The most important events in the field of biology that influenced the entire course of its further development are: the establishment of the molecular structure of DNA and its role in the transmission of information in living matter (F. Crick, J. Watson, M. Wilkins); decoding genetic code(R. Holly, H.-G. Koran, M. Nirenberg); the discovery of the structure of the gene and the genetic regulation of protein synthesis (A. M. Lvov, F. Jacob, J.-L. Monod, and others); formulation of the cell theory (M. Schleiden, T. Schwann, R. Virchow, K. Baer); study of the laws of heredity and variability (G. Mendel, G. de Vries, T. Morgan, etc.); formulation of the principles of modern systematics (C. Linnaeus), evolutionary theory (C. Darwin) and the doctrine of the biosphere (V.I. Vernadsky).
The significance of the discoveries of the last decades has yet to be assessed, however, the most important achievements of biology have been recognized as: deciphering the genome of humans and other organisms, determining the mechanisms for controlling the flow of genetic information in the cell and the developing organism, the mechanisms for regulating cell division and death, cloning of mammals, as well as the discovery of pathogens " mad cow disease (prions).
The work on the "Human Genome" program, which was carried out simultaneously in several countries and was completed at the beginning of this century, led us to understand that a person has only about 25-30 thousand genes, but information from most of our DNA is not readable never, since it contains a huge number of sites and genes that encode traits that have lost their meaning for humans (tail, body hair, etc.). In addition, a number of genes responsible for the development of hereditary diseases, as well as target genes, have been deciphered. medicines. However practical use the results obtained during the implementation of this program are postponed until the genomes of a significant number of people are decoded, and then it becomes clear what is their difference. These goals are set for a number of leading laboratories around the world working on the implementation of the ENCODE program.
Biological research is the foundation of medicine, pharmacy, widely used in agriculture and forestry, Food Industry and other branches of human activity.
It is well known that only the "green revolution" of the 1950s made it possible to at least partially solve the problem of providing the rapidly growing population of the Earth with food, and animal husbandry with feed through the introduction of new plant varieties and advanced technologies for their cultivation. Due to the fact that the genetically programmed properties of agricultural crops have almost been exhausted, the further solution of the food problem is associated with the widespread introduction of genetically modified organisms into production.
The production of many food products, such as cheeses, yogurts, sausages, bakery products, etc., is also impossible without the use of bacteria and fungi, which is the subject of biotechnology.
Knowledge of the nature of pathogens, the processes of the course of many diseases, the mechanisms of immunity, the laws of heredity and variability made it possible to significantly reduce mortality and even completely eradicate a number of diseases, such as smallpox. With the help of the latest achievements of biological science, the problem of human reproduction is also being solved. A significant part of modern medicines is produced on the basis of natural raw materials, as well as thanks to the success of genetic engineering, such as insulin, which is so necessary for patients with diabetes mellitus, which is mainly synthesized by bacteria that have transferred the corresponding gene.
No less important biological research to save environment and diversity of living organisms, the threat of extinction of which calls into question the existence of mankind.
The greatest importance among the achievements of biology is the fact that they even underlie the construction of neural networks and the genetic code in computer technology, and are also widely used in architecture and other industries. Without a doubt, the 21st century is the century of biology.
Section 1. Biology is the science of life.
Plan
Topic 1. Biology as a science, its achievements, research methods, connections with other sciences. The role of biology in the life and practical activities of man.
Topic 2. Signs and properties of living things: cellular structure, chemical composition, metabolism and energy conversion, homeostasis, irritability, reproduction, development
Topic 3. The main levels of organization of wildlife: cellular, organismal, population-species, biogeocenotic
Biology as a science, its achievements, methods of cognition of living nature. The role of biology in the formation of the modern natural-science picture of the world.
Biology as a science.
Biology(from Greek. bios- life, logos- word, science) is a complex of sciences about wildlife.
The subject of biology is all manifestations of life: the structure and functions of living beings, their diversity, origin and development, as well as interaction with the environment. The main task of biology as a science is to interpret all the phenomena of living nature on a scientific basis, while taking into account that the whole organism has properties that are fundamentally different from its components.
The term "biology" is found in the works of the German anatomists T. Roose (1779) and K.-F. Burdakh (1800), but it was not until 1802 that it was first used independently by J.-B. Lamarck and G.-R. Treviranus to refer to the science that studies living organisms.
Biological Sciences.
Currently, biology includes a number of sciences that can be systematized according to the following criteria: subject and predominant methods research and study the level of organization of wildlife. According to the subject of study, biological sciences are divided into bacteriology, botany, virology, zoology, mycology.
Botany is a biological science that comprehensively studies plants and the vegetation cover of the Earth. Zoology- a branch of biology, the science of diversity, structure, life, distribution and relationship of animals with the environment, their origin and development. Bacteriology- biological science that studies the structure and vital activity of bacteria, as well as their role in nature. Virology is the biological science that studies viruses. main object mycology are mushrooms, their structure and features of vital activity. Lichenology- biological science that studies lichens. Bacteriology, virology and some aspects of mycology are often considered within microbiology- section of biology, the science of microorganisms (bacteria, viruses and microscopic fungi). Systematics, or taxonomy,- biological science that describes and classifies into groups all living and extinct creatures.
In turn, each of the listed biological sciences is subdivided into biochemistry, morphology, anatomy, physiology, embryology, genetics and taxonomy (of plants, animals or microorganisms). Biochemistry- this is the science of the chemical composition of living matter, chemical processes occurring in living organisms and underlying their vital activity. Morphology- biological science that studies the shape and structure of organisms, as well as the patterns of their development. In a broad sense, it includes cytology, anatomy, histology and embryology. Distinguish the morphology of animals and plants. Anatomy- This is a branch of biology (more precisely, morphology), a science that studies the internal structure and shape of individual organs, systems and the body as a whole. Plant anatomy is considered as part of botany, animal anatomy is considered as part of zoology, and human anatomy is a separate science. physiology- biological science that studies the processes of vital activity of plant and animal organisms, their individual systems, organs, tissues and cells. There are physiology of plants, animals and humans. Embryology (developmental biology)- a branch of biology, the science of the individual development of the organism, including the development of the embryo.
object genetics are patterns of heredity and variability. Currently, it is one of the most dynamically developing biological sciences.
According to the level of organization of living nature studied, molecular biology, cytology, histology, organology, biology of organisms and supraorganismal systems are distinguished. Molecular biology is one of the youngest sections of biology, a science that studies, in particular, the organization of hereditary information and protein biosynthesis. Cytology, or cell Biology,- biological science, the object of study of which are the cells of both unicellular and multicellular organisms. Histology- biological science, a section of morphology, the object of which is the structure of tissues of plants and animals. To the sphere organology include the morphology, anatomy and physiology of various organs and their systems.
Biology of organisms includes all sciences that deal with living organisms, for example, ethology the science of the behavior of organisms.
The biology of supraorganismal systems is subdivided into biogeography and ecology. The distribution of living organisms studies biogeography, whereas ecology- organization and functioning of supraorganismal systems at various levels: populations, biocenoses (communities), biogeocenoses (ecosystems) and the biosphere.
According to the prevailing research methods, one can single out descriptive (for example, morphology), experimental (for example, physiology) and theoretical biology.
Revealing and explaining the regularities of the structure, functioning and development of living nature at various levels of its organization is a task general biology. It includes biochemistry, molecular biology, cytology, embryology, genetics, ecology, evolutionary science and anthropology. evolutionary doctrine studies the reasons driving forces, mechanisms and general patterns evolution of living organisms. One of its sections is paleontology- science, the subject of which are the fossil remains of living organisms. Anthropology- a section of general biology, the science of the origin and development of man as a biological species, as well as the diversity of populations of modern man and the patterns of their interaction.
Applied aspects of biology are assigned to the field of biotechnology, breeding and other rapidly developing sciences. Biotechnology called the biological science that studies the use of living organisms and biological processes in production. It is widely used in food (baking, cheese-making, brewing, etc.) and pharmaceutical industries (obtaining antibiotics, vitamins), for water purification, etc. Selection- the science of methods for creating breeds of domestic animals, varieties of cultivated plants and strains of microorganisms with the properties necessary for a person. Selection is also understood as the process of changing living organisms, carried out by man for his needs.
The progress of biology is closely related to the progress of other natural and exact sciences such as physics, chemistry, mathematics, computer science, etc. For example, microscopy, ultrasound research (ultrasound), tomography and other methods of biology are based on physical laws, and the study of the structure of biological molecules and processes occurring in living systems would be impossible without application of chemical and physical methods. The use of mathematical methods allows, on the one hand, to identify the presence of a regular connection between objects or phenomena, to confirm the reliability of the results obtained, and on the other hand, to model a phenomenon or process. IN Lately computer methods, such as modeling, are becoming increasingly important in biology. At the intersection of biology and other sciences, a number of new sciences have arisen, such as biophysics, biochemistry, bionics, etc.
Lecture:
Biology as a science
Biology became a separate science in the 19th century, when several scientists began to use the term "biology" at once - Jean Baptiste Lamarck and Gottfried Reinhold Treviranus in 1802 and Friedrich Burdach in 1800. Before that, natural history and medicine were engaged in the study of some aspects of the living.
The object of study of biology is life in all its manifestations - evolution, distribution of life on the planet, its structure, functioning processes, classification, relationships of organisms with each other and with the environment.
basis modern biology are 5 basic principles:
cell theory;
genetics;
evolution;
homeostasis;
biology methods
Biology methods called the techniques used by scientists to acquire new knowledge about living organisms.
The basic rule for any scientist is the principle of "taking nothing for granted" - each phenomenon must be accurately studied and reliable knowledge must be obtained about it.
The methods of biology are the methods by which a system of exact scientific knowledge is built. These include:
observation. The first collision of scientists with something not yet studied.
Description phenomena, a new organism, its features;
Systematization. This is the process of correlating new knowledge with existing systems - determining the place of a newly discovered organism on the tree of evolution, its chemical structure, features of reproduction and other properties with existing systems of knowledge;
Comparison. Search for similar phenomena, the study of already encountered similar evidence from other scientists, descriptions and unfinished studies;
Experiment. Conducting a series of experiments to confirm or refute a new theory or hypothesis.
Analytical method. It implies the collection and comparison of all information on any issue.
historical method. Allows you to study patterns historical development organisms, referring to existing knowledge.
Modeling. Construction and calculation options the structure of the body, the functioning of its organs, its interaction with other living organisms. These can be computer models, three-dimensional models of the structure, a mathematical method.
Universal, common to all sciences are usedrules for constructing scientific theories:
observation any phenomenon, properties of a living organism, its features;
hypothesizing – how and why the observed phenomenon is possible, its preliminary explanation on the basis of previously known knowledge;
experiment- whether the phenomenon is constant or has a random character, whether it manifests itself in the same way when the conditions of the experiment change, what specific conditions affect it;
after experimental confirmation hypothesis becomes theory ;
to test the theory and search for exact answers to questions, scientists conduct additional experiments.
And also the methods inherent in each particular science are applied, for biology it is:
genealogical . Search for ancestors, correlation of a newly discovered organism with possible relatives on the tree of evolution;
tissue culture. For studying physiological characteristics organism, the influence of various factors on it, studies of samples of its tissues are carried out;
embryological. The study of the development process of a living organism before its birth;
cytogenetic. Studies of the genome and cell structure;
biochemical. Chemical studies of cellular contents, tissues, internal environment and excretions of the body.
There are a lot of biological methods, in addition to those listed above, in science are widely used: hybridization, paleontological, centrifugation and many others.
The role of biology in the formation of the natural-science picture of the world
Knowledge about the biosphere helps mankind to make forecasts of long-term and short-term processes on Earth and try to manage them. Thus, knowing about the role of green plants in shaping the planet's oxygen environment, a person understands the importance of forest conservation. Possessing knowledge about the relationships between organisms, at present, humanity no longer allows dangerous experiments to introduce new animals and plants into a stable ecosystem, this is even spelled out in international law. Mistakes such as bringing rabbits into Australia or a raccoon dog into Far East The USSR no longer allows people. Currently, alien plant species have become a problem in California, oppressing relict valuable species of local flora.
Biological sciences allow solving many problems with providing food security. Breeding new varieties of plants and animal species can increase productivity, protect crops from pests, and increase agricultural productivity.
GeneticsAndphysiology on currently play a very important role in obtaining medical knowledge, contributing to the development of new methods of treatment, the creation of drugs, allowing to defeat diseases and pathologies that were considered incurable, as well as to prevent and stop their development in advance.
By using microbiology vaccines and sera, new varieties of foods and drinks are being developed.
Dendrology and ecology allow to provide replenished natural resource- timber construction and pulp and paper industries.
Entomology and botany – help to develop and improve already known types of fabrics.
Any of the biological sciences, including paleontology and others that seem unimportant, has strong influence on the presentation of knowledge about the history of the development of the planet, the place of man among living organisms, helps to improve the quality of life and protect against the influence of harmful environmental factors.
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The most significant events of the first half of XIX century began the formation of paleontology and the biological foundations of stratigraphy, the emergence of cell theory, the formation of comparative anatomy and comparative embryology. The central events of the second half of the 19th century were the publication of Charles Darwin's On the Origin of Species and the spread of the evolutionary approach to many biological disciplines.
cell theory
The cell theory was formulated in 1839. German zoologist and physiologist T. Schwann. According to this theory, all organisms have cellular structure. The cell theory asserted the unity of the animal and flora, the presence of a single element of the body of a living organism - cells. Like any major scientific generalization, the cell theory did not emerge suddenly: it was preceded by separate discoveries by various researchers.
IN early XIX V. attempts were made to study the internal contents of the cell. In 1825 Czech scientist J. Purkyne discovered the nucleus in the egg of birds. In 1831 the English botanist R. Brown first described the nucleus in plant cells, and in 1833. he came to the conclusion that the nucleus is an essential part of the plant cell. Thus, at this time, the idea of the structure of the cell changes: the main thing in its organization was considered not the cell wall, but the contents.
The German botanist M. Schleiden came closest to the formulation of the cell theory, who established that the body of plants consists of cells.
Numerous observations regarding the structure of the cell, the generalization of the accumulated data allowed T. Schwann in 1839 to draw a number of conclusions, which were later called the cell theory. The scientist showed that all living organisms consist of cells, that the cells of plants and animals are fundamentally similar to each other.
Cell theory includes the following main provisions:
1) A cell is an elementary unit of a living being capable of self-renewal, self-regulation and self-reproduction and is a unit of structure, functioning and development of all living organisms.
2) The cells of all living organisms are similar in structure, chemical composition and the main manifestations of life.
3) Reproduction of cells occurs by dividing the original mother cell.
4) In a multicellular organism, cells specialize in functions and form tissues from which organs and their systems are built, interconnected by intercellular, humoral and nervous forms of regulation.
The creation of cell theory has become major event in biology, one of the decisive proofs of the unity of living nature. The cell theory had a significant impact on the development of biology as a science, served as the foundation for the development of such disciplines as embryology, histology and physiology. It made it possible to create the foundations for understanding life, individual development organisms to explain the evolutionary relationship between them. The main provisions of the cell theory have retained their significance even today, although for more than one hundred and fifty years new information has been obtained on the structure, vital activity and development of the cell.
The evolutionary theory of Ch. Darwin
A revolution in science was made by the book of the great English natural scientist Charles Darwin, "The Origin of Species", written in 1859. Summarizing the empirical material of contemporary biology and breeding practice, using the results of his own observations during his travels, he revealed the main factors in the evolution of the organic world. In the book "Changing Domestic Animals and Cultivated Plants" (1868), he presented additional factual material to the main work. In the book "The Origin of Man and Sexual Selection" (1871), he put forward the hypothesis of the origin of man from an ape-like ancestor.
The essence of the Darwinian concept of evolution is reduced to a number of logical, experimentally verified and confirmed by a huge amount of factual data provisions:
1) Within each species of living organisms, there is a huge range of individual hereditary variability in morphological, physiological, behavioral and any other characteristics. This variability may be continuous, quantitative, or discontinuous qualitative, but it always exists.
2) All living organisms reproduce exponentially.
3) Life resources for any kind of living organisms are limited, and therefore there must be a struggle for existence either between individuals of the same species, or between individuals different types, or with natural conditions. In the concept of "struggle for existence" Darwin included not only the actual struggle of an individual for life, but also the struggle for success in reproduction.
4) In the conditions of the struggle for existence, the most adapted individuals survive and give offspring, having those deviations that accidentally turned out to be adaptive to given environmental conditions. This is a fundamentally important point in Darwin's argument. Deviations do not occur in a directed way - in response to the action of the environment, but by chance. Few of them are useful in specific conditions. The descendants of a surviving individual who inherit a beneficial variation that allowed their ancestor to survive are better adapted to the environment than other members of the population.
5) Survival and preferential reproduction of adapted individuals Darwin called natural selection.
6) The natural selection of individual isolated varieties under different conditions of existence gradually leads to divergence (divergence) of the characteristics of these varieties and, ultimately, to speciation.
At the heart of Darwin's theory is the property of organisms to repeat in a number of generations similar types of metabolism and individual development in general - the property of heredity. Heredity, together with variability, ensures the constancy and diversity of life forms and underlies the evolution of living nature. One of the basic concepts of his theory of evolution - the concept of "struggle for existence" - Darwin used to denote the relationship between organisms, as well as the relationship between organisms and abiotic conditions, leading to the death of the less adapted and the survival of the more adapted individuals.
Darwin identified two main forms of variability:
A certain variability - the ability of all individuals of the same species in certain environmental conditions to respond in the same way to these conditions (climate, soil);
Uncertain variability, the nature of which does not correspond to changes in external conditions.
In modern terminology, indefinite variability is called a mutation. Mutation - indefinite variability, in contrast to a certain one, is hereditary. According to Darwin, minor changes in the first generation are amplified in subsequent ones. Darwin emphasized that it is precisely indefinite variability that plays a decisive role in evolution. It is usually associated with deleterious and neutral mutations, but mutations that turn out to be promising are also possible. The inevitable result of the struggle for existence and the hereditary variability of organisms, according to Darwin, is the process of survival and reproduction of organisms that are most adapted to environmental conditions, and death in the course of evolution of the unadapted - natural selection.
The mechanism of natural selection in nature operates similarly to breeders, i.e. adds up minor and indefinite individual differences and forms from them the necessary adaptations in organisms, as well as interspecies differences. This mechanism discards unnecessary forms and forms new species. Darwinism: history and modernity. M., Science, 1985
Thesis about natural selection along with the principles of the struggle for existence, heredity and variability - the basis of the Darwinian theory of evolution.
Cell theory and Darwin's theory of evolution are the most significant achievements of biology in the 19th century. But I think that other rather important discoveries should also be mentioned.
With the development of physics and chemistry, there are also changes in medicine. Over time, the areas of application of electricity are becoming more and more. Its use in medicine marked the beginning of electro- and iontophoresis. The discovery of X-rays by Roentgen aroused particular interest among physicians. The physics laboratories where the equipment used by Roentgen to produce X-rays were created were attacked by doctors and their patients, who suspected that they contained needles, buttons, etc., once swallowed. The history of medicine did not know such a rapid implementation of discoveries in the field of electricity before, as happened with a new diagnostic tool - x-rays.
WITH late XIX century, experiments on animals begin to determine the threshold - dangerous - values of current and voltage. The determination of these values was caused by the need to create protective measures.
Quite a few important discovery in the field of medicine and biology was the discovery of vitamins. Back in 1820, our compatriot P. Vishnevsky for the first time suggested the existence of a certain substance in antiscorbutic products that contributes to the proper functioning of the body. Actually, the discovery of vitamins belongs to N. Lunin, who proved in 1880 that certain vital elements are included in the composition of food. The term "vitamins" is derived from the Latin roots: "vita" - life and "amine" - a nitrogen compound.
In the 19th century, the fight against infectious diseases began. The English doctor Jenner invented the vaccine, Robert Koch discovered the causative agent of tuberculosis - Koch's bacillus, and also developed preventive measures against epidemics and created medicines.
Microbiology
Louis Pasteur gave the world new science- microbiology.
This man, who made a number of the brightest discoveries, had to defend his truths in useless disputes all his life. Natural scientists all over the world have been debating whether or not there is a "self-generation" of living organisms. Pasteur did not argue, Pasteur worked. Why does wine ferment? Why does milk sour? Pasteur established that the process of fermentation is a biological process caused by microbes.
In Pasteur's laboratory, there is still an amazingly shaped flask - a fragile structure with a bizarrely curved spout. More than 100 years ago, young wine was poured into it. It has not turned sour to this day - the secret of the form protects it from fermentation microbes.
Pasteur's experiments were great importance to create sterilization and pasteurization methods (heating a liquid to 80°C to kill microorganisms and then rapidly cooling it) of various products. He developed methods of protective vaccinations against contagious diseases. His research served as the basis for the teachings on immunity.
Genetics
In 1865, the results of work on the hybridization of pea varieties were published, where the most important laws of heredity were discovered. The author of these works, the Czech researcher Gregor Mendel, showed that the characteristics of organisms are determined by discrete hereditary factors. However, these works remained practically unknown for almost 35 years - from 1865 to 1900.
- 33.35 KbAchievements in biology modern versions systematics of life
Based on the latest scientific achievements Modern biological science gives the following definition of life: “Life is open self-regulating and self-reproducing systems of living organisms, built from complex biological polymers - proteins and nucleic acids” (I. I. Mechnikov).
Recent advances in biology have led to the emergence of fundamentally new directions in science. The discovery of the molecular structure of the structural units of heredity (genes) served as the basis for the creation of genetic engineering. With the help of its methods, organisms are created with new, including those not found in nature, combinations of hereditary traits and properties. It opens up opportunities for breeding new varieties of cultivated plants and highly productive animal breeds, creating effective drugs, etc.
Living nature arranged itself brilliantly simply and wisely. It has the only self-reproducing DNA molecule on which the life program is written, and more specifically, the entire synthesis process, the structure and function of proteins as the basic elements of life. In addition to preserving the life program, the DNA molecule performs another important function - its self-reproduction, copying create continuity between generations, the continuity of the thread of life. Once having arisen, life reproduces itself in a huge variety, which ensures its stability, adaptability to various environmental conditions and evolution.
Modern biotechnologies
Modern biology is an area of rapid and fantastic transformations in biotechnology.
Biotechnologies are based on the use of living organisms and biological processes in industrial production. On their basis, mass production of artificial proteins, nutrients and many other substances, superior to products of natural origin in many properties, has been mastered. The microbiological synthesis of enzymes, vitamins, amino acids, antibiotics, etc. is successfully developing. With the use of gene technologies and natural bioorganic materials, biologically active substances are synthesized - hormonal preparations and compounds that stimulate the immune system.
Modern biotechnology makes it possible to turn waste wood, straw and other plant materials into valuable nutritious proteins. It includes the process of hydrolysis of the intermediate product - cellulose - and the neutralization of the resulting glucose with the introduction of salts. The resulting glucose solution is a nutrient substrate for microorganisms - yeast fungi. As a result of the vital activity of microorganisms, a light brown powder is formed - a high-quality food product containing about 50% of raw protein and various vitamins. Sugar-containing solutions such as treacle stillage and sulfite liquor from pulp production can also serve as a nutrient medium for yeasts.
Some types of fungi convert oil, fuel oil and natural gas into protein-rich edible biomass. Thus, 10 tons of yeast biomass containing 5 tons of pure protein and 90 tons of diesel fuel can be obtained from 100 tons of crude fuel oil. The same amount of yeast is produced from 50 tons of dry wood or 30 thousand m3 of natural gas. To produce this amount of protein would require a herd of 10,000 cows, and to maintain them, huge areas of arable land are needed. industrial production proteins is fully automated, and yeast cultures grow thousands of times faster than cattle. One ton of nutritional yeast allows you to get about 800 kg of pork, 1.5-2.5 tons of poultry or 15-30 thousand eggs and save up to 5 tons of grain.
The practical application of the achievements of modern biology already at the present time makes it possible to obtain industrially significant amounts of biologically active substances.
Biotechnology, apparently, will take a leading position in the coming decades and, perhaps, will determine the face of civilization in the 21st century.
Gene technologies
Genetics is the most important area of modern biology.
On the basis of genetic engineering, modern biotechnology was born. There are now a huge number of firms doing business in this area in the world. They do everything from drugs, antibodies, hormones, food proteins to technical things - ultra-sensitive sensors (biosensors), computer microcircuits, chitin cones for good acoustic systems. Genetically engineered products are conquering the world, they are environmentally safe.
At the initial stage of the development of gene technologies, a number of biologically active compounds were obtained - insulin, interferon, etc. Modern gene technologies combine the chemistry of nucleic acids and proteins, microbiology, genetics, biochemistry and open up new ways to solve many problems in biotechnology, medicine and agriculture.
Gene technologies are based on the methods of molecular biology and genetics associated with the purposeful construction of new combinations of genes that do not exist in nature. The main operation of gene technology is to extract from the cells of an organism a gene encoding the desired product, or a group of genes, and combine them with DNA molecules that can multiply in the cells of another organism.
The DNA stored and working in the cell nucleus reproduces more than just itself. At the right moment, certain sections of DNA - genes - reproduce their copies in the form of a chemically similar polymer - RNA, ribonucleic acid, which in turn serve as templates for the production of many proteins necessary for the body. It is proteins that determine all the signs of living organisms. The main chain of events at the molecular level:
DNA -> RNA -> protein
This line contains the so-called central dogma of molecular biology.
Gene technologies have led to the development of modern methods for the analysis of genes and genomes, and they, in turn, to synthesis, i.e. to the construction of new, genetically modified microorganisms. To date, the nucleotide sequences of various microorganisms, including industrial strains, have been established, and those that are needed to study the principles of genome organization and to understand the mechanisms of microbial evolution. Industrial microbiologists, in turn, are convinced that knowledge of the nucleotide sequences of the genomes of industrial strains will allow them to be "programmed" so that they bring in a lot of income.
Cloning of eukaryotic (nuclear) genes in microbes is the fundamental method that led to the rapid development of microbiology. Fragments of the genomes of animals and plants are cloned in microorganisms for their analysis. To do this, artificially created plasmids are used as molecular vectors, gene carriers, as well as many other molecular entities for isolation and cloning.
With the help of molecular samples (DNA fragments with a certain sequence of nucleotides) it is possible to determine, say, whether donated blood is infected with the AIDS virus. And genetic technologies for identifying some microbes make it possible to monitor their spread, for example, inside a hospital or during epidemics.
Gene technologies for the production of vaccines are developing in two main directions. The first is the improvement of already existing vaccines and the creation of a combined vaccine, i.e. consisting of several vaccines. The second direction is obtaining vaccines against diseases: AIDS, malaria, stomach ulcers, etc.
Behind last years Gene technologies have significantly improved the efficiency of traditional producer strains. For example, in a fungal strain producing the antibiotic cephalosporin, the number of genes encoding expandase, the activity that determines the rate of cephalosporin synthesis, has been increased. As a result, antibiotic production increased by 15-40%.
Purposeful work is being carried out to genetically modify the properties of microbes used in the production of bread, cheese making, the dairy industry, brewing and winemaking in order to increase the resistance of production strains, increase their competitiveness in relation to harmful bacteria and improve the quality of the final product.
Genetically modified microbes are beneficial in the fight against harmful viruses and germs and insects. For example:
Plant resistance to herbicides, which is important for controlling weeds that clog fields and reduce the yield of cultivated plants. Herbicide-resistant varieties of cotton, corn, rapeseed, soybean, sugar beet, wheat and other plants have been obtained and are being used.
Plant resistance to insect pests. Development of the delta-endotoxin protein produced by different strains of the bacterium Bacillus turingensis. This protein is toxic to many insect species and is safe for mammals, including humans.
Plant resistance to viral diseases. To do this, genes that block the reproduction of viral particles in plants, such as interferon, nucleases, are introduced into the plant cell genome. Transgenic plants of tobacco, tomatoes and alfalfa with the beta-interferon gene have been obtained.
In addition to genes in the cells of living organisms, there are also independent genes in nature. They are called viruses if they can cause an infection. It turned out that the virus is nothing more than genetic material packed in a protein shell. The shell is a purely mechanical device, like a syringe, in order to package and then inject genes, and only genes, into the host cell and fall off. Then the viral genes in the cell begin to reproduce their RNA and their proteins on themselves. All this overwhelms the cell, it bursts, dies, and the virus in thousands of copies is released and infects other cells.
Illness, and sometimes even death, is caused by foreign, viral proteins. If the virus is "good", the person does not die, but can be ill all his life. A classic example is herpes, the virus of which is present in the body of 90% of people. This is the most adaptable virus, usually infecting a person in childhood and living in it all the time.
Thus, viruses are, in essence, biological weapons invented by evolution: a syringe filled with genetic material.
Now the example is already from modern biotechnology, an example of the operation with the germ cells of higher animals for the sake of noble goals. Humanity is experiencing difficulties with interferon, an important protein with anti-cancer and antiviral activity. Interferon is produced by an animal organism, including a human one. Alien, not human, interferon cannot be taken for the treatment of people, it is rejected by the body or is ineffective. A person produces too little interferon to be isolated for pharmacological purposes. Therefore, the following was done. The human interferon gene was introduced into a bacterium, which then multiplied and large quantities produced human interferon in accordance with the human gene sitting in it. Now this already standard technique is used all over the world. In the same way, and for quite some time now, genetically engineered insulin has been produced. With bacteria, however, there are many difficulties in purifying the desired protein from bacterial impurities. Therefore, they begin to abandon them, developing methods for introducing the necessary genes into higher organisms. It's more difficult, but it provides tremendous benefits. Now, in particular, dairy production of the necessary proteins using pigs and goats is already widespread. The principle here, very briefly and simplified, is this. Egg cells are extracted from the animal and inserted into their genetic apparatus, under the control of animal milk protein genes, foreign genes that determine the production of the necessary proteins: interferon, or antibodies necessary for a person, or special food proteins. The eggs are then fertilized and returned to the body. Part of the offspring begins to produce milk containing the necessary protein, and it is already quite simple to isolate it from milk. It turns out much cheaper, safer and cleaner.
In the same way, cows were bred to give "women's" milk (cow's milk with the necessary human proteins), suitable for artificial feeding of human babies. And now this is a rather serious problem.
In general, we can say that in practical terms, humanity has reached a rather dangerous milestone. We learned how to influence the genetic apparatus, including higher organisms. We learned how to direct, selective gene influence, the production of so-called transgenic organisms - organisms that carry any foreign genes. DNA is a substance that can be manipulated. In the last two or three decades, methods have emerged that can cut DNA into right places and glue with any other piece of DNA. Moreover, they can cut and paste not only certain ready-made genes, but also recombinants - combinations of different, including artificially created genes. This direction is called genetic engineering. Man has become a genetic engineer. In his hands, in the hands of a not so intellectually perfect being, there appeared boundless, gigantic possibilities - like the Lord God.
Modern cytology
New methods, especially electron microscopy, the use of radioactive isotopes, and high-speed centrifugation, are making great progress in studying the structure of the cell. In developing a unified concept of the physicochemical aspects of life, cytology is increasingly moving closer to other biological disciplines. At the same time, her classical methods based on fixation, staining and microscopic examination of cells still retain their practical value.
Cytological methods are used, in particular, in plant breeding to determine the chromosomal composition of plant cells. Such studies are of great help in planning experimental crossings and evaluating the results obtained. A similar cytological analysis is carried out on human cells: it allows you to identify some hereditary diseases associated with changes in the number and shape of chromosomes. Such an analysis, in combination with biochemical tests, is used, for example, in amniocentesis to diagnose hereditary defects in the fetus.
However, the most important application of cytological methods in medicine is the diagnosis of malignant neoplasms. In cancer cells, especially in their nuclei, specific changes occur. Malignant formations are nothing more than deviations in the normal development process due to the exit from the control of the systems that control development, primarily genetic ones. Cytology is a fairly simple and highly informative method for screening diagnostics of various manifestations of papillomavirus. This study is conducted in both men and women.
Description of work
Based on the latest scientific achievements of modern biological science, the following definition of life is given: “Life is open self-regulating and self-reproducing systems of living organisms, built from complex biological polymers - proteins and nucleic acids” (I. I. Mechnikov).
Recent advances in biology have led to the emergence of fundamentally new directions in science. The discovery of the molecular structure of the structural units of heredity (genes) served as the basis for the creation of genetic engineering. With the help of its methods, organisms are created with new, including those not found in nature, combinations of hereditary traits and properties. It opens up opportunities for breeding new varieties of cultivated plants and highly productive animal breeds, creating effective drugs, etc.
