Molecular biology - Molecular biology. Biochemistry and molecular biology - where to study? Applied value of molecular biology

(Molekular biologe/-biologin)

• Type of

  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 areas. 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 organic compounds, as well as chemical processes (in the field of cellular metabolism) in living organisms and publish research results. In institutions of higher learning, they teach students, prepare for lectures and seminars, check written work, and administer examinations. Independent scientific activity only possible 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 verification 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.

Molecular biology has experienced a period of rapid development of its own research methods, which now differs from biochemistry. These include, in particular, methods of genetic engineering, cloning, artificial expression, and gene knockout. Since DNA is the material carrier of genetic information, molecular biology has become much closer to genetics, and molecular genetics was formed at the junction, which is both a section of genetics and molecular biology. Just as molecular biology makes extensive use of viruses as a research tool, virology uses the methods of molecular biology to solve its problems. Computer technology is involved in the analysis of genetic information, in connection with which new areas of molecular genetics have appeared, which are sometimes considered special disciplines: bioinformatics, genomics and proteomics.

The history of development

This seminal discovery was prepared by a long phase of research into the genetics and biochemistry of viruses and bacteria.

In 1928, Frederick Griffith first showed that an extract of heat-killed pathogenic bacteria could transfer the trait of pathogenicity to benign bacteria. The study of bacterial transformation further led to the purification of the disease agent, which, contrary to expectations, turned out to be not a protein, but a nucleic acid. The nucleic acid itself is not dangerous, it only carries the genes that determine the pathogenicity and other properties of the microorganism.

In the 50s of the XX century, it was shown that bacteria have a primitive sexual process, they are able to exchange extrachromosomal DNA, plasmids. The discovery of plasmids, as well as transformations, formed the basis of the plasmid technology common in molecular biology. Another important discovery for the methodology was the discovery at the beginning of the 20th century of bacterial viruses, bacteriophages. Phages can also transfer genetic material from one bacterial cell to another. Infection of bacteria by phages leads to a change in the composition of bacterial RNA. If, without phages, the composition of RNA is similar to the composition of bacterial DNA, then after infection, RNA becomes more similar to bacteriophage DNA. Thus, it was found that the structure of RNA is determined by the structure of DNA. In turn, the rate of protein synthesis in cells depends on the amount of RNA-protein complexes. This is how it was formulated central dogma of molecular biology: DNA ↔ RNA → protein.

The further development of molecular biology was accompanied by both the development of its methodology, in particular, the invention of a method for determining the nucleotide sequence of DNA (W. Gilbert and F. Sanger, Nobel Prize in Chemistry in 1980), and new discoveries in the field of research into the structure and functioning of genes (see. History of genetics). By the beginning of the 21st century, data were obtained on the primary structure of all human DNA and a number of other organisms, the most important for medicine, agriculture and scientific research, which led to the emergence of several new areas in biology: genomics, bioinformatics, etc.

see also

• Molecular biology (journal)
• Transcriptomics
• Molecular paleontology
• EMBO - European Organization for Molecular Biology

Literature

• Singer M., Berg P. Genes and genomes. - Moscow, 1998.
• Stent G., Kalindar R. Molecular genetics. - Moscow, 1981.
• Sambrook J., Fritsch E.F., Maniatis T. Molecular Cloning. - 1989.
• Patrushev L.I. Expression of genes. - M.: Nauka, 2000. - 000 p., ill. ISBN 5-02-001890-2

Links

Wikimedia Foundation. 2010 .

• Ardatovsky district of the Nizhny Novgorod region
• Arzamas district of the Nizhny Novgorod region

See what "Molecular Biology" is in other dictionaries:

MOLECULAR BIOLOGY- studies the basics. properties and manifestations of life at the molecular level. The most important directions in M. b. are studies of the structural and functional organization of the genetic apparatus of cells and the mechanism for the implementation of hereditary information ... ... Biological encyclopedic dictionary

MOLECULAR BIOLOGY- explores the basic properties and manifestations of life at the molecular level. Finds out how and to what extent the growth and development of organisms, the storage and transmission of hereditary information, the conversion of energy in living cells, and other phenomena are due to ... Big Encyclopedic Dictionary

MOLECULAR BIOLOGY Modern Encyclopedia

MOLECULAR BIOLOGY- MOLECULAR BIOLOGY, the biological study of the structure and function of the MOLECULES that make up living organisms. The main areas of study are physical and Chemical properties proteins and NUCLEIC ACIDS such as DNA. see also… … Scientific and technical encyclopedic dictionary

molecular biology- a section of biol., which explores the basic properties and manifestations of life at the molecular level. Finds out how and to what extent the growth and development of organisms, the storage and transmission of hereditary information, the conversion of energy in living cells and ... ... Dictionary of microbiology

molecular biology- — Topics of biotechnology EN molecular biology … Technical Translator's Handbook

Molecular biology- MOLECULAR BIOLOGY, explores the basic properties and manifestations of life at the molecular level. Finds out how and to what extent the growth and development of organisms, the storage and transmission of hereditary information, the conversion of energy in living cells and ... ... Illustrated Encyclopedic Dictionary

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 end goal of this is…… Great Soviet Encyclopedia

MOLECULAR BIOLOGY- studies the phenomena of life at the level of macromolecules (ch. arr. proteins and nucleic acids) in cell-free structures (ribosomes, etc.), in viruses, and also in cells. M.'s purpose. establishing the role and mechanism of functioning of these macromolecules based on ... ... Chemical Encyclopedia

molecular biology- explores the basic properties and manifestations of life at the molecular level. Finds out how and to what extent the growth and development of organisms, the storage and transmission of hereditary information, the conversion of energy in living cells and other phenomena ... ... encyclopedic Dictionary

Books

• Molecular biology of the cell. Problem Book, J. Wilson, T. Hunt. The book of American authors is an appendix to the 2nd edition of the textbook `Molecular Biology of the Cell` by B. Alberts, D. Bray, J. Lewis and others. Contains questions and tasks, the purpose of which is to deepen ...

A molecular biologist is a medical researcher whose mission is nothing less than saving humanity from dangerous diseases. Among such diseases, for example, oncology, which today has become one of the main causes of death in the world, is only slightly inferior to the leader - cardiovascular diseases. New methods of early diagnosis of oncology, prevention and treatment of cancer are a priority task of modern medicine. Molecular biologists in the field of oncology develop antibodies and recombinant (genetically engineered) proteins for early diagnosis or targeted drug delivery in the body. Specialists in this field use the latest achievements of science and technology to create new organisms and organic matter for the purpose of their further use in research and clinical activities. Among the methods used by molecular biologists are cloning, transfection, infection, polymerase chain reaction, gene sequencing, and others. One of the companies interested in molecular biologists in Russia is PrimeBioMed LLC. The organization is engaged in the production of antibodies-reagents for the diagnosis of cancer. Such antibodies are mainly used to determine the type of tumor, its origin and malignancy, that is, the ability to metastasize (spread to other parts of the body). Antibodies are applied to thin sections of the examined tissue, after which they bind in cells to certain proteins - markers that are present in tumor cells, but absent in healthy ones and vice versa. Depending on the results of the study, further treatment is prescribed. PrimeBioMed's clients include not only medical, but also scientific institutions, since antibodies can also be used to solve research problems. In such cases, unique antibodies capable of binding to the studied protein can be produced for a specific task by special order. Another promising direction of the company's research is targeted (targeted) delivery of drugs in the body. AT this case antibodies are used as transport: with their help, drugs are delivered directly to the affected organs. Thus, the treatment becomes more effective and has fewer negative consequences for the body than, for example, chemotherapy, which affects not only cancer cells, but also other cells. The profession of a molecular biologist is expected to become more and more in demand in the coming decades: with an increase in the average life expectancy of a person, the number of oncological diseases will increase. Early detection of tumors and innovative methods of treatment with the help of substances obtained by molecular biologists will save lives and improve its quality for a huge number of people.

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 nucleic acids. Chemical structure, spatial structure and physical properties of 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-replicative 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 type 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.: graduate 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.

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 begin 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 molecular structure and biological, physical features 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.

AT 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."

AT 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. AT 1951 and 1952 years, the scientist determined the complete sequence of two polypeptide chains - bovine insulin AT(30 amino acid residues) and BUT(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).

AT 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: a reverse flow of information cannot occur, a 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 within 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 for the further development of molecular biology, it became necessary special methods. 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

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 the possibilities of research and study of the genetic nature of human diseases in order to take the necessary measures in advance and avoid diseases.

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 enjoys great popularity today.

Similar methods are widely applicable practically all over the world, including in Russia. Due to scientific progress, there is an introduction of such methods into medical research and medical practice in general.

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 the 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 methods of biotechnology are used for recycling waste disposal, cleaning Wastewater, exhaust air and sanitation of soils.
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 even identical not only in outward signs but also in terms of 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. AT vivo 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 into 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, ETH Zurich researchers have developed a method that can simultaneously modify 25 genes in a cell.

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