From Big Medical Encyclopedia

MOLECULAR BIOLOGY late lat. molecula, diminutive from armor. moles weight; biology) — the medicobiological science studying the phenomena of life at the level of biological macromolecules — proteins and nucleic acids, such simple systems, as acellular structures, viruses and, as a limit — at the level of a cell. The most part of such objects is the lifeless or allocated with elementary manifestations life. Situation M. in system biol, sciences is defined by ideas of the structural levels of living matter, i.e. evolutionarily developed life forms which are beginning with prebiotichesky steps and coming to an end in complex systems: small organic molecules — macromolecules — a cell and subcellular structures — an organism etc., respectively the Crimea are under construction also levels of knowledge. Historically M. it was created as a result of a research of biological macromolecules owing to what M. is considered as the section biochemistry (see). M. is at the same time the boundary science which arose on a joint of biochemistry biophysics (see), organic chemistry (see), cytology (see) and geneticists (see). M.'s idea. consists in disclosure of elementary mechanisms of basic processes of life activity — heredities (see), variability (see), the movements, etc. — through a research biol, macromolecules. Molecular biol. representations found the fertile field especially in genetics — arose molecular genetics (see), and results exactly here were achieved, to-rye would promote M.'s development. and to recognition of its principles. M.'s representations. have the heuristic (cognitive) value since at all levels of development of living matter exist and macromolecules work biol — proteins (see) and nucleic acids (see). For this reason of border of M. difficult opredelima: it appears pervasive science.

The name «molecular biology» belongs to the English crystallographer of Astberi (W. T. Astbury). Formal date of emergence of M. consider 1953 when J. Watson and T. Shout established structure of DNA and stated the assumption of the mechanism which was confirmed later it to the replication which is the cornerstone of heredity. But at least since 1944, since Avery's works (O. Th. Avery), collected the facts indicating a genetic role of DNA; N. K. Koltsov stated the idea about matrix synthesis in very clear form in 1928; studying of molecular bases of muscular contraction began with W. A. Engelgardt and M. N. Lyubimova's works published in 1939 — 1942 by M. developed also in the field of theory of evolution and a systematics. In the USSR A. N. Belozersky was an initiator of studying nucleinic to - t and researches on molecular bases of evolution.

Distinctive feature of M. consists in the nature of observations, in its methodical receptions and creation of an experiment. M. forced biologists to look at a material basis of life activity in a new way. For a molecular biol. researches comparison biol, functions with chemical and physical is characteristic. characteristics (properties) of biopolymers and in particular with their space structure.

Nucleinic to - t and their behavior in a cell the principle of a complementarity of the bases in dvukhtyazhevy structures nucleinic to - t, established in 1953 by J. Watson and T is essential for understanding of patterns of a structure. Shout, Recognition of value of the space relations found the expression in idea of the complementarity of surfaces of macromolecules and molecular complexes making a necessary condition of manifestation of the weak forces operating only at short distances and promoting creation morfol, a variety biol. structures, their functional mobility. These weak forces participate in formation of enzyme — complexes substrate, antigen — an antibody, hormone — a receptor, etc., in the phenomena of self-assembly biol, structures, napr, ribosomes, in formation of base pairs in molecules nucleinic to - t and in that similar processes.

M. directed attention of biologists to the simple, costing at borders life objects, entered into an arsenal biol, researches of the idea and exact methods of chemistry and physics. Mutational process received interpretation at molecular level as loss, an insert and movement of pieces of DNA, replacement of a base pair in functionally significant pieces of a genome (see. Mutation ). Phenomena mutagenesis (see), thus, were translated into chemical language. Thanks to methods M. molecular bases of such genetic processes at prokariot as were opened recombination (see), transductions (see), transformation (see), transfection, sexduction. Considerable success in studying of a structure of chromatin and chromosomes of eukaryotes is achieved; improvement of methods of cultivation and hybridization of zooblasts created a possibility of development geneticists of somatic cells (see). Regulation of DNA replication found the expression in idea of replicon F. Jacob and S. Brenner.

In the field of biosynthesis of protein the so-called central postulate characterizing the following movement of genetic information was established: DNA —> information RNA —> protein. According to this postulate, protein is some kind of information valve interfering return of information to the RNA and DNA level. In development of M. in 1970 by H. Temin and Baltimore (D. Baltimore) the phenomenon of reverse transcription (in the nature synthesis of DNA happens at oncogenous RNA-containing of viruses by means of special enzyme — the return transcriptase) was opened. Protein syntheses and nucleinic to - t happen as matrix sintez, the matrix (template) — an initial polymeric molecule is necessary for their course, edges are predetermined by the sequence of nucleotides (amino acids) in the synthesizable copy. Such matrixes at replication and a transcription is DNA and during the broadcasting — information RNA. Genetic code (see) formulates the way «records» of hereditary information in information RNA, in other words, he will coordinate the sequence of nucleotides in nucleinic to-takh and amino acids in proteins. The transcription — the synthesis of information RNA on a matrix of DNA catalyzed by RNA polymerases is connected with biosynthesis of protein; broadcasting — the synthesis of protein on the information RNA connected with a ribosome proceeding on very difficult mechanism in Krom tens of auxiliary proteins and acceptor RNA participate (see. Ribosomes ). Regulation of proteinaceous synthesis is most studied at the level of a transcription and formulated in F. Jacob's idea and J. Monod of an operon, proteins-repressorakh, allosteric effect, positive and negative regulation. Diverse according to the contents and even less complete, than previous, the section M. a number of problems of fundamental and applied character is. The reparation of the damages of a genome caused by short-wave radiation concerns to them mutagens (see) and other influences. The big independent area is made by the researches of the mechanism of effect of enzymes based on ideas of three-dimensional structure of proteins and a role of weak chemical interactions. M. found out many details of a structure and development of viruses, in particular bacteriophages. Studying of haemo globins at the persons suffering sickemia (see) and others hemoglobinopathies (see), laid the foundation for studying of a structural basis of «molecular diseases», inborn «errors» of metabolism (see. Hereditary diseases ). The latest branch of M. — genetic engineering (see) — develops methods of designing of hereditary structures in the form of molecules of recombinant DNA.

In a molecular biol. experiences various ways find application chromatography (see) and ultracentrifuging (see), X-ray crystallographic analysis (see), submicroscopy (see), molecular spectroscopy (electronic paramagnetic and nuclear magnetic resonance). Use of synchrotron (magnetic and brake) radiation, diffraction of neutrons, messbauerovsky spectroscopy, the laser equipment is begun. In experiments model systems, receiving mutations are widely applied. Use radioactive and (in a smaller measure) heavy isotopes would make in M. usual analytical method, just as use of mathematical methods and COMPUTER. If earlier molecular biologists were guided hl. obr. on physical. the methods created for a research of polymers Nibiolum. origins, all is now observed the amplifying tendency to use of chemical methods.

For M.'s development. in the USSR the resolution of the Central Committee of the CPSU and Council of ministers of the USSR «About measures for acceleration of development of molecular biology and molecular genetics and use of their achievements in the national economy», published on May 20, 1974 was of great importance. Researches are coordinated by Interdepartmental scientific and technical council on problems of molecular biology and molecular genetics at GKNT of Council of ministers of the USSR and Academy of Sciences of the USSR, Scientific council on problems of molecular biology of Academy of Sciences of the USSR, similar councils of AN of federal republics and industry academies. The Molecular biology magazine is issued (since 1967) and the abstract magazine with the same name. Researches on M. are conducted in in-ta of Academy of Sciences of the USSR, the USSR Academy of Medical Sciences, republican academies of Sciences, Glavmikrobioprom, in higher educational institutions of the country. In the socialist countries many laboratories of such profile work. In Europe the European Molecular and Biological Organization (EMBO), the European Molecular and Biological Laboratory (EMBL) in Heidelberg, the European Molecular and Biological Conference (EMBC) work. Large specialized laboratories in the USA, France, Great Britain, Germany and other countries work.

The special periodicals devoted to problems M., abroad: «Journal of Molecular Biology», «Nucleic Acids Research», «Molecular Biology Reports», «Gene».

Reviews on M. are published in the Molecular biology series of VINITI, in «Progress in Nucleic Acids Research and Molecular Biology», «Progress in Biophysics and Molecular Biology», «Annual Rewiew of Biochemistry», the editions «Cold Spring Harbor Symposia on Quantitative Biology».

Bibliography: Ashmarin I. P. Molecular biology, L., 1977; Belozersk A. N. Molecular biology — a new step of knowledge of the nature, M., 1970; Bresler S. E. Molecular biology, L., 1973; Koltsov N. K. Hereditary molecules, Bulletin Mosk. about-va ispyt. nature, otd. biol., t. 70, century 4, page 75, 1965; October and science, under the editorship of A. P. Alexandrov, etc., page 393, 417, M., 1977; Severin S. E. Modern problems of physical and chemical biology, in book: 250 years of Academy of Sciences of the USSR, page 332, M., 1977; Watson Dzh. Molecular biology: a gene, the lane with English, M., 1978; Engel-g and r d V. A t. Molecular biology, in book: Development biol, in the USSR, under the editorship of B. E. Bykhovsky, page 598, M., 1967.

A. A. Bayev.