Genetic engineering short message. Genetic engineering

Encyclopedic YouTube

1 / 5
Genetic engineering serves to obtain the desired qualities of a changeable or genetically modified organism. Unlike traditional selection, during which the genotype is subject to changes only indirectly, genetic engineering allows direct intervention in the genetic apparatus using the technique of molecular cloning. Examples of the application of genetic engineering are the production of new genetically modified varieties of grain crops, the production of human insulin using genetically modified bacteria, the production of erythropoietin in cell culture or new breeds of experimental mice for scientific research.

The basis of the microbiological, biosynthetic industry is the bacterial cell. The cells necessary for industrial production are selected according to certain characteristics, the most important of which is the ability to produce, synthesize, in the maximum possible quantities, a certain compound - an amino acid or an antibiotic, a steroid hormone or an organic acid. Sometimes you need to have a microorganism that can, for example, use oil or wastewater as “food” and process it into biomass or even protein quite suitable for feed additives. Sometimes we need organisms that can develop at elevated temperatures or in the presence of substances that are certainly lethal to other types of microorganisms.
The task of obtaining such industrial strains is very important; for their modification and selection, numerous methods of actively influencing the cell have been developed - from treatment with potent poisons to radioactive irradiation. The goal of these techniques is one - to achieve changes in the hereditary, genetic apparatus of the cell. Their result is the production of numerous mutant microbes, from hundreds and thousands of which scientists then try to select the most suitable for a particular purpose. The creation of techniques for chemical or radiation mutagenesis was an outstanding achievement in biology and is widely used in modern biotechnology.
But their capabilities are limited by the nature of the microorganisms themselves. They are not able to synthesize a number of valuable substances that accumulate in plants, primarily in medicinal and essential oil plants. They cannot synthesize substances that are very important for the life of animals and humans, a number of enzymes, peptide hormones, immune proteins, interferons, and many simpler compounds that are synthesized in the bodies of animals and humans. Of course, the possibilities of microorganisms are far from exhausted. Of the entire abundance of microorganisms, only a tiny fraction has been used by science, and especially by industry. For the purposes of selection of microorganisms, of great interest are, for example, anaerobic bacteria that can live in the absence of oxygen, phototrophs that use light energy like plants, chemoautotrophs, thermophilic bacteria that can live at temperatures, as recently discovered, about 110 ° C, etc.
And yet the limitations of “natural material” are obvious. They have tried and are trying to get around the restrictions with the help of cell and tissue cultures of plants and animals. This is a very important and promising path, which is also being implemented in biotechnology. Over the past few decades, scientists have developed methods by which individual tissue cells of a plant or animal can be made to grow and reproduce separately from the body, like bacterial cells. This was an important achievement - the resulting cell cultures are used for experiments and for the industrial production of certain substances that cannot be obtained using bacterial cultures.
Another direction of research is the removal from DNA of genes that are unnecessary for coding proteins and the functioning of organisms and the creation of artificial organisms with a “truncated set” of genes based on such DNA. This makes it possible to dramatically increase the resistance of modified organisms to viruses.

History of development and achieved level of technology

In the second half of the 20th century, several important discoveries and inventions were made that underlie genetic engineering. Many years of attempts to “read” the biological information that is “written” in genes have been successfully completed. This work was started by the English scientist Frederick Sanger and the American scientist Walter Gilbert (Nobel Prize in Chemistry 1980). As is known, genes contain information-instructions for the synthesis of RNA molecules and proteins, including enzymes, in the body. To force a cell to synthesize new substances that are unusual for it, it is necessary that the corresponding sets of enzymes be synthesized in it. And for this it is necessary to either purposefully change the genes located in it, or introduce new, previously absent genes into it. Changes in genes in living cells are mutations. They occur under the influence, for example, of mutagens - chemical poisons or radiation. But such changes cannot be controlled or directed. Therefore, scientists have focused their efforts on trying to develop methods for introducing new, very specific genes needed by humans into cells.
The main stages of solving a genetic engineering problem are as follows:
1. Obtaining an isolated gene.
2. Introduction of a gene into a vector for transfer into the body.
3. Transfer of a vector with a gene into the modified organism.
4. Transformation of body cells.
5. Selection of genetically modified organisms ( GMO) and eliminating those that were not successfully modified.
The process of gene synthesis is now very well developed and even largely automated. There are special devices equipped with computers, in the memory of which programs for the synthesis of various nucleotide sequences are stored. This apparatus synthesizes DNA segments up to 100-120 nitrogen bases in length (oligonucleotides). A technique has become widespread that makes it possible to use the polymerase chain reaction to synthesize DNA, including mutant DNA. A thermostable enzyme, DNA polymerase, is used in it for template DNA synthesis, for which artificially synthesized pieces of nucleic acid - oligonucleotides - are used as seeds. The enzyme reverse transcriptase allows, using such primers, to synthesize DNA on a template of RNA isolated from cells. The DNA synthesized in this way is called complementary DNA (RNA) or cDNA. An isolated, "chemically pure" gene can also be obtained from a phage library. This is the name of a bacteriophage preparation, into the genome of which random fragments from the genome or cDNA are built in, reproduced by the phage along with all its DNA.
The technique of introducing genes into bacteria was developed after Frederick Griffith discovered the phenomenon of bacterial transformation. This phenomenon is based on a primitive sexual process, which in bacteria is accompanied by the exchange of small fragments of non-chromosomal DNA, plasmids. Plasmid technologies formed the basis for the introduction of artificial genes into bacterial cells.
Significant difficulties were associated with the introduction of a ready-made gene into the hereditary apparatus of plant and animal cells. However, in nature there are cases when foreign DNA (of a virus or bacteriophage) is included in the genetic apparatus of a cell and, with the help of its metabolic mechanisms, begins to synthesize “its” protein. Scientists studied the features of the introduction of foreign DNA and used it as a principle for introducing genetic material into a cell. This process is called transfection.
If unicellular organisms or multicellular cell cultures are subject to modification, then at this stage cloning begins, that is, the selection of those organisms and their descendants (clones) that have undergone modification. When the task is to obtain multicellular organisms, cells with an altered genotype are used for vegetative propagation of plants or introduced into the blastocysts of a surrogate mother when it comes to animals. As a result, cubs are born with a changed or unchanged genotype, among which only those that exhibit the expected changes are selected and crossed with each other.

Application in scientific research

Although on a small scale, genetic engineering is already being used to give women with some types of infertility a chance to get pregnant. For this purpose, eggs from a healthy woman are used. As a result, the child inherits the genotype from one father and two mothers.
However, the possibility of making more significant changes to the human genome faces a number of serious ethical problems. In 2016, in the United States, a group of scientists received approval for clinical trials of a method of treating cancer using the patient’s own immune cells, subjected to genetic modification using CRISPR / Cas9 technology.

Cell engineering

Cellular engineering is based on the cultivation of plant and animal cells and tissues capable of producing substances necessary for humans outside the body. This method is used for clonal (asexual) propagation of valuable plant forms; to obtain hybrid cells that combine the properties of, for example, blood lymphocytes and tumor cells, which makes it possible to quickly obtain antibodies.

Genetic engineering in Russia

It is noted that after the introduction of state registration of GMOs, the activity of some public organizations and individual State Duma deputies, trying to prevent the introduction of innovative biotechnologies in Russian agriculture, has noticeably increased. More than 350 Russian scientists signed an open letter from the Society of Scientific Workers in support of the development of genetic engineering in the Russian Federation. The open letter notes that a ban on GMOs in Russia will not only harm healthy competition in the agricultural market, but will lead to a significant lag in food production technologies, increased dependence on food imports, and will undermine the prestige of Russia as a state in which a course towards innovative development has been officially announced [ the significance of the fact? ] .

see also

Notes
1. Alexander Panchin Beating God // Popular mechanics. - 2017. - No. 3. - P. 32-35. - URL: http://www.popmech.ru/magazine/2017/173-issue/
2. In vivo genome editing using a high-efficiency TALEN system(English) . Nature. Retrieved January 10, 2017.
3. Elements - science news: monkeys cured of colorblindness using gene therapy (undefined) (September 18, 2009). Retrieved January 10, 2017.
Send your good work in the knowledge base is simple. Use the form below

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

Posted on http://www.allbest.ru/

Genetic engineering, a set of methods of biochemistry and molecular genetics, with the help of which the directed combined genetic information of any organisms is carried out.

Genetic engineering makes it possible to overcome natural interspecies barriers that prevent the exchange of genetic information between taxonomically distant species of organisms, and to create cells and organisms with combinations of genes that do not exist in nature, with specified inherited properties. The main object of genetic engineering influence is the carrier of genetic information - deoxyribonucleic acid (DNA), the molecule of which usually consists of two chains. The strict specificity of the pairing of purine and pyrimidine bases determines the property of complementarity - the mutual correspondence of nucleotides in two chains. The creation of new combinations of genes turned out to be possible due to the fundamental similarity in the structure of DNA molecules in all types of organisms, and in fact, the universality of the genetic code ensures the expression of foreign genes (manifestation of their functional activity) in any type of cell. This was also facilitated by the accumulation of knowledge in the field of nucleic acid chemistry, the identification of molecular features of the organization and functioning of genes (including the establishment of mechanisms for regulating their expression and the possibility of subordinating genes to the action of “foreign” regulatory elements), the development of DNA sequencing methods, and the discovery of the polymerase chain reaction , which made it possible to quickly synthesize any DNA fragment. Important prerequisites for the emergence of genetic engineering were: the discovery of plasmids capable of autonomous replication and transfer from one bacterial cell to another, and the phenomenon of transduction - the transfer of certain genes by bacteriophages, which made it possible to formulate the idea of vectors: molecules - gene carriers. Enzymes involved in the transformation of nucleic acids played a huge role in the development of genetic engineering methodology: restriction enzymes (recognize strictly defined sequences - sites - in DNA molecules and “cut” the double strand in these places), DNA ligases (covalently bind individual DNA fragments), reverse transcriptase (synthesizes a complementary copy of DNA, or cDNA, on an RNA template), etc. Only with their availability, the creation of artificial structures has become a technically feasible task. Enzymes are used to obtain individual DNA fragments (genes) and create molecular hybrids - recombinant DNA (recDNA) based on the DNA of plasmids and viruses. The latter deliver the desired gene into the host cell, ensuring its reproduction there (cloning) and the formation of the final gene product (its expression).

Principles of creationanalysis of recombinant DNA molecules

The term “Genetic engineering” became widespread after in 1972 P. Berg and his colleagues first obtained recombinant DNA, which was a hybrid in which DNA fragments of the bacterium Escherichia coli, its virus (bacteriophage a) and the DNA of the simian virus SV40 were combined. In 1973, S. Cohen and coworkers used the pSC101 plasmid and a restriction enzyme (EcoRI), which opens it in one place so that short complementary single-stranded “tails” (usually 4 to 6 nucleotides) are formed at the ends of a double-stranded DNA molecule. They were called "sticky" because they could mate (stick together, as it were) with each other. When such DNA was mixed with fragments of foreign DNA treated with the same restriction enzyme and having the same sticky ends, new hybrid plasmids were obtained, each of which contained at least one fragment of foreign DNA inserted into the EcoRI site of the plasmid. It became obvious that fragments of various foreign DNA obtained from both microorganisms and higher eukaryotes can be inserted into such plasmids.

The main modern strategy for obtaining recDNA is as follows:

1) DNA fragments belonging to another organism containing certain genes or artificially obtained nucleotide sequences of interest to the researcher are inserted into the DNA of a plasmid or virus that can reproduce independently of the chromosome;

2) The resulting hybrid molecules are introduced into sensitive prokaryotic or eukaryotic cells, where they are replicated (multiplied, amplified) together with DNA fragments built into them;

3) Cell clones are selected in the form of colonies on special nutrient media (or viruses in the form of clearing zones - plaques on a layer of continuous growth of bacterial cells or animal tissue cultures) containing the required types of recDNA molecules and subject them to comprehensive structural and functional studies.

To facilitate the selection of cells in which recDNA is present, vectors containing one or more markers are used. In plasmids, for example, antibiotic resistance genes can serve as such markers (cells containing recDNA are selected based on their ability to grow in the presence of a particular antibiotic). RecDNA carrying the desired genes is selected and introduced into recipient cells. From this moment, molecular cloning begins - obtaining copies of DNA rivers, and, consequently, copies of target genes in its composition. Only if it is possible to separate all transfected or infected cells will each clone be represented by a separate colony of cells and contain a certain amount of DNA. At the final stage, clones containing the desired gene are identified. One is based on the fact that the insertion into a DNA stream determines some unique property of the cell containing it (for example, the expression product of the inserted gene). In molecular cloning experiments, 2 basic principles are observed: none of the cells where DNA rivers are cloned should receive more than one plasmid molecule or viral particle; the latter must be capable of replication.

A wide range of plasmid and viral DNAs are used as vector molecules in genetic engineering. The most popular cloning vectors contain several genetic markers and have one site of action for different restriction enzymes. Such requirements, for example, are best met by the plasmid pBR322, which was constructed from an originally naturally occurring plasmid using methods used when working with recDNA; it contains genes for resistance to ampicillin and tetracycline, as well as one recognition site for 19 different restriction enzymes. A special case of cloning vectors are expression vectors, which, along with amplification, ensure correct and effective expression of foreign genes in recipient cells. In some cases, molecular vectors can ensure the integration of foreign DNA into the genome of a cell or virus (they are called integrative vectors).

One of the most important tasks of genetic engineering is the creation of strains of bacteria or yeast, cell lines of animal or plant tissues, as well as transgenic plants and animals that would ensure effective expression of the genes cloned in them. A high level of protein production is achieved if genes are cloned in multicopy vectors, since in this case the target gene will be present in large quantities in the cell. It is important that the DNA coding sequence is under the control of a promoter that is effectively recognized by the cell's RNA polymerase, and that the resulting mRNA is relatively stable and efficiently translated. In addition, a foreign protein synthesized in recipient cells should not be subject to rapid degradation by intracellular proteases. When creating transgenic animals and plants, tissue-specific expression of the introduced target genes is often achieved.

Since the genetic code is universal, the possibility of gene expression is determined only by the presence in its composition of signals for initiation and termination of transcription and translation, correctly recognized by the host cell. Since most genes of higher eukaryotes have a discontinuous exon-intron structure, as a result of the transcription of such genes, a template RNA precursor is formed, from which, during subsequent splicing, non-coding sequences - introns - are cleaved and mature mRNA is formed. Such genes cannot be expressed in bacterial cells where there is no splicing system. In order to overcome this obstacle, a DNA copy (cDNA) is synthesized on mature mRNA molecules using reverse transcriptase, to which a second strand is added using DNA polymerase. Such DNA fragments corresponding to the coding sequence of the genes (no longer separated by introns) can be inserted into a suitable molecular vector.

Knowing the amino acid sequence of the target polypeptide, it is possible to synthesize the nucleotide sequence encoding it, obtaining a gene equivalent, and insert it into the corresponding expression vector. When creating an equivalent gene, they usually take into account the degeneracy of the genetic code (20 amino acids are encoded by 61 codons) and the frequency of occurrence of codons for each amino acid in the cells into which this gene is planned to be introduced, since the composition of codons can differ significantly in different organisms. Correctly selected codons can significantly increase the production of the target protein in the recipient cell.

The Importance of Genetic Engineering

Genetic engineering has significantly expanded the experimental boundaries of molecular biology, since it has become possible to introduce foreign DNA into various types of cells and study its functions. This made it possible to identify general biological patterns of organization and expression of genetic information in various organisms. This approach has opened up prospects for creating fundamentally new microbiological producers of biologically active substances, as well as animals and plants carrying functionally active foreign genes. Many previously inaccessible biologically active human proteins, including interferons, interleukins, peptide hormones, blood factors, began to be produced in large quantities in the cells of bacteria, yeast or mammals and are widely used in medicine. Moreover, it has become possible to artificially create genes encoding chimeric polypeptides that have the properties of two or more natural proteins. All this gave a powerful impetus to the development of biotechnology.

The main objects of genetic engineering are the bacteria Escherichia coli (Escherichia coli) and Bacillus subtilis (bacillus subtilis), baker's yeast Saccharomices cereuisiae, and various mammalian cell lines. The range of objects of genetic engineering influence is constantly expanding. Research areas on the creation of transgenic plants and animals are intensively developing. The latest generations of vaccines against various infectious agents are created using genetic engineering methods (the first of them was created based on yeast that produces the surface protein of the human B virus). Much attention is paid to the development of cloning vectors based on mammalian viruses and their use to create live polyvalent vaccines for veterinary and medical needs, as well as molecular vectors for gene therapy of cancer tumors and hereditary diseases. A method has been developed for directly introducing recDNA into the body of animals and humans, directing the production of antigens of various infectious agents in their cells (DNA vaccination). The newest direction of genetic engineering is the creation of edible vaccines based on transgenic plants, such as tomatoes, carrots, potatoes, corn, lettuce, etc., producing immunogenic proteins of infectious agents. genetic engineering recombinant molecule

Concerns associated with conductinggenetic engineering experiments

Soon after the first successful experiments on obtaining rivers of DNA, a group of scientists led by P. Berg proposed limiting the conduct of a number of genetic engineering experiments. These concerns were based on the fact that the properties of organisms containing foreign genetic information are difficult to predict. They can acquire undesirable characteristics, disrupt the ecological balance, and lead to the emergence and spread of unusual diseases in humans, animals, and plants. In addition, it was noted that human intervention in the genetic apparatus of living organisms is immoral and can cause undesirable social and ethical consequences. In 1975, these problems were discussed at an international conference in Asilomar (USA). Its participants came to the conclusion that it was necessary to continue using genetic engineering methods, but subject to mandatory compliance with certain rules and recommendations. Subsequently, these rules, established in a number of countries, were significantly relaxed and reduced to techniques common in microbiological research, the creation of special protective devices that prevent the spread of biological agents in the environment, the use of safe vectors and recipient cells that do not reproduce in natural conditions.

Often, genetic engineering is understood only as working with DNA, and the terms “molecular cloning”, “DNA cloning”, “gene cloning” are used as synonyms for genetic engineering. However, all these concepts reflect the content of only individual genetic engineering operations and therefore are not equivalent to the term “genetic engineering”. In Russia, the term “genetic engineering” is widely used as a synonym for genetic engineering. However, the semantic content of these terms is different: genetic engineering aims to create organisms with a new genetic program, while the term “genetic engineering” explains how this is done - by manipulating genes.

Posted on Allbest.ru

Similar documents
Economic significance

Genetic engineering serves to obtain the desired qualities of a changeable or genetically modified organism. Unlike traditional selection, during which the genotype is subject to changes only indirectly, genetic engineering allows direct intervention in the genetic apparatus using the technique of molecular cloning. Examples of the application of genetic engineering are the production of new genetically modified varieties of grain crops, the production of human insulin using genetically modified bacteria, the production of erythropoietin in cell culture or new breeds of experimental mice for scientific research.

The basis of the microbiological, biosynthetic industry is the bacterial cell. The cells necessary for industrial production are selected according to certain characteristics, the most important of which is the ability to produce, synthesize, in the maximum possible quantities, a certain compound - an amino acid or an antibiotic, a steroid hormone or an organic acid. Sometimes you need to have a microorganism that can, for example, use oil or wastewater as “food” and process it into biomass or even protein quite suitable for feed additives. Sometimes we need organisms that can develop at elevated temperatures or in the presence of substances that are certainly lethal to other types of microorganisms.

The task of obtaining such industrial strains is very important; for their modification and selection, numerous methods of actively influencing the cell have been developed - from treatment with potent poisons to radioactive irradiation. The goal of these techniques is one - to achieve changes in the hereditary, genetic apparatus of the cell. Their result is the production of numerous mutant microbes, from hundreds and thousands of which scientists then try to select the most suitable for a particular purpose. The creation of methods of chemical or radiation mutagenesis was an outstanding achievement of biology and is widely used in modern biotechnology.

But their capabilities are limited by the nature of the microorganisms themselves. They are not able to synthesize a number of valuable substances that accumulate in plants, primarily in medicinal and essential oil plants. They cannot synthesize substances that are very important for the life of animals and humans, a number of enzymes, peptide hormones, immune proteins, interferons, and many simpler compounds that are synthesized in the bodies of animals and humans. Of course, the possibilities of microorganisms are far from exhausted. Of the entire abundance of microorganisms, only a tiny fraction has been used by science, and especially by industry. For the purpose of selection of microorganisms, of great interest are, for example, anaerobic bacteria capable of living in the absence of oxygen, phototrophs that use light energy like plants, chemoautotrophs, thermophilic bacteria capable of living at temperatures, as recently discovered, about 110 ° C, etc.

And yet the limitations of “natural material” are obvious. They have tried and are trying to get around the restrictions with the help of cell and tissue cultures of plants and animals. This is a very important and promising path, which is also being implemented in biotechnology. Over the past few decades, scientists have developed methods by which individual tissue cells of a plant or animal can be made to grow and reproduce separately from the body, like bacterial cells. This was an important achievement - the resulting cell cultures are used for experiments and for the industrial production of certain substances that cannot be obtained using bacterial cultures.

History of development and achieved level of technology

In the second half of the 20th century, several important discoveries and inventions were made that underlie genetic engineering. Many years of attempts to “read” the biological information that is “written” in genes have been successfully completed. This work was started by the English scientist F. Sanger and the American scientist W. Gilbert (Nobel Prize in Chemistry). As is known, genes contain information-instructions for the synthesis of RNA molecules and proteins, including enzymes, in the body. To force a cell to synthesize new substances that are unusual for it, it is necessary that the corresponding sets of enzymes be synthesized in it. And for this it is necessary to either purposefully change the genes located in it, or introduce new, previously absent genes into it. Changes in genes in living cells are mutations. They occur under the influence, for example, of mutagens - chemical poisons or radiation. But such changes cannot be controlled or directed. Therefore, scientists have focused their efforts on trying to develop methods for introducing new, very specific genes needed by humans into cells.

The main stages of solving a genetic engineering problem are as follows:
1. Obtaining an isolated gene. 2. Introduction of the gene into a vector for transfer into the body. 3. Transfer of the vector with the gene into the modified organism. 4. Transformation of body cells. 5. Selection of genetically modified organisms ( GMO) and eliminating those that were not successfully modified.
The process of gene synthesis is now very well developed and even largely automated. There are special devices equipped with computers, in the memory of which programs for the synthesis of various nucleotide sequences are stored. This apparatus synthesizes DNA segments up to 100-120 nitrogen bases in length (oligonucleotides). A technique has become widespread that makes it possible to use the polymerase chain reaction for the synthesis of DNA, including mutant DNA. A thermostable enzyme, DNA polymerase, is used in it for template DNA synthesis, for which artificially synthesized pieces of nucleic acid - oligonucleotides - are used as seeds. The enzyme reverse transcriptase allows, using such primers, to synthesize DNA on a template of RNA isolated from cells. The DNA synthesized in this way is called complementary DNA (RNA) or cDNA. An isolated, "chemically pure" gene can also be obtained from a phage library. This is the name of a bacteriophage preparation, into the genome of which random fragments from the genome or cDNA are built in, reproduced by the phage along with all its DNA.

The technique of introducing genes into bacteria was developed after Frederick Griffith discovered the phenomenon of bacterial transformation. This phenomenon is based on a primitive sexual process, which in bacteria is accompanied by the exchange of small fragments of non-chromosomal DNA, plasmids. Plasmid technologies formed the basis for the introduction of artificial genes into bacterial cells.

Significant difficulties were associated with the introduction of a ready-made gene into the hereditary apparatus of plant and animal cells. However, in nature there are cases when foreign DNA (of a virus or bacteriophage) is included in the genetic apparatus of a cell and, with the help of its metabolic mechanisms, begins to synthesize “its” protein. Scientists studied the features of the introduction of foreign DNA and used it as a principle for introducing genetic material into a cell. This process is called transfection.

If unicellular organisms or multicellular cell cultures are subject to modification, then at this stage cloning begins, that is, the selection of those organisms and their descendants (clones) that have undergone modification. When the task is to obtain multicellular organisms, cells with an altered genotype are used for vegetative propagation of plants or introduced into the blastocysts of a surrogate mother when it comes to animals. As a result, cubs are born with a changed or unchanged genotype, among which only those that exhibit the expected changes are selected and crossed with each other.

Application in scientific research

Although on a small scale, genetic engineering is already being used to give women with some types of infertility a chance to get pregnant. For this purpose, eggs from a healthy woman are used. As a result, the child inherits the genotype from one father and two mothers.

However, the possibility of making more significant changes to the human genome faces a number of serious ethical problems.

Genetic engineering is a method of biotechnology that deals with research into the restructuring of genotypes. The genotype is not just a mechanical sum of genes, but a complex system that has developed during the evolution of organisms. Genetic engineering makes it possible to transfer genetic information from one organism to another through in vitro operations. Gene transfer makes it possible to overcome interspecies barriers and transfer individual hereditary characteristics of one organism to another.

The carriers of the material basis of genes are chromosomes, which include DNA and proteins. But the genes of formation are not chemical, but functional. From a functional point of view, DNA consists of many blocks that store a certain amount of information - genes. The action of the gene is based on its ability to determine protein synthesis through RNA. The DNA molecule contains, as it were, information that determines the chemical structure of protein molecules. A gene is a section of a DNA molecule that contains information about the primary structure of any one protein (one gene - one protein). Because there are tens of thousands of proteins in organisms, there are tens of thousands of genes. The totality of all the genes of a cell makes up its genome. All cells of the body contain the same set of genes, but each of them implements a different part of the stored information. Therefore, for example, nerve cells differ from liver cells in both structural, functional and biological characteristics.

Rearrangement of genotypes, when performing genetic engineering tasks, represents qualitative changes in genes not associated with changes in the structure of chromosomes visible in a microscope. Gene changes primarily involve changes in the chemical structure of DNA. Information about the structure of a protein, written as a sequence of nucleotides, is implemented as a sequence of amino acids in the synthesized protein molecule. A change in the sequence of nucleotides in chromosomal DNA, the loss of some and the inclusion of other nucleotides, changes the composition of the RNA molecules formed on DNA, and this, in turn, determines a new sequence of amino acids during synthesis. As a result, a new protein begins to be synthesized in the cell, which leads to the appearance of new properties in the body. The essence of genetic engineering methods is that individual genes or groups of genes are inserted into or excluded from the genotype of an organism. As a result of inserting a previously absent gene into the genotype, the cell can be forced to synthesize proteins that it had not previously synthesized.

The most common method of genetic engineering is the method of obtaining recombinant, i.e. containing a foreign gene, plasmid. Plasmids are circular double-stranded DNA molecules consisting of several thousand nucleotide pairs. This process consists of several stages.

1. Restriction - cutting DNA, for example, of a person, into fragments.

2. Ligation - a fragment with the desired gene is included in plasmids and stitched together.

3. Transformation - introduction of recombinant plasmids into bacterial cells. The transformed bacteria acquire certain properties. Each of the transformed bacteria multiplies and forms a colony of many thousands of descendants - a clone.

4. Screening - selection among clones of transformed bacteria of those with plasmids carrying the desired human gene.

This entire process is called cloning. Using cloning, it is possible to obtain more than a million copies of any fragment of DNA from a person or other organism. If the cloned fragment encodes a protein, then it is possible to experimentally study the mechanism that regulates the transcription of this gene, as well as produce this protein in the required quantity. In addition, a cloned DNA fragment from one organism can be introduced into the cells of another organism. This can achieve, for example, high and stable yields thanks to the introduced gene that provides resistance to a number of diseases. If you introduce into the genotype of soil bacteria the genes of other bacteria that have the ability to fix atmospheric nitrogen, then the soil bacteria will be able to convert this nitrogen into fixed soil nitrogen. By introducing into the genotype of the E. coli bacterium a gene from the human genotype that controls the synthesis of insulin, scientists achieved the production of insulin through such E. coli. With the further development of science, it will become possible to introduce missing genes into the human embryo, and thereby avoid genetic diseases.

Animal cloning experiments have been going on for a long time. It is enough to remove the nucleus from the egg, implant into it the nucleus of another cell taken from embryonic tissue, and grow it - either in a test tube or in the womb of an adoptive mother. The cloned sheep Doli was created in an unconventional way. A nucleus from the udder cell of a 6-year-old adult sheep of one breed was transplanted into a nuclear-free egg of a sheep of another breed. The developing embryo was placed in a sheep of the third breed. Since the newborn lamb received all the genes from the first donor sheep, it is its exact genetic copy. This experiment opens up a lot of new opportunities for cloning elite breeds, instead of many years of selection.

Scientists at the University of Texas have been able to extend the life of several types of human cells. Usually a cell dies after going through about 7-10 division processes, but they achieved a hundred cell divisions. Aging, according to scientists, occurs because cells lose telomeres, the molecular structures that are located at the ends of all chromosomes, with each division. Scientists implanted the gene they discovered, which is responsible for the production of telomerase, into the cells and thereby made them immortal. Perhaps this is the future path to immortality.

Since the 80s, programs to study the human genome have appeared. In the process of executing these programs, about 5 thousand genes have already been read (the complete human genome contains 50-100 thousand). A number of new human genes have been discovered. Genetic engineering is becoming increasingly important in gene therapy. Because many diseases are determined at the genetic level. It is in the genome that there is a predisposition to or resistance to many diseases. Many scientists believe that genomic medicine and genetic engineering will function in the 21st century.

Genetic engineering short message. Genetic engineering

Encyclopedic YouTube

History of development and achieved level of technology

Application in scientific research

Cell engineering

Genetic engineering in Russia

see also

Notes

Send your good work in the knowledge base is simple. Use the form below

Similar documents

Economic significance

History of development and achieved level of technology

Application in scientific research