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Molecular biology

a science that sets as its task the knowledge of the nature of life phenomena by studying biological objects and systems at a level approaching the molecular level, and in some cases reaching this limit. The ultimate goal in this case is to clarify how and to what extent the characteristic manifestations of life, such as heredity, reproduction of one's own kind, protein biosynthesis, excitability, growth and development, storage and transmission of information, energy transformations, mobility, etc. , are due to the structure, properties and interaction of molecules of biologically important substances, primarily the two main classes of high molecular weight biopolymers (See Biopolymers) - proteins and nucleic acids. A distinctive feature of M. b. - the study of the phenomena of life on inanimate objects or those that are characterized by the most primitive manifestations of life. These are biological formations from the cellular level and below: subcellular organelles, such as isolated cell nuclei, mitochondria, ribosomes, chromosomes, cell membranes; further - systems that stand on the border of animate and inanimate nature - viruses, including bacteriophages, and ending with molecules critical components living matter - nucleic acids (See Nucleic acids) and proteins (See Proteins).

M. b. - a new field of natural science, closely related to long-established areas of research, which are covered by biochemistry (See Biochemistry), biophysics (See Biophysics) and bioorganic chemistry (See Bioorganic Chemistry). The distinction here is possible only on the basis of taking into account the methods used and the fundamental nature of the approaches used.

The foundation on which M. developed. was laid by such sciences as genetics, biochemistry, physiology of elementary processes, etc. According to the origins of its development, M. b. inextricably linked with molecular genetics (See Molecular Genetics) , which continues to make up an important part of M. banking, although it has already formed to a large extent into an independent discipline. M.'s isolation. from biochemistry is dictated by the following considerations. The tasks of biochemistry are mainly limited to ascertaining the participation of certain chemical substances in certain biological functions and processes and elucidating the nature of their transformations; the leading role belongs to information about the reactivity and about the main features of the chemical structure, expressed by the usual chemical formula. Thus, in essence, attention is focused on transformations affecting the main valent chemical bonds. Meanwhile, as was emphasized by L. Pauling , in biological systems and manifestations of vital activity, the main importance should be given not to principal-valent bonds acting within the same molecule, but to various types of bonds that determine intermolecular interactions (electrostatic, van der Waals, hydrogen bonds, etc.).

The end result of a biochemical study can be represented in the form of a system of chemical equations, usually completely exhausted by their representation on a plane, that is, in two dimensions. A distinctive feature of M. b. is its three-dimensionality. The essence of M. b. M. Perutz sees it in interpreting biological functions in terms of molecular structure. We can say that if before, when studying biological objects, it was necessary to answer the question “what”, that is, what substances are present, and the question “where” - in which tissues and organs, then M. b. makes it his task to get answers to the question “how”, having learned the essence of the role and participation of the entire structure of the molecule, and to the questions “why” and “what for”, having found out, on the one hand, the connections between the properties of the molecule (again, primarily proteins and nucleic acids) and the functions it performs and, on the other hand, the role of such individual functions in the overall complex of manifestations of vital activity.

The mutual arrangement of atoms and their groupings in the general structure of the macromolecule, their spatial relationships acquire a decisive role. This applies to both individual, individual components, and the overall configuration of the molecule as a whole. It is as a result of the emergence of a strictly determined volumetric structure that biopolymer molecules acquire those properties, due to which they are able to serve as the material basis of biological functions. This principle of approach to the study of the living is the most characteristic, typical feature of M. b.

Historical reference. The great importance of studying biological problems at the molecular level was foreseen by I. P. Pavlov , who spoke about the last step in the science of life - the physiology of the living molecule. The very term "M. b." was first used in English. scientists W. Astbury in application to research related to the elucidation of the relationship between the molecular structure and physical and biological properties fibrillar (fibrous) proteins such as collagen, blood fibrin, or contractile muscle proteins. Widely use the term "M. b." steel since the early 1950s. 20th century

M.'s emergence. as a mature science, it is customary to refer to 1953, when J. Watson and F. Crick in Cambridge (Great Britain) discovered the three-dimensional structure of deoxyribonucleic acid (DNA). This made it possible to speak about how the details of this structure determine the biological functions of DNA as a material carrier of hereditary information. In principle, this role of DNA became known somewhat earlier (1944) as a result of the work of the American geneticist O. T. Avery and coworkers (see Molecular Genetics), but it was not known to what extent given function depends on the molecular structure of DNA. This became possible only after the laboratories of W. L. Bragg, J. Bernal, and others developed new principles of X-ray diffraction analysis, which ensured the use of this method for a detailed knowledge of the spatial structure of protein macromolecules and nucleic acids.

Levels of molecular organization. In 1957, J. Kendrew established the three-dimensional structure of Myoglobin a , and in subsequent years, this was done by M. Perutz in relation to Hemoglobin a. Ideas about different levels of spatial organization of macromolecules were formulated. The primary structure is a sequence of individual units (monomers) in the chain of the resulting polymer molecule. For proteins, the monomers are amino acids. , for nucleic acids - Nucleotides. A linear, filamentous molecule of a biopolymer, as a result of the occurrence of hydrogen bonds, has the ability to fit in space in a certain way, for example, in the case of proteins, as shown by L. Pauling, it can take the form of a spiral. This is referred to as a secondary structure. Tertiary structure is said to be when a molecule that has a secondary structure further folds in one way or another, filling three-dimensional space. Finally, molecules that have a three-dimensional structure can enter into interaction, regularly located in space relative to each other and forming what is designated as a quaternary structure; its individual components are commonly referred to as subunits.

Most good example How the molecular three-dimensional structure determines the biological functions of the molecule is DNA. It has the structure of a double helix: two threads running in a mutually opposite direction (antiparallel) are twisted one around the other, forming a double helix with a mutually complementary arrangement of bases, i.e. so that against a certain base of one chain there is always such a foundation, which the best way provides the formation of hydrogen bonds: adepine (A) forms a pair with thymine (T), guanine (G) - with cytosine (C). This structure creates optimal conditions for the most important biological functions of DNA: the quantitative multiplication of hereditary information in the process of cell division while maintaining the qualitative invariance of this flow of genetic information. When a cell divides, the strands of the DNA double helix, which serves as a template, or template, unwind and on each of them, under the action of enzymes, a complementary new strand is synthesized. As a result of this, two completely identical daughter molecules are obtained from one parent DNA molecule (see Cell, Mitosis).

Similarly, in the case of hemoglobin, it turned out that its biological function - the ability to reversibly attach oxygen in the lungs and then give it to tissues - is closely related to the features of the three-dimensional structure of hemoglobin and its changes in the process of implementing its physiological role. When binding and dissociating O 2, spatial changes in the conformation of the hemoglobin molecule occur, leading to a change in the affinity of the iron atoms contained in it for oxygen. Changes in the size of the hemoglobin molecule, resembling changes in volume chest when breathing, allowed to call hemoglobin "molecular lungs".

One of the most important features of living objects is their ability to finely regulate all manifestations of vital activity. M.'s major contribution. scientific discoveries should be considered the discovery of a new, previously unknown regulatory mechanism, referred to as the allosteric effect. It lies in the ability of substances of low molecular weight - the so-called. ligands - to modify the specific biological functions of macromolecules, primarily catalytically acting proteins - enzymes, hemoglobin, receptor proteins involved in the construction of biological membranes (See Biological membranes), in synaptic transmission (see Synapses), etc.

Three biotic streams. In the light of M.'s ideas. the totality of the phenomena of life can be considered as the result of a combination of three flows: the flow of matter, which finds its expression in the phenomena of metabolism, i.e., assimilation and dissimilation; the flow of energy, which is the driving force for all manifestations of life; and the flow of information, penetrating not only the whole variety of processes of development and existence of each organism, but also a continuous series of successive generations. It is the idea of ​​the flow of information, introduced into the doctrine of the living world by the development of biomaterials, that leaves its own specific, unique imprint on it.

The most important achievements of molecular biology. Swiftness, scope and depth of M.'s influence. progress in understanding the fundamental problems of the study of living nature is rightly compared, for example, with the influence of quantum theory on the development of atomic physics. Two intrinsically related conditions determined this revolutionary impact. On the one hand, a decisive role was played by the discovery of the possibility of studying the most important manifestations of vital activity under the simplest conditions, approaching the type of chemical and physical experiments. On the other hand, as a consequence of this circumstance, there was a rapid involvement of a significant number of representatives of the exact sciences - physicists, chemists, crystallographers, and then mathematicians - in the development of biological problems. In their totality, these circumstances determined the unusually rapid pace of development of M. b., the number and significance of its successes, achieved in just two decades. Here is a far from complete list of these achievements: disclosure of the structure and mechanism of the biological function of DNA, all types of RNA and ribosomes (See Ribosomes) , disclosure of the genetic code (See genetic code) ; discovery of reverse transcription (See transcription) , i.e. DNA synthesis on an RNA template; study of the mechanisms of functioning of respiratory pigments; discovery of a three-dimensional structure and its functional role in the action of enzymes (See Enzymes) , the principle of matrix synthesis and mechanisms of protein biosynthesis; disclosure of the structure of viruses (See Viruses) and the mechanisms of their replication, the primary and, in part, the spatial structure of antibodies; isolation of individual genes , chemical and then biological (enzymatic) gene synthesis, including human, outside the cell (in vitro); transfer of genes from one organism to another, including into human cells; the rapidly progressing deciphering of the chemical structure of an increasing number of individual proteins, mainly enzymes, as well as nucleic acids; discovery of the phenomena of "self-assembly" of some biological objects of ever-increasing complexity, starting from nucleic acid molecules and moving on to multicomponent enzymes, viruses, ribosomes, etc.; elucidation of allosteric and other basic principles of regulation of biological functions and processes.

Reductionism and integration. M. b. is the final stage of that direction in the study of living objects, which is designated as "reductionism", i.e., the desire to reduce complex life functions to phenomena occurring at the molecular level and therefore accessible to study by the methods of physics and chemistry. Achieved M. b. successes testify to the effectiveness of this approach. At the same time, it must be taken into account that in natural conditions in a cell, tissue, organ, and the whole organism, we are dealing with systems of increasing complexity. Such systems are formed from lower-level components through their regular integration into wholes, acquiring a structural and functional organization and possessing new properties. Therefore, as the knowledge of patterns available for disclosure at the molecular and adjacent levels is detailed, before M. b. the task of understanding the mechanisms of integration as a line of further development in the study of the phenomena of life arises. The starting point here is the study of the forces of intermolecular interactions - hydrogen bonds, van der Waals, electrostatic forces, etc. By their combination and spatial arrangement, they form what can be designated as "integrative information". It should be considered as one of the main parts of the already mentioned flow of information. In M.'s area. examples of integration can be the phenomena of self-assembly of complex formations from a mixture of their constituent parts. This includes, for example, the formation of multicomponent proteins from their subunits, the formation of viruses from their constituent parts - proteins and nucleic acids, the restoration of the original structure of ribosomes after the separation of their protein and nucleic components, etc. The study of these phenomena is directly related to the knowledge of the main phenomena " recognition” of biopolymer molecules. The point is to find out what combinations of amino acids - in protein molecules or nucleotides - in nucleic acids interact with each other during the processes of association of individual molecules with the formation of complexes of a strictly specific, predetermined composition and structure. These include the processes of formation of complex proteins from their subunits; further, selective interaction between nucleic acid molecules, for example, transport and matrix (in this case, the discovery of the genetic code has significantly expanded our information); finally, this is the formation of many types of structures (for example, ribosomes, viruses, chromosomes), in which both proteins and nucleic acids participate. The disclosure of the relevant patterns, the knowledge of the "language" underlying these interactions, is one of the critical areas M. b., still awaiting its development. This area is considered as belonging to the number of fundamental problems for the entire biosphere.

Problems of molecular biology. Along with the specified important tasks M. would. (knowledge of the laws of "recognition", self-assembly and integration) the actual direction of scientific search for the near future is the development of methods that allow deciphering the structure, and then the three-dimensional, spatial organization of high-molecular nucleic acids. This has now been achieved with respect to the general plan of the three-dimensional structure of DNA (double helix), but without exact knowledge of its primary structure. Rapid progress in the development of analytical methods allows us to confidently expect the achievement of these goals over the coming years. Here, of course, the main contributions come from representatives of related sciences, primarily physics and chemistry. All the most important methods, the use of which ensured the emergence and success of M. b., were proposed and developed by physicists (ultracentrifugation, X-ray diffraction analysis, electron microscopy, nuclear magnetic resonance, etc.). Almost all new physical experimental approaches (for example, the use of computers, synchrotron, or bremsstrahlung, radiation, laser technology, and others) open up new possibilities for an in-depth study of the problems of M. b. Among the most important tasks of a practical nature, the answer to which is expected from M. b., in the first place is the problem of the molecular basis of malignant growth, then - ways to prevent, and perhaps overcome hereditary diseases - "molecular diseases" (See Molecular diseases ). Of great importance will be the elucidation of the molecular basis of biological catalysis, ie, the action of enzymes. Among the most important modern trends M. b. should include the desire to decipher the molecular mechanisms of action of hormones (See Hormones) , toxic and medicinal substances, as well as to find out the details of the molecular structure and functioning of such cellular structures as biological membranes involved in the regulation of the processes of penetration and transport of substances. More distant goals M. b. - knowledge of the nature of nervous processes, memory mechanisms (See Memory), etc. One of the important emerging sections of M. b. - so-called. genetic engineering, which sets as its task the purposeful operation of the genetic apparatus (Genome) of living organisms, starting with microbes and lower (single-celled) and ending with humans (in the latter case, primarily for the purpose of radical treatment of hereditary diseases (See. Hereditary diseases) and the correction of genetic defects ). More extensive interventions in the human genetic basis can only be discussed in a more or less distant future, since in this case serious obstacles, both technical and fundamental, arise. Concerning microbes, plants, and it is possible, and page - x. For animals, such prospects are very encouraging (for example, obtaining varieties of cultivated plants that have an apparatus for fixing nitrogen from the air and do not need fertilizers). They are based on the successes already achieved: the isolation and synthesis of genes, the transfer of genes from one organism to another, the use of mass cell cultures as producers of economic or medically important substances.

Organization of research in molecular biology. M.'s rapid development. led to the emergence of a large number of specialized research centers. Their number is growing rapidly. The largest: in the UK - the Laboratory of Molecular Biology in Cambridge, the Royal Institute in London; in France - institutes of molecular biology in Paris, Marseille, Strasbourg, the Pasteur Institute; in the USA - departments M. b. at universities and institutes in Boston (Harvard University, Massachusetts Institute of Technology), San Francisco (Berkeley), Los Angeles (California Institute of Technology), New York (Rockefeller University), health institutes in Bethesda, etc.; in Germany - Max Planck institutes, universities in Göttingen and Munich; in Sweden, the Karolinska Institute in Stockholm; in the GDR - the Central Institute for Molecular Biology in Berlin, institutes in Jena and Halle; in Hungary - Biological Center in Szeged. In the USSR the first specialized institute M. would be. was created in Moscow in 1957 in the system of the Academy of Sciences of the USSR (see. ); then the following were formed: the Institute of Bioorganic Chemistry of the Academy of Sciences of the USSR in Moscow, the Institute of Protein in Pushchino, the Biological Department at the Institute of Atomic Energy (Moscow), and the departments of M. b. at the institutes of the Siberian Branch of the Academy of Sciences in Novosibirsk, the Interdepartmental Laboratory of Bioorganic Chemistry of the Moscow State University, the Sector (later the Institute) of Molecular Biology and Genetics of the Academy of Sciences of the Ukrainian SSR in Kyiv; significant work on M. b. is conducted at the Institute of Macromolecular Compounds in Leningrad, in a number of departments and laboratories of the Academy of Sciences of the USSR and other departments.

Along with individual research centers, organizations of a wider scale arose. In Western Europe, the European Organization for M. arose. (EMBO), in which more than 10 countries participate. In the USSR, in 1966, at the Institute of Molecular Biology, a Scientific Council on M. B. was established, which is the coordinating and organizing center in this field of knowledge. He published an extensive series of monographs on the most important sections of M. B., “winter schools” on M. B. are regularly organized, conferences and symposiums are held on topical issues M. b. In the future, scientific advice on M. would. were created at the Academy of Medical Sciences of the USSR and many republican Academies of Sciences. The journal Molecular Biology has been published since 1966 (6 issues per year).

For rather short term in the USSR the considerable group of researchers in the field of M. has grown; these are scientists of the older generation who have partially switched their interests from other fields; for the most part, they are numerous young researchers. From among the leading scientists who took an active part in the formation and development of M. b. in the USSR, one can name such as A. A. Baev, A. N. Belozersky, A. E. Braunshtein, Yu. A. Ovchinnikov, A. S. Spirin, M. M. Shemyakin, V. A. Engelgardt. M.'s new achievements. and molecular genetics will be promoted by the resolution of the Central Committee of the CPSU and the Council of Ministers of the USSR (May 1974) "On measures to accelerate the development of molecular biology and molecular genetics and the use of their achievements in the national economy."

Lit.: Wagner R., Mitchell G., Genetics and metabolism, trans. from English, M., 1958; Szent-Gyorgy and A., Bioenergetics, trans. from English, M., 1960; Anfinsen K., Molecular basis of evolution, trans. from English, M., 1962; Stanley W., Valens E., Viruses and the nature of life, trans. from English, M., 1963; Molecular genetics, trans. With. English, part 1, M., 1964; Volkenstein M.V., Molecules and life. Introduction to molecular biophysics, M., 1965; Gaurowitz F., Chemistry and functions of proteins, trans. from English, M., 1965; Bresler S. E., Introduction to molecular biology, 3rd ed., M. - L., 1973; Ingram V., Biosynthesis of macromolecules, trans. from English, M., 1966; Engelhardt V. A., Molecular biology, in the book: Development of biology in the USSR, M., 1967; Introduction to molecular biology, trans. from English, M., 1967; Watson, J., Molecular Biology of the Gene, trans. from English, M., 1967; Finean J., Biological ultrastructures, trans. from English, M., 1970; Bendoll, J., Muscles, Molecules, and Movement, trans. from English, M., 1970; Ichas M., Biological code, trans. from English, M., 1971; Molecular biology of viruses, M., 1971; Molecular bases of protein biosynthesis, M., 1971; Bernhard S., Structure and function of enzymes, trans. from English, M., 1971; Spirin A. S., Gavrilova L. P., Ribosome, 2nd ed., M., 1971; Frenkel-Konrat H., Chemistry and biology of viruses, trans. from English, M., 1972; Smith C., Hanewalt F., Molecular Photobiology. Processes of inactivation and recovery, trans. from English, M., 1972; Harris G., Fundamentals of human biochemical genetics, trans. from English, M., 1973.

V. A. Engelhardt.

Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .

Comic book for the contest "bio/mol/text": Today, the molecular biologist Test Tube will guide you through the world of amazing science - molecular biology! We will start with a historical excursion through the stages of its development, we will describe the main discoveries and experiments since 1933. And we will also clearly describe the main methods of molecular biology, which made it possible to manipulate genes, change and isolate them. The emergence of these methods served as a strong impetus to the development of molecular biology. And let's also remember the role of biotechnology and touch on one of the most popular topics in this area - genome editing using CRISPR/Cas systems.

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1. Introduction. Essence of molecular biology

It studies the basics of the vital activity of organisms at the level of macromolecules. The goal of molecular biology is to establish the role and mechanisms of functioning of these macromolecules on the basis of knowledge about their structures and properties.

Historically, molecular biology was formed during the development of areas of biochemistry that study nucleic acids and proteins. While biochemistry is the study of metabolism, chemical composition living cells, organisms and the chemical processes carried out in them, molecular biology focuses on the study of the mechanisms of transmission, reproduction and storage of genetic information.

And the object of study of molecular biology is the nucleic acids themselves - deoxyribonucleic (DNA), ribonucleic (RNA) - and proteins, as well as their macromolecular complexes - chromosomes, ribosomes, multienzyme systems that provide the biosynthesis of proteins and nucleic acids. Molecular biology also borders on the objects of study and partially coincides with molecular genetics, virology, biochemistry and a number of other related biological sciences.

2. Historical excursion through the stages of development of molecular biology

As a separate area of ​​biochemistry, molecular biology began to develop in the 30s of the last century. Even then, it became necessary to understand the phenomenon of life at the molecular level in order to study the processes of transmission and storage of genetic information. Just at that time, the task of molecular biology was established in the study of the properties, structure and interaction of proteins and nucleic acids.

The term "molecular biology" was first used in 1933 year William Astbury during the study of fibrillar proteins (collagen, blood fibrin, contractile muscle proteins). Astbury studied the relationship between the molecular structure and the biological, physical characteristics of these proteins. At the beginning of the emergence of molecular biology, RNA was considered to be a component only of plants and fungi, and DNA - only animals. And in 1935 The discovery of pea DNA by Andrei Belozersky led to the establishment of the fact that DNA is contained in every living cell.

IN 1940 A colossal achievement was the establishment by George Beadle and Edward Tatham of a causal relationship between genes and proteins. The scientists' hypothesis "One gene - one enzyme" formed the basis for the concept that the specific structure of a protein is regulated by genes. It is believed that genetic information is encoded by a special sequence of nucleotides in DNA that regulates the primary structure of proteins. Later it was proved that many proteins have a quaternary structure. Various peptide chains take part in the formation of such structures. Based on this, the provision on the relationship between a gene and an enzyme has been somewhat transformed, and now it sounds like "One gene - one polypeptide."

IN 1944 In 1999, the American biologist Oswald Avery and his colleagues (Colin McLeod and McLean McCarthy) proved that the substance that causes the transformation of bacteria is DNA, not proteins. The experiment served as proof of the role of DNA in the transmission of hereditary information, crossing out outdated knowledge about the protein nature of genes.

In the early 1950s, Frederick Sanger showed that a protein chain is a unique sequence of amino acid residues. IN 1951 And 1952 years, the scientist determined the complete sequence of two polypeptide chains - bovine insulin IN(30 amino acid residues) and A(21 amino acid residues), respectively.

Around the same time, in 1951–1953 Erwin Chargaff formulated the rules for the ratio of nitrogenous bases in DNA. According to the rule, regardless of the species differences of living organisms in their DNA, the amount of adenine (A) is equal to the amount of thymine (T), and the amount of guanine (G) is equal to the amount of cytosine (C).

IN 1953 proved the genetic role of DNA. James Watson and Francis Crick, based on the X-ray of DNA obtained by Rosalind Franklin and Maurice Wilkins, established the spatial structure of DNA and put forward a later confirmed assumption about the mechanism of its replication (doubling), which underlies heredity.

1958 year - the formation of the central dogma of molecular biology by Francis Crick: the transfer of genetic information goes in the direction of DNA → RNA → protein.

The essence of the dogma is that in cells there is a certain directed flow of information from DNA, which, in turn, is the original genetic text, consisting of four letters: A, T, G and C. It is written in the DNA double helix in the form sequences of these letters - nucleotides.

This text is being transcribed. And the process is called transcription. During this process, RNA is synthesized, which is identical to the genetic text, but with a difference: in RNA, instead of T, there is U (uracil).

This RNA is called messenger RNA (mRNA), or matrix (mRNA). Broadcast mRNA is carried out using the genetic code in the form of triplet sequences of nucleotides. During this process, the text of DNA and RNA nucleic acids is translated from a four-letter text into a twenty-letter text of amino acids.

There are only twenty natural amino acids, and there are four letters in the text of nucleic acids. Because of this, there is a translation from the four-letter alphabet to the twenty-letter alphabet through the genetic code, in which each three nucleotides corresponds to an amino acid. So you can make whole 64 three-letter combinations from four letters, moreover, there are 20 amino acids. From this it follows that the genetic code must necessarily have the property of degeneracy. However, at that time the genetic code was not known, besides, it had not even begun to be deciphered, but Crick had already formulated his central dogma.

Nevertheless, there was a certainty that the code must exist. By that time, it had been proved that this code had a triplet character. This means that specifically three letters in nucleic acids ( codons) correspond to any amino acid. There are 64 of these codons, they code for 20 amino acids. This means that each amino acid corresponds to several codons at once.

Thus, we can conclude that the central dogma is a postulate that says that a directed flow of information occurs in the cell: DNA → RNA → protein. Crick emphasized the main content of the central dogma: the reverse flow of information cannot occur, the protein is not capable of changing genetic information.

This is the main meaning of the central dogma: a protein is not able to change and transform information into DNA (or RNA), the flow always goes only in one direction.

Some time after this, a new enzyme was discovered, which was not known at the time of the formulation of the central dogma, - reverse transcriptase that synthesizes DNA from RNA. The enzyme was discovered in viruses, in which the genetic information is encoded in RNA, not DNA. Such viruses are called retroviruses. They have a viral capsule with RNA enclosed in it and a special enzyme. The enzyme is a reverse transcriptase that synthesizes DNA according to the template of this viral RNA, and this DNA then serves as the genetic material for the further development of the virus in the cell.

Of course, this discovery caused great shock and much controversy among molecular biologists, since it was believed that, based on central dogma, this could not be. However, Crick immediately explained that he never said it was impossible. He only said that there can never be a flow of information from protein to nucleic acids, and already inside nucleic acids any kind of processes are quite possible: the synthesis of DNA on DNA, DNA on RNA, RNA on DNA and RNA on RNA.

After the formulation of the central dogma, a number of questions still remained: how does the alphabet of four nucleotides that make up DNA (or RNA) encode the 20-letter alphabet of amino acids that make up proteins? What is the essence of the genetic code?

The first ideas about the existence of the genetic code were formulated by Alexander Downes ( 1952 d.) and Georgy Gamov ( 1954 G.). Scientists have shown that the sequence of nucleotides must include at least three links. Later it was proved that such a sequence consists of three nucleotides, called codon (triplet). However, the question of which nucleotides are responsible for incorporating which amino acid into a protein molecule remained open until 1961.

And in 1961 Marshall Nirenberg, along with Heinrich Mattei, used the system to broadcast in vitro. An oligonucleotide was used as a template. It contained only uracil residues, and the peptide synthesized from it included only the amino acid phenylalanine. Thus, the meaning of the codon was first established: the codon UUU codes for phenylalanine. Later, Har Qur'an found that the nucleotide sequence UCUCUCUCUCUC encodes a set of amino acids serine-leucine-serine-leucine. By and large, thanks to the works of Nirenberg and the Koran, to 1965 year, the genetic code was completely unraveled. It turned out that each triplet encodes a specific amino acid. And the order of the codons determines the order of the amino acids in the protein.

The main principles of the functioning of proteins and nucleic acids were formulated by the beginning of the 70s. It was found that the synthesis of proteins and nucleic acids is carried out according to the matrix mechanism. The template molecule carries encoded information about the sequence of amino acids or nucleotides. During replication or transcription, the template is DNA, and during translation and reverse transcription, it is mRNA.

Thus, the prerequisites for the formation of areas of molecular biology, including genetic engineering, were created. And in 1972, Paul Berg and colleagues developed the technology of molecular cloning. Scientists have obtained the first recombinant DNA in vitro. These outstanding discoveries formed the basis of a new direction in molecular biology, and 1972 the year has since been considered the birth date of genetic engineering.

3. Methods of molecular biology

Enormous advances in the study of nucleic acids, the structure of DNA and protein biosynthesis have led to the creation of a number of methods of great importance in medicine, agriculture and science in general.

After studying the genetic code and the basic principles of storage, transmission and implementation of hereditary information, special methods became necessary for the further development of molecular biology. These methods would allow genes to be manipulated, altered and isolated.

The emergence of such methods occurred in the 1970s and 1980s. This gave a huge impetus to the development of molecular biology. First of all, these methods are directly related to the production of genes and their introduction into the cells of other organisms, as well as the possibility of determining the nucleotide sequence in genes.

3.1. DNA electrophoresis

DNA electrophoresis is the basic method of working with DNA. DNA electrophoresis is used along with almost all other methods to isolate the desired molecules and further analyze the results. The gel electrophoresis method itself is used to separate DNA fragments by length.

Before or after electrophoresis, the gel is treated with dyes that can bind to DNA. The dyes fluoresce in ultraviolet light, resulting in a pattern of bands in the gel. To determine the length of DNA fragments, they can be compared with markers- sets of fragments of standard lengths, which are applied to the same gel.

Fluorescent proteins

When studying eukaryotic organisms, it is convenient to use fluorescent proteins as marker genes. The gene for the first green fluorescent protein ( green fluorescent protein, GFP) isolated from jellyfish Aqeuorea victoria and then introduced into various organisms. After that, genes for fluorescent proteins of other colors were isolated: blue, yellow, red. To obtain proteins with properties of interest, such genes have been artificially modified.

In general, the most important tools for working with the DNA molecule are enzymes that carry out a number of DNA transformations in cells: DNA polymerase, DNA ligases And restrictases (restriction endonucleases).

transgenesis

transgenesis It is called the transfer of genes from one organism to another. Such organisms are called transgenic.

Recombinant protein preparations are just obtained by transferring genes into microorganism cells. Most of these proteins are interferons, insulin, some protein hormones, as well as proteins for the production of a number of vaccines.

In other cases, cell cultures of eukaryotes or transgenic animals, mostly livestock, are used, which secrete the necessary proteins into milk. In this way, antibodies, blood clotting factors and other proteins are obtained. The transgenesis method is used to obtain crops resistant to pests and herbicides, and wastewater is treated with the help of transgenic microorganisms.

In addition to all of the above, transgenic technologies are indispensable in scientific research, because the development of biology is faster with the use of gene modification and transfer methods.

Restrictases

The sequences recognized by restriction enzymes are symmetrical, so any kind of breaks can occur either in the middle of such a sequence, or with a shift in one or both strands of the DNA molecule.

When splitting any DNA with a restriction enzyme, the sequences at the ends of the fragments will be the same. They will be able to connect again because they have complementary sites.

You can get a single molecule by stitching these sequences using DNA ligases. Due to this, it is possible to combine fragments of two different DNA and obtain recombinant DNA.

3.2. PCR

The method is based on the ability of DNA polymerases to complete the second strand of DNA along the complementary strand in the same way as in the process of DNA replication in a cell.

3.3. DNA sequencing

The rapid development of the sequencing method makes it possible to effectively determine the characteristics of the organism under study at the level of its genome. The main advantage of such genomic and post-genomic technologies is the increase in research and study opportunities. genetic nature human diseases, in order to pre-take necessary measures and avoid illness.

Through large-scale research, it is possible to obtain the necessary data on the various genetic characteristics of different groups of people, thereby developing the methods of medicine. Because of this, the identification of a genetic predisposition to various diseases is very popular today.

Similar methods are widely applicable practically all over the world, including in Russia. Due to scientific progress, such methods are being introduced into medical research and medical practice generally.

4. Biotechnology

Biotechnology- a discipline that studies the possibilities of using living organisms or their systems to solve technological problems, as well as creating living organisms with desired properties through genetic engineering. Biotechnology applies the methods of chemistry, microbiology, biochemistry and, of course, molecular biology.

The main directions of development of biotechnology (the principles of biotechnological processes are being introduced into the production of all industries):

1. Creation and production of new types of food and animal feed.
2. Obtaining and studying new strains of microorganisms.
3. Breeding of new varieties of plants, as well as the creation of means for protecting plants from diseases and pests.
4. Application of biotechnology methods for the needs of ecology. Such biotechnology methods are used for waste recycling, wastewater treatment, exhaust air and soil sanitation.
5. Production of vitamins, hormones, enzymes, serums for the needs of medicine. Biotechnologists are developing improved medications previously considered incurable.

A major achievement in biotechnology is genetic engineering.

Genetic Engineering- a set of technologies and methods for obtaining recombinant RNA and DNA molecules, isolating individual genes from cells, manipulating genes and introducing them into other organisms (bacteria, yeast, mammals). Such organisms are able to produce final products with the desired, modified properties.

Genetic engineering methods are aimed at constructing new, previously non-existing combinations of genes in nature.

Speaking about the achievements of genetic engineering, it is impossible not to touch on the topic of cloning. Cloning is one of the methods of biotechnology used to obtain identical offspring of different organisms through asexual reproduction.

In other words, cloning can be thought of as the process of creating genetically identical copies of an organism or cell. And cloned organisms are similar or completely identical not only in external features, but also in genetic content.

The notorious sheep Dolly in 1966 became the first cloned mammal. It was obtained by transplanting the nucleus of a somatic cell into the cytoplasm of the egg. Dolly was a genetic copy of the nucleus donor sheep. Under natural conditions, an individual is formed from one fertilized egg, having received half of the genetic material from two parents. However, during cloning, the genetic material was taken from the cell of one individual. First, the nucleus, which contains the DNA itself, was removed from the zygote. Then they removed the nucleus from the adult sheep cell and implanted it in that zygote without the nucleus, and then it was transplanted into the uterus of an adult and allowed to grow and develop.

However, not all cloning attempts have been successful. In parallel with Dolly's cloning, a DNA replacement experiment was carried out on 273 other eggs. But only in one case could a living adult animal fully develop and grow. After Dolly, scientists tried to clone other types of mammals.

One of the types of genetic engineering is genome editing.

The CRISPR/Cas tool is based on an element of the immune defense system of bacteria, which scientists have adapted to introduce any changes in the DNA of animals or plants.

CRISPR/Cas is one of the biotechnological methods for manipulating individual genes in cells. There are many applications for this technology. CRISPR/Cas allows researchers to figure out the function of different genes. To do this, you just need to cut out the gene under study from the DNA and study which functions of the body were affected.

Some practical applications of the system:

1. Agriculture. Through CRISPR/Cas systems, crops can be improved. Namely, to make them more tasty and nutritious, as well as resistant to heat. It is possible to endow plants with other properties: for example, cut out an allergen gene from nuts (peanuts or hazelnuts).
2. Medicine, hereditary diseases. Scientists have a goal to use CRISPR/Cas to remove mutations from the human genome that can cause diseases, such as sickle cell anemia, etc. In theory, CRISPR/Cas can stop the development of HIV.
3. Gene drive. CRISPR/Cas can change not only the genome of an individual animal or plant, but also the gene pool of a species. This concept is known as "gene drive". Every living organism passes on half of its genes to its offspring. But using CRISPR/Cas can increase the chance of gene transfer by up to 100%. This is important in order for the desired trait to spread faster throughout the population.

Swiss scientists have significantly improved and modernized the CRISPR/Cas genome editing method, thereby expanding its capabilities. However, scientists could only modify one gene at a time using the CRISPR/Cas system. But now researchers at ETH Zurich have developed a method that can simultaneously modify 25 genes in a cell.

For the latest technique, experts used the Cas12a enzyme. Geneticists have successfully cloned monkeys for the first time in history. "Popular Mechanics";

Nikolenko S. (2012). Genomics: Problem Statement and Sequencing Methods. "Post-science".

31.2

For friends!

Reference

Molecular biology grew out of biochemistry in April 1953. Its appearance is associated with the names of James Watson and Francis Crick, who discovered the structure of the DNA molecule. The discovery was made possible through the study of genetics, bacteria and the biochemistry of viruses. The profession of a molecular biologist is not widespread, but today its role in modern society is very large. A large number of diseases, including those manifested at the genetic level, require scientists to find solutions to this problem.

Description of activity

Viruses and bacteria are constantly mutating, which means that medicines no longer help a person and diseases become intractable. The task of molecular biology is to get ahead of this process and develop a new cure for diseases. Scientists work according to a well-established scheme: blocking the cause of the disease, eliminating the mechanisms of heredity and thereby alleviating the patient's condition. There are a number of centers, clinics and hospitals around the world where molecular biologists are developing new treatments to help patients.

Job responsibilities

The responsibilities of a molecular biologist include the study of processes inside the cell (for example, changes in DNA during the development of tumors). Also, experts study the features of DNA, their effect on the whole organism and a single cell. Such studies are carried out, for example, on the basis of PCR (polymerase chain reaction), which allows you to analyze the body for infections, hereditary diseases and determine biological relationship.

Features of career growth

The profession of a molecular biologist is quite promising in its field and already today claims to be the first in the ranking of medical professions of the future. By the way, a molecular biologist does not have to stay in this field all the time. If there is a desire to change occupation, he can retrain as a sales manager for laboratory equipment, start developing instruments for various studies, or open his own business.

1. Introduction.

Subject, tasks and methods of molecular biology and genetics. Significance of "classical" genetics and genetics of microorganisms in the development of molecular biology and genetic engineering. The concept of a gene in "classical" and molecular genetics, its evolution. Contribution of genetic engineering methodology to the development of molecular genetics. Applied value of genetic engineering for biotechnology.

2. Molecular bases of heredity.

The concept of a cell, its macromolecular composition. The nature of the genetic material. History of evidence for the genetic function of DNA.

2.1. Various types of nucleic acids. Biological functions of nucleic acids. Chemical structure, spatial structure and physical properties nucleic acids. Structural features of the genetic material of pro- and eukaryotes. Complementary Watson-Crick base pairs. Genetic code. The history of deciphering the genetic code. The main properties of the code: triplet, code without commas, degeneracy. Features of the code dictionary, families of codons, semantic and "meaningless" codons. Circular DNA molecules and the concept of DNA supercoiling. Topoisomers of DNA and their types. Mechanisms of action of topoisomerases. Bacterial DNA gyrase.

2.2. DNA transcription. Prokaryotic RNA polymerase, its subunit and three-dimensional structures. Variety of sigma factors. Prokaryotic gene promoter, its structural elements. Stages of the transcription cycle. Initiation, formation of an “open complex”, elongation and termination of transcription. transcription attenuation. Regulation of tryptophan operon expression. "Riboswitches". Transcription termination mechanisms. Negative and positive regulation of transcription. lactose operon. Transcriptional regulation in lambda phage development. Principles of DNA recognition by regulatory proteins (CAP protein and lambda phage repressor). Features of transcription in eukaryotes. RNA processing in eukaryotes. Capping, splicing and polyadenylation of transcripts. splicing mechanisms. The role of small nuclear RNA and protein factors. Alternative splicing, examples.

2.3. Broadcast, its stages, the function of ribosomes. Location of ribosomes in the cell. Prokaryotic and eukaryotic types of ribosomes; 70S and 80S ribosomes. Morphology of ribosomes. Division into subparticles (subunits). Codon-dependent binding of aminoacyl-tRNA in the elongation cycle. Codon-anticodon interaction. Participation of the elongation factor EF1 (EF-Tu) in the binding of aminoacyl-tRNA to the ribosome. Elongation factor EF1B (EF-Ts), its function, sequence of reactions with its participation. Antibiotics affecting the stage of codon-dependent binding of aminoacyl-tRNA to the ribosome. Aminoglycoside antibiotics (streptomycin, neomycin, kanamycin, gentamicin, etc.), their mechanism of action. Tetracyclines as inhibitors of aminoacyl-tRNA binding to the ribosome. Broadcast initiation. The main stages of the initiation process. Translation initiation in prokaryotes: initiation factors, initiator codons, RNA 3¢-end of the small ribosomal subunit, and the Shine-Dalgarno sequence in mRNA. Translation initiation in eukaryotes: initiation factors, initiator codons, 5¢-untranslated region and cap-dependent terminal initiation. "Internal" cap-independent initiation in eukaryotes. Transpeptidation. Transpeptidation inhibitors: chloramphenicol, lincomycin, amicetin, streptogramins, anisomycin. Translocation. Involvement of elongation factor EF2 (EF-G) and GTP. Translocation inhibitors: fusidic acid, viomycin, their mechanisms of action. Translation termination. Termination codons. Protein termination factors of prokaryotes and eukaryotes; two classes of termination factors and mechanisms of their action. Regulation of translation in prokaryotes.

2.4. DNA replication and its genetic control. Polymerases involved in replication, characteristics of their enzymatic activities. DNA fidelity. The role of steric interactions between DNA base pairs during replication. E. coli polymerases I, II, and III. Polymerase III subunits. Replication fork, "leading" and "lagging" threads during replication. Fragments of the Okazaki. Complex of proteins in the replication fork. Regulation of replication initiation in E. coli. Termination of replication in bacteria. Features of the regulation of plasmid replication. Bidirectional and rolling ring replication.

2.5. Recombination, its types and models. General or homologous recombination. Double-strand breaks in DNA that initiate recombination. The role of recombination in post-replication repair of double-strand breaks. Holliday structure in the recombination model. Enzymology of general recombination in E. coli. RecBCD complex. Reca protein. The role of recombination in ensuring DNA synthesis in DNA damage interrupting replication. recombination in eukaryotes. Recombination enzymes in eukaryotes. Site-specific recombination. Differences in the molecular mechanisms of general and site-specific recombination. Classification of recombinases. Types of chromosomal rearrangements carried out during site-specific recombination. Regulatory role of site-specific recombination in bacteria. Construction of multicellular eukaryotic chromosomes using the site-specific phage recombination system.

2.6. DNA repair. Classification of types of reparation. Direct repair of thymine dimers and methylated guanine. Cutting out bases. Glycosylases. The mechanism of repair of unpaired nucleotides (mismatch repair). Selection of the DNA strand to be repaired. SOS repair. Properties of DNA polymerases involved in SOS repair in prokaryotes and eukaryotes. The concept of "adaptive mutations" in bacteria. Repair of double-strand breaks: homologous post-replicative recombination and association of non-homologous ends of the DNA molecule. The relationship between the processes of replication, recombination and reparation.

3. Mutation process.

The role of biochemical mutants in the formation of the theory of one gene - one enzyme. Mutation classification. Point mutations and chromosomal rearrangements, the mechanism of their formation. Spontaneous and induced mutagenesis. Classification of mutagens. Molecular mechanism of mutagenesis. Relationship between mutagenesis and repair. Identification and selection of mutants. Suppression: intragenic, intergenic and phenotypic.

4. Extrachromosomal genetic elements.

Plasmids, their structure and classification. Sex factor F, its structure and life cycle. The role of factor F in the mobilization of chromosome transfer. Formation of Hfr and F donors. Mechanism of conjugation. Bacteriophages, their structure and life cycle. Virulent and temperate bacteriophages. Lysogeny and transduction. General and specific transduction. Migrating genetic elements: transposons and IS sequences, their role in genetic metabolism. DNA -transposons in the genomes of prokaryotes and eukaryotes IS-sequences of bacteria, their structure IS-sequences as a component of the F-factor of bacteria, which determines the ability to transfer genetic material during conjugation Transposons of bacteria and eukaryotic organisms Direct non-replicative and replicative mechanisms of transpositions The concept of horizontal transposon transfer and their role in structural rearrangements (ectopic recombination) and in genome evolution.

5. Study of the structure and function of the gene.

Elements of genetic analysis. Cis-trans complementation test. Genetic mapping using conjugation, transduction and transformation. Construction of genetic maps. Fine genetic mapping. Physical analysis of the gene structure. heteroduplex analysis. Restriction analysis. Sequencing methods. polymerase chain reaction. Revealing the function of a gene.

6. Regulation of gene expression. Concepts of operon and regulon. Control at the level of transcription initiation. Promoter, operator and regulatory proteins. Positive and negative control of gene expression. Control at the level of transcription termination. Catabolite-controlled operons: models of lactose, galactose, arabinose and maltose operons. Attenuator-controlled operons: a model of the tryptophan operon. Multivalent regulation of gene expression. Global systems of regulation. Regulatory response to stress. post-transcriptional control. signal transduction. RNA-mediated regulation: small RNAs, sensor RNAs.

7. Fundamentals of genetic engineering. Restriction enzymes and modifications. Isolation and cloning of genes. Vectors for molecular cloning. Principles of construction of recombinant DNA and their introduction into recipient cells. Applied aspects of genetic engineering.

A). Main literature:

1. Watson J., Tooze J., Recombinant DNA: A Brief Course. – M.: Mir, 1986.

2. Genes. – M.: Mir. 1987.

3. Molecular biology: structure and biosynthesis of nucleic acids. / Ed. . - M. Higher school. 1990.

4. , – Molecular biotechnology. M. 2002.

5. Spirin ribosomes and protein biosynthesis. - M .: Higher school, 1986.

b). Additional literature:

1. Hesin of the genome. – M.: Science. 1984.

2. Rybchin of genetic engineering. - St. Petersburg: St. Petersburg State Technical University. 1999.

3. Patrushev genes. – M.: Nauka, 2000.

4. Modern microbiology. Prokaryotes (in 2 vols.). – M.: Mir, 2005.

5. M. Singer, P. Berg. Genes and genomes. – M.: Mir, 1998.

6. Shchelkunov engineering. - Novosibirsk: From Sib. Univ., 2004.

7. Stepanov biology. Structure and functions of proteins. - M.: V. Sh., 1996.

(Molekular biologe/-biologin)

• Type

  Profession after graduation

• Salary

  3667-5623 € per month

Molecular biologists study molecular processes as the basis of all life processes. Based on the results obtained, they develop concepts for the use of biochemical processes, for example in medical research and diagnostics or in biotechnology. In addition, they may be involved in pharmaceutical product manufacturing, product development, quality assurance, or pharmaceutical consulting.

Responsibilities of a Molecular Biologist

Molecular biologists can work in different fields. For example, they concern the use of research results for production in areas such as genetic engineering, protein chemistry or pharmacology (drug discovery). In the chemical and pharmaceutical industries, they facilitate the transfer of newly developed products from research into production, product marketing and user advice.

In scientific research, molecular biologists study the chemical-physical properties of organic compounds, as well as chemical processes (in the field of cellular metabolism) in living organisms and publish the results of research. In higher educational institutions they teach students, prepare for lectures and seminars, check written work and administer examinations. Independent scientific activity is possible only after obtaining a master's and doctoral degree.

Where Do Molecular Biologists Work?

Molecular biologists find work, such as

• in research institutes, e.g. in the fields of science and medicine
• in higher education institutions
• in the chemical-pharmaceutical industry
• in departments of environmental protection

Molecular Biologist Salary

The salary level received by Molecular Biologists in Germany is

• from 3667€ to 5623€ per month

(according to various statistical offices and employment services in Germany)

Tasks and Responsibilities of a Molecular Biologist in Detail

What is the essence of the profession Molecular Biologist

Molecular biologists study molecular processes as the basis of all life processes. Based on the results obtained, they develop concepts for the use of biochemical processes, for example in medical research and diagnostics or in biotechnology. In addition, they may be involved in pharmaceutical product manufacturing, product development, quality assurance, or pharmaceutical consulting.

Vocation Molecular Biology

Molecular biology or molecular genetics deals with the study of the structure and biosynthesis of nucleic acids and the processes involved in the transmission and realization of this information in the form of proteins. This makes it possible to understand painful disorders of these functions and, possibly, to cure them with the help of gene therapy. There are interfaces for biotechnology and genetic engineering that create simple organisms, such as bacteria and yeast, to make substances of pharmacological or commercial interest available on an industrial scale through targeted mutations.

Theory and Practice of Molecular Biology

The chemical-pharmaceutical industry offers numerous areas of employment for molecular biologists. In industrial settings, they analyze biotransformation processes or develop and improve processes for the microbiological production of active ingredients and pharmaceutical intermediates. In addition, they are involved in the transition of newly developed products from research to production. By performing inspection tasks, they ensure that production facilities, equipment, analytical methods and all steps in the production of sensitive products such as pharmaceuticals always meet the required quality standards. In addition, molecular biologists advise users on the use of new products.

Management positions often require a master's program.

Molecular Biologists in Research and Education

In the field of science and research, molecular biologists deal with topics such as the recognition, transport, folding, and codification of proteins in a cell. The results of research, which are the basis for practical applications in various fields, are published and thus made available to other scientists and students. At conferences and congresses, they discuss and present the results of scientific activities. Molecular biologists give lectures and seminars, supervise scientific work, and administer examinations.

Independent scientific activity requires a master's degree and a doctorate.