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05.10.2021 17:21

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Составить пересказ текста(5-7 предложений) Genetics
Genetics, the study of heredity in general and of genes in particular.
Although the influence of heredity has been recognized since prehistoric times, scientific understanding of inheritance is a fairly recent event. Modern genetics began with the work of Gregor Mendel, an Austrian monk whose breeding experiments with garden peas led him to formulate the basic laws of heredity. Mendel concluded that his plants inherited two factors (one from each parent) for each of the hereditary traits he studied. He further deduced that these factors do not mix in the offspring, that some factors are dominant over others, and that a parent plant randomly transmits one factor from each pair to an offspring.
Mendel published his findings in 1866, but his discoveries were not appreciated by the scientists of his day. By the turn of the century, however, the intellectual climate had changed; in 1900 a number of researchers independently rediscovered Mendel's work and grasped its significance.
The infant science of genetics flowered rapidly. By 1902 Walter Sut-ton of the United States had proposed that chromosomes - major components of the cell nucleus - were the site of Mendel's hereditary factors. The Hardy-Weinberg law, which established the mathematical basis for studying heredity in populations, was independently formulated by the English mathematician Godfrey H. Hardy and the German physician Wilhelm Weinberg in 1908. In 1910 the American genetist Thomas Hunt Morgan began his studies with the fruit fly, Drosophila melanogaster.
Morgan provided evidence not only that genes (as Mendel's factors had come to be called) occur on chromosomes but that those genes lying close together on the same chromosome form linkage groups that tend to be inherited together. He further showed that linkage groups often break apart naturally as a result of a phenomenon called crossing over. During the 1940s, George W. Beadle and Edward L. Tatum of the United States demonstrated that genes exert their influence by directing the production of enzymes, proteins that facilitate chemical reactions in the cell. By 1944 Oswald T. Avery had shown that deoxyribonucelic acid (DNA) was the chromosome component that carried genetic information. About this time Barbara McClintock discovered mobile plant genes that affect heredity. The molecular structure of DNA, however, was not deduced until 1953 by James D. Watson of the United States and Francis H.C. Crick of Great Britain. By 1961 the French genetists Francois Jacob and Jacques Monod had developed a model for the process by which DNA directs protein synthesis in bacterial cells. These developments led to the deciphering of the genetic code of the DNA molecule, which in turn made possible the recombinant DNA techniques that hold immense potential for genetic engineering (q. v.)
Modern genetics studies include population genetics (the study of genetic patterns within populations), classical genetics (how traits are transmitted and expressed), cytogenetics (the mechanics of heredity within the cell), microbial genetics (the heredity of microorganisms), and molecular genetics (the molecular study of genes and related structures). To some extent, these divisions are artificial; every field overlaps with other genetic fields, and all have implications for the other biological sciences
Genetics has been applied to the diagnosis, prevention, and treatment of hereditary diseases; to the breeding of plants and animals; and to the development of industrial processes that utilize microorganisms.