People have always been interested in patterns.trait inheritance. Why do children resemble their parents? Is there a risk of transmission of hereditary diseases? These and many other questions remained under a veil of secrecy until the XIX century. It was then that Mendel managed to accumulate all the accumulated knowledge on this topic, as well as to establish specific patterns through complex analytical experiments.
The main patterns of inheritance of characters -these are principles according to which certain characteristics are passed from parent organisms to offspring. Their discovery and clear wording is a merit of Gregor Mendel, who conducted numerous experiments on this issue.
The main achievement of the scientist is proofdiscrete nature of hereditary factors. In other words, a specific gene is responsible for each trait. The first maps were built for corn and fruit flies. The latter is a classic object for conducting genetic experiments.
Заслуги Менделя трудно переоценить, о чем говорят and domestic scientists. Thus, the famous geneticist Timofeev-Resovsky noted that Mendel was the first to conduct fundamental experiments and gave an accurate description of phenomena that previously existed at the level of hypotheses. Thus, it can be considered a pioneer of mathematical thinking in the field of biology and genetics.
Стоит отметить, что закономерности наследования signs by Mendel were not formulated from scratch. His research was based on the research of predecessors. It is worth especially to note the following scientists:
Thus, by the XIX century suchphenomena like dominance, uniformity of the first generation, as well as combinatorics of traits in subsequent hybrids. Nevertheless, no general laws were worked out. It is the analysis of the available information and the development of a reliable research methodology that are the main achievements of Mendel.
The patterns of inheritance of traits according to Mendel were formulated as a result of fundamental research. The activities of the scientist was carried out as follows:
Considering patterns of inheritancesigns, it is worth paying special attention to the uniformity of hybrids of the first generation. It was discovered through experience, during which the parental forms were crossed with one contrasting sign (form, color, etc.).
Mendel decided to holdAn experiment on two pea varieties - with red and white flowers. As a result, hybrids of the first generation received purple inflorescences. Thus, there is reason to talk about the presence of dominant and recessive traits.
Стоит отметить, что данный опыт Менделя был не the only one. He used for experiments plants with different shades of inflorescences, with different shape of fruits, different stem height and other options. Experimentally, he was able to prove that all hybrids of the first order are uniform and characterized by a dominant trait.
В ходе изучения такого вопроса, как patterns of inheritance of traits, experiments were conducted both on plants and on living organisms. Thus, it was possible to establish that the signs are not always in a relationship of complete domination and suppression. For example, when crossing chickens of black and white color, it was possible to get gray offspring. It was the same with some plants, when varieties with purple and white flowers gave pink shades at the exit. Thus, it is possible to correct the first principle, indicating that the first generation of hybrids will have the same characteristics, while they may be intermediate.
Continuing to explore patterns of inheritancesigns, Mendel found it necessary to cross the two descendants of the first generation (heterozygous). As a result, offspring was obtained, part of which bore the dominant trait, and the other - recessive. From this we can conclude that the secondary trait in the first generation of hybrids does not disappear at all, but is only suppressed and may well appear in subsequent offspring.
Many questions raise patternstrait inheritance. The experiments of Mendel also touched individuals, which differ from each other at once on several grounds. For each separately, the previous patterns were respected. But now, considering the totality of features, it was not possible to identify any patterns between their combinations. Thus, there is reason to talk about the independence of inheritance.
Some patterns of inheritance of traitsestablished by Mendel, were purely hypothetical. We are talking about the law of purity of gametes, which consists in the fact that only one allele from a pair contained in the gene of the parent individual enters them.
At the time of Mendel there was no technical means.to confirm this hypothesis. Nevertheless, the scientist was able to formulate a general statement. Its essence lies in the fact that in the process of the formation of hybrids, hereditary characteristics remain unchanged, and not mixed.
Genetics is a science that studies patterns.trait inheritance. Mendel made a significant contribution to its development by developing the fundamental provisions on this issue. However, in order for them to be fulfilled, the following essential conditions must be met:
It should be noted that most of the living organisms, including humans, correspond to these characteristics.
Despite the fact that initially genetic principles were studied using plants as an example, for animals and humans they are also valid. It is worth noting the following types of inheritance:
In order to understand how the patterns of inheritance of Mendel signs and other genetic processes work, you should familiarize yourself with the basic definitions and concepts. These include the following:
Mendel formulated and proved in practicebasic patterns of inheritance of characters. Their description is given on the example of plants and slightly simplified. But in practice it is fair for all living organisms.
