments, their careful conduct, as well as the implementation of a large number of laboratory experiments, reliable statistical information was obtained. As a result, the First Law of Mendel was first discovered, and then the subsequent ones.
The essence of the experiments
So, in more detail about how the First Law of Mendel was discovered. At the beginning of the study, plants were selected that had obvious differences in any pair of characters: for example, in the arrangement of flowers - apical or axillary. Growing each type for several generations, Mendel noted their suitability for experimental use. The experiments consisted of crossing by transferring pollen from one plant to another. Reliable experimental results were obtained due to the careful observance of a number of precautions. In particular, the stamens of the flowers that were pollinated were subsequently removed, special caps were put on the flowers to prevent the transfer of pollen from other plants.
The results of the experiments
From all seeds collected from hybrids, plants with axillary flowers were obtained in all cases.
This feature has become dominant. The presence of apical flowers was taken as a recessive trait. After the experiment, plants of the first generation were left for selfing. The resulting hybrids had part of axillary and part of apical flowers. According to Mendel, the second type was present in the first generation. However, the severity of this symptom was insufficient. That is, it manifested itself in a hidden form. When conducting similar experiments with any pair of characters, approximately three quarters of the hybrids had characteristics that appeared in the first generation. A fourth of the offspring in the 2nd family of hatched plants possessed properties that were not identified in the 1st. The more experiments were carried out, the more the result approached the ratio 3: 1. As a result of these studies, the First Mendel Law was derived.
conclusions
In studying the characteristics of crossed plants — two similar characteristics were present in the parental specimens — hybrids received one of the hereditary factors. At the same time, the properties of the first generation in the offspring did not merge, but retained individuality. As a result of the research, reliable information was collected so that the First Law of Mendel was derived. Its wording is as follows: “The attributes of a certain organism are determined by a pair of internal factors (genes). In the second generation, obtained from monohybrid crossbreeding, approximately a quarter of the descendants have recessive traits. ” It should be noted that the First and Second Mendel Laws were not first accepted by the scientific community. Subsequently, in the works of other scientists, these provisions were proved again. As a result of new research, a chromosome theory of heredity was formed .