There are such levels of organization of living matter - levels of biological organization: molecular, cellular, tissue, organ, organism, population-species and ecosystem.

Molecular level of organization- this is the level of functioning of biological macromolecules - biopolymers: nucleic acids, proteins, polysaccharides, lipids, steroids. From this level, the most important life processes begin: metabolism, energy conversion, transfer hereditary information. This level is studied: biochemistry, molecular genetics, molecular biology, genetics, biophysics.

Cellular level- this is the level of cells (cells of bacteria, cyanobacteria, unicellular animals and algae, unicellular fungi, cells of multicellular organisms). A cell is a structural unit of the living, a functional unit, a unit of development. This level is studied by cytology, cytochemistry, cytogenetics, microbiology.

Tissue level of organization- This is the level at which the structure and functioning of tissues is studied. This level is studied by histology and histochemistry.

Organ level of organization- This is the level of organs of multicellular organisms. Anatomy, physiology, embryology study this level.

Organismal level of organization- this is the level of unicellular, colonial and multicellular organisms. The specificity of the organismic level is that at this level the decoding and implementation of genetic information takes place, the formation of features inherent in individuals of a given species. This level is studied by morphology (anatomy and embryology), physiology, genetics, paleontology.

Population-species level is the level of populations of individuals - populations And species. This level is studied by systematics, taxonomy, ecology, biogeography, population genetics. At this level, genetic and ecological features of populations, elementary evolutionary factors and their impact on the gene pool (microevolution), the problem of species conservation.

Ecosystem level of organization- this is the level of microecosystems, mesoecosystems, macroecosystems. At this level, types of nutrition are studied, types of relationships between organisms and populations in an ecosystem, population size, population dynamics, population density, ecosystem productivity, successions. This level studies ecology.

Allocate also biospheric level of organization living matter. The biosphere is a giant ecosystem that occupies part of the geographic envelope of the Earth. This is a mega ecosystem. In the biosphere, there is a cycle of substances and chemical elements, as well as the conversion of solar energy.

2. Fundamental properties of living matter

Metabolism (metabolism)

Metabolism (metabolism) is a set of chemical transformations occurring in living systems that ensure their vital activity, growth, reproduction, development, self-preservation, constant contact with the environment, the ability to adapt to it and its changes. In the process of metabolism, splitting and synthesis of molecules that make up cells occur; formation, destruction and renewal of cellular structures and intercellular substance. Metabolism is based on interrelated processes of assimilation (anabolism) and dissimilation (catabolism). Assimilation - the processes of synthesis of complex molecules from simple ones with the expenditure of energy stored during dissimilation (as well as the accumulation of energy during the deposition of synthesized substances in the reserve). Dissimilation - the processes of splitting (anaerobic or aerobic) of complex organic compounds, going with the release of energy necessary for the implementation of the vital activity of the organism. Unlike bodies of inanimate nature, exchange with the environment for living organisms is a condition for their existence. In this case, self-renewal occurs. Metabolic processes occurring inside the body are combined into metabolic cascades and cycles by chemical reactions, which are strictly ordered in time and space. The coordinated flow of a large number of reactions in a small volume is achieved by the ordered distribution of individual metabolic links in the cell (the principle of compartmentalization). Metabolic processes are regulated with the help of biocatalysts - special proteins-enzymes. Each enzyme has substrate specificity to catalyze the conversion of only one substrate. This specificity is based on a peculiar "recognition" of the substrate by the enzyme. Enzymatic catalysis differs from non-biological in its extremely high efficiency, as a result of which the rate of the corresponding reaction increases by 1010 - 1013 times. Each enzyme molecule is capable of performing from several thousand to several million operations per minute without being destroyed in the process of participating in reactions. Another characteristic difference between enzymes and non-biological catalysts is that enzymes are able to accelerate reactions under normal conditions (atmospheric pressure, body temperature, etc.). All living organisms can be divided into two groups - autotrophs and heterotrophs, differing in sources of energy and necessary substances for their life. Autotrophs - organisms that synthesize from inorganic substances organic compounds using the energy of sunlight (photosynthetics - green plants, algae, some bacteria) or the energy obtained from the oxidation of an inorganic substrate (chemosynthetics - sulfur, iron bacteria and some others), Autotrophic organisms are able to synthesize all the components of the cell. The role of photosynthetic autotrophs in nature is decisive - being the primary producer of organic matter in the biosphere, they ensure the existence of all other organisms and the course of biogeochemical cycles in the circulation of substances on Earth. Heterotrophs (all animals, fungi, most bacteria, some chlorophyll-free plants) are organisms that need ready-made organic matter ah, which, acting as food, serve as both a source of energy and a necessary "building material". A characteristic feature of heterotrophs is the presence of amphibolism in them, i.e. the process of formation of small organic molecules (monomers) formed during the digestion of food (the process of degradation of complex substrates). Such molecules - monomers are used to assemble their own complex organic compounds.

Self-reproduction (reproduction)

The ability to reproduce (reproduce their own kind, self-reproduction) refers to one of the fundamental properties of living organisms. Reproduction is necessary in order to ensure the continuity of the existence of species, because. the lifespan of an individual organism is limited. Reproduction more than compensates for the losses caused by the natural extinction of individuals, and thus maintains the preservation of the species in a number of generations of individuals. In the process of evolution of living organisms, the evolution of methods of reproduction took place. Therefore, the current numerous and diverse different types living organisms we find different forms of reproduction. Many types of organisms combine several methods of reproduction. It is necessary to distinguish two fundamentally different types of reproduction of organisms - asexual (primary and more ancient type of reproduction) and sexual. In the process of asexual reproduction, a new individual is formed from one or a group of cells (in multicellular) of the mother organism. In all forms of asexual reproduction, the offspring have a genotype (set of genes) identical to the maternal one. Consequently, all the offspring of one maternal organism turns out to be genetically homogeneous and the daughter individuals have the same set of traits. In sexual reproduction, a new individual develops from a zygote formed by the fusion of two specialized germ cells (fertilization process) produced by two parental organisms. The nucleus in the zygote contains a hybrid set of chromosomes, which is formed as a result of the union of sets of chromosomes of fused gamete nuclei. In the nucleus of the zygote, thus, a new combination of hereditary inclinations (genes) is created, brought in equally by both parents. And the daughter organism developing from the zygote will have a new combination of features. In other words, during sexual reproduction, the implementation of a combinative form of hereditary variability of organisms occurs, which ensures the adaptation of species to changing environmental conditions and is an essential factor in evolution. This is a significant advantage of sexual reproduction over asexual reproduction. The ability of living organisms to self-reproduce is based on the unique property of nucleic acids to reproduce and the phenomenon of matrix synthesis, which underlies the formation of nucleic acid molecules and proteins. Self-reproduction at the molecular level determines both the implementation of metabolism in cells and the self-reproduction of the cells themselves. Cell division (self-reproduction of cells) underlies the individual development of multicellular organisms and the reproduction of all organisms. The reproduction of organisms ensures the self-reproduction of all species inhabiting the Earth, which in turn determines the existence of biogeocenoses and the biosphere.

Heredity and variability

Heredity provides material continuity (the flow of genetic information) between generations of organisms. It is closely related to reproduction at the molecular, subcellular and cellular levels. Genetic information that determines the diversity of hereditary traits is encrypted in the molecular structure of DNA (for some viruses, in RNA). The genes encode information about the structure of synthesized proteins, enzymatic and structural. The genetic code is a system of "recording" information about the sequence of amino acids in synthesized proteins using the sequence of nucleotides in the DNA molecule. The totality of all the genes of an organism is called the genotype, and the totality of traits is called the phenotype. The phenotype depends on both the genotype and the factors of the internal and external environment that affect the activity of genes and determine regular processes. The storage and transmission of hereditary information is carried out in all organisms with the help of nucleic acids, the genetic code is the same for all living beings on Earth, i.e. it is universal. Due to heredity, traits are transmitted from generation to generation that ensure the adaptability of organisms to their environment. If during the reproduction of organisms only the continuity of existing signs and properties was manifested, then against the background of changing environmental conditions, the existence of organisms would be impossible, since a necessary condition for the life of organisms is their adaptability to environmental conditions. There is variability in the diversity of organisms belonging to the same species. Variability can be realized in individual organisms in the course of their individual development or within a group of organisms in a series of generations during reproduction. There are two main forms of variability, which differ in the mechanisms of occurrence, the nature of the change in characteristics and, finally, their significance for the existence of living organisms - genotypic (hereditary) and modification (non-hereditary). Genotypic variability is associated with a change in the genotype and leads to a change in the phenotype. The basis of genotypic variability may be mutations (mutational variability) or new combinations of genes that arise in the process of fertilization during sexual reproduction. In the mutational form, changes are associated primarily with errors in the replication of nucleic acids. Thus, the emergence of new genes that carry new genetic information; new signs appear. And if the newly emerging signs are useful to the organism in specific conditions, then they are "caught up" and "fixed" by natural selection. Thus, the adaptability of organisms to environmental conditions, the diversity of organisms are based on hereditary (genotypic) variability, and the prerequisites for positive evolution are created. With non-hereditary (modification) variability, changes in the phenotype occur under the influence of environmental factors and are not associated with a change in the genotype. Modifications (changes in traits with modification variability) occur within the normal range of the reaction, which is under the control of the genotype. Modifications are not passed on to future generations. The value of modification variability lies in the fact that it ensures the adaptability of the organism to environmental factors during its life.

Individual development of organisms

All living organisms have a process individual development- ontogeny. Traditionally, ontogenesis is understood as the process of individual development of a multicellular organism (formed as a result of sexual reproduction) from the moment of formation of a zygote to the natural death of an individual. Due to the division of the zygote and subsequent generations of cells, a multicellular organism is formed, consisting of a huge number of different types of cells, various tissues and organs. The development of an organism is based on the "genetic program" (embodied in the genes of the chromosomes of the zygote) and is carried out in specific environmental conditions that significantly affect the process of implementing genetic information during the individual existence of an individual. In the early stages of individual development, intensive growth (increase in mass and size) occurs due to the reproduction of molecules, cells and other structures, and differentiation, i.e. appearance of differences in structure and complication of functions. At all stages of ontogenesis, various environmental factors (temperature, gravity, pressure, food composition in terms of the content of chemical elements and vitamins, various physical and chemical agents) have a significant regulatory influence on the development of the organism. The study of the role of these factors in the process of individual development of animals and humans is of great practical importance, which increases with the intensification of anthropogenic impact on nature. IN various fields biology, medicine, veterinary medicine and other sciences, research is being widely conducted to study the processes of normal and pathological development of organisms, to elucidate the patterns of ontogenesis.

Irritability

An integral property of organisms and all living systems is irritability - the ability to perceive external or internal stimuli (impact) and adequately respond to them. In organisms, irritability is accompanied by a complex of changes, expressed in shifts in metabolism, electrical potential on cell membranes, physicochemical parameters in the cytoplasm of cells, in motor reactions, and highly organized animals are characterized by changes in their behavior.

4. Central dogma of molecular biology- a rule generalizing the implementation of genetic information observed in nature: information is transmitted from nucleic acids to squirrel but not in the opposite direction. The rule was formulated Francis Crick in 1958 year and brought into line with the data accumulated by that time in 1970 year. Transfer of genetic information from DNA to RNA and from RNA to squirrel is universal for all cellular organisms without exception; it underlies the biosynthesis of macromolecules. Genome replication corresponds to the DNA → DNA informational transition. In nature, there are also transitions RNA → RNA and RNA → DNA (for example, in some viruses), as well as a change conformations proteins transferred from molecule to molecule.

Universal ways of transferring biological information

In living organisms, there are three types of heterogeneous, that is, consisting of different polymer monomers - DNA, RNA and protein. The transfer of information between them can be carried out in 3 x 3 = 9 ways. The central dogma divides these 9 types of information transfer into three groups:

General - found in most living organisms;

Special - occurring as an exception, in viruses and at mobile elements of the genome or under biological conditions experiment;

Unknown - not found.

DNA replication (DNA → DNA)

DNA is the main way information is transmitted between generations of living organisms, so the exact duplication (replication) of DNA is very important. Replication is carried out by a complex of proteins that unwind chromatin, then a double helix. After that, DNA polymerase and its associated proteins build an identical copy on each of the two strands.

Transcription (DNA → RNA)

Transcription is a biological process, as a result of which the information contained in a DNA segment is copied onto a synthesized molecule. messenger RNA. Transcription is carried out transcription factors And RNA polymerase. IN eukaryotic cell the primary transcript (pre-mRNA) is often edited. This process is called splicing.

Translation (RNA → protein)

Mature mRNA is read ribosomes during the translation process. IN prokaryotic In cells, the process of transcription and translation is not spatially separated, and these processes are conjugated. IN eukaryotic transcription site in cells cell nucleus separated from the broadcast site ( cytoplasm) nuclear membrane, so mRNA transported from the nucleus into the cytoplasm. mRNA is read by the ribosome in the form of three nucleotide"words". complexes initiation factors And elongation factors deliver aminoacylated transfer RNAs to the mRNA-ribosome complex.

5. reverse transcription is the process of forming a double-stranded DNA on a single-stranded matrix RNA. This process is called reverse transcription, since the transfer of genetic information in this case occurs in the “reverse” direction relative to transcription.

The idea of ​​reverse transcription was initially very unpopular, as it contradicted central dogma of molecular biology, which suggested that DNA transcribed to RNA and beyond broadcast into proteins. Found in retroviruses, for example, HIV and in case retrotransposons.

transduction(from lat. transductio- movement) - transfer process bacterial DNA from one cell to another bacteriophage. General transduction is used in bacterial genetics to genome mapping and design strains. Both temperate and virulent phages are capable of transduction; however, the latter destroy the bacterial population; therefore, transduction with their help is of little importance either in nature or in research.

A vector DNA molecule is a DNA molecule that acts as a carrier. The carrier molecule must have a number of features:

Ability to autonomously replicate in a host cell (usually bacterial or yeast)

The presence of a selectable marker

Availability of convenient restriction sites

The most common vectors are bacterial plasmids.

The most difficult thing in life is with simplicity.

A. Koni

ELEMENTAL COMPOSITION OF ORGANISMS

Molecular level of life organization

- this is the level of organization, the properties of which are determined by chemical elements and molecules and their participation in the processes of transformation of substances, energy and information. The application of the structural-functional approach to understanding life at this level of organization allows us to identify the main structural components and processes that determine the structural and functional ordering of the level.

Structural organization of the molecular level. The elementary structural components of the molecular level of life organization are chemical elements as separate types of atoms, and not interconnected and with their own specific properties. The distribution of chemical elements in biosystems is determined precisely by these properties, and depends primarily on the magnitude of the charge of the nucleus. The science that studies the distribution of chemical elements and their significance for biosystems is called biogeochemistry. The founder of this science was the brilliant Ukrainian scientist V. I. Vernadsky, who discovered and explained the connection between living and non-living nature through the biogenic flow of atoms and molecules in the implementation of their basic life functions.

Chemical elements combine to form forgave complex inorganic compounds, which, together with organic substances, are the molecular components of the molecular level of organization. Simple substances (oxygen, nitrogen, metals, etc.) are formed by chemically combined atoms of the same element, and complex substances(acids, salts, etc.) consist of atoms of various chemical elements.

From simple and complex inorganic substances in biological systems are formed intermediate compounds(for example, acetate, keto acids), which form simple organic substances, or small biomolecules. These are, first of all, four classes of molecules - fatty acid, monosaccharides, amino acids and nucleotides. they are called building blocks, since molecules of the next hierarchical sublevel are built from them. Simple structural biomolecules are combined with each other in various ways. covalent bonds, forming macromolecules. They are such important classes as lipids, proteins, oligo- and polysaccharides and nucleic acids.

In biosystems, macromolecules can be combined through non-covalent interactions in supramolecular complexes. They are also called intermolecular complexes, or molecular ensembles, or complex biopolymers (for example, complex enzymes, complex proteins). At the highest, already cellular level of organization, supramolecular complexes are combined with the formation of cellular organelles.

So, the molecular level is characterized by a certain structural hierarchy of molecular organization: chemical elements - simple and complex inorganic compounds - intermediates - small organic molecules - macromolecules - supramolecular complexes.

Molecular level of life organization
The main components that determine the spatial (structural) orderliness	The main processes that determine the time (functional) orderliness
1. Elementary chemical constituents: Organogens; Macronutrients; Microelements; Ultramicroelements. 2. Molecular chemical constituents: Simple inorganic molecules (02 N2, metals) Complex inorganic molecules (water, salts, acids, alkalis, oxides, etc.), Small organic molecules (fatty acids, amino acids, monosaccharides, nucleotides) Macromolecules (lipids, proteins, oligo- and polysaccharides, nucleic acids) supramolecular complexes.	1. Processes of transformation of substances. 2. Energy conversion processes. 3. Processes of transformation of hereditary information

Functional organization at the molecular level . The molecular level of organization of living nature combines a huge number of different chemical reactions, which determine its order in time. Chemical reactions are phenomena in which some substances having a certain composition and properties are converted into other substances. - with a different composition and other properties. reactions between elements, inorganic substances are not specific to living things, specific to life there is a certain order of these reactions, their sequence and combination into an integral system. There are various classifications of chemical reactions. On the basis of changes in the amount of initial and final substances, 4 types of reactions are distinguished: messages, expansions, exchange And substitution. Depending on the use of energy, they emit exothermic(energy is released) and endothermic(energy is absorbed). Organic compounds are also capable of various chemical transformations, which can take place both without changes in the carbon skeleton, and with changes. Reactions without changing the carbon skeleton are substitution, addition, elimination, isomerization reactions. TO reactions with a change in the carbon skeleton include reactions such as chain extension, chain shortening, chain isomerization, chain cyclization, ring opening, ring contraction, and ring expansion. The vast majority of reactions in biosystems are enzymatic and form an aggregate called metabolism. The main types of enzymatic reactions redox, transfer, hydrolysis, non-hydrolytic decomposition, isomerization and synthesis. In biological systems between organic molecules reactions of polymerization, condensation, matrix synthesis, hydrolysis, biological catalysis, etc. can also occur. Most reactions between organic compounds are specific for living nature and cannot occur in inanimate.

Sciences that study the molecular level. The main sciences that study the molecular level are biochemistry and molecular biology. Biochemistry is the science of the essence of life phenomena and their basis is metabolism, and the attention of molecular biology, unlike biochemistry, is focused mainly on the study of the structure and functions of proteins.

Biochemistry - a science that studies the chemical composition of organisms, the structure, properties, significance of the chemical compounds found in them and their transformation in the process of metabolism. The term "biochemistry" was first proposed in 1882, however, it is believed that it gained wide use after the work of the German chemist K. Neuberg in 1903. Biochemistry as an independent science was formed in the second half of the 19th century. thanks to the scientific activity of such famous biochemists as A. M. Butlerov, F. Wehler, F. Misher, A. Ya. Danilevsky, Yu. Liebig, L. Pasteur, E. Buchner, K. A. Timiryazev, M. I. Lunin and others. Modern biochemistry, together with molecular biology, bioorganic chemistry, biophysics, microbiology, constitute a single complex of interrelated sciences - physical and chemical biology, which studies physical and chemical bases living matter. One of the general tasks of biochemistry is to establish the mechanisms of functioning of biosystems and the regulation of cell vital activity, which ensure the unity of metabolism and energy in the body.

Molecular biology - a science that studies biological processes at the level of nucleic acids and proteins and their supramolecular structures. The date of the emergence of molecular biology as an independent science is considered to be 1953, when F. Crick and J. Watson, based on biochemistry and X-ray diffraction data, proposed a model of the three-dimensional structure of DNA, which was called the double helix. The most important sections of this science are molecular genetics, molecular virology, enzymology, bioenergetics, molecular immunology, and molecular developmental biology. The fundamental tasks of molecular biology are the establishment of the molecular mechanisms of the main biological processes due to the structural and functional properties and the interaction of nucleic acids and proteins, as well as the study of the regulatory mechanisms of these processes.

Methods for studying life on molecular level formed mainly in the 20th century. The most common of these are chromatography, ultracentrifugation, electrophoresis, X-ray diffraction analysis, photometry, spectral analysis, tracer method and etc.

All living organisms in nature consist of the same levels of organization; this is a characteristic biological pattern common to all living organisms.
The following levels of organization of living organisms are distinguished - molecular, cellular, tissue, organ, organism, population-species, biogeocenotic, biospheric.

Rice. 1. Molecular genetic level

1. Molecular genetic level. This is the most elementary level characteristic of life (Fig. 1). No matter how complex or simple the structure of any living organism, they all consist of the same molecular compounds. An example of this is nucleic acids, proteins, carbohydrates and other complex molecular complexes of organic and inorganic substances. They are sometimes called biological macromolecular substances. At the molecular level, various life processes of living organisms take place: metabolism, energy conversion. With the help of the molecular level, the transfer of hereditary information is carried out, individual organelles are formed and other processes occur.

Rice. 2. Cellular level

2. Cellular level. The cell is the structural and functional unit of all living organisms on Earth (Fig. 2). Individual organelles in the cell have a characteristic structure and perform a specific function. The functions of individual organelles in the cell are interconnected and perform common life processes. In unicellular organisms (unicellular algae and protozoa), all life processes take place in one cell, and one cell exists as a separate organism. Remember unicellular algae, chlamydomonas, chlorella and protozoa - amoeba, infusoria, etc. In multicellular organisms, one cell cannot exist as a separate organism, but it is an elementary structural unit of the organism.

Rice. 3. Tissue level

3. Tissue level. A set of cells and intercellular substances similar in origin, structure and functions forms a tissue. The tissue level is typical only for multicellular organisms. Also, individual tissues are not an independent integral organism (Fig. 3). For example, the bodies of animals and humans are made up of four different tissues (epithelial, connective, muscle, and nervous). Plant tissues are called: educational, integumentary, supporting, conductive and excretory. Recall the structure and functions of individual tissues.

Rice. 4. Organ level

4. Organ level. In multicellular organisms, the union of several identical tissues, similar in structure, origin, and functions, forms the organ level (Fig. 4). Each organ contains several tissues, but among them one is the most significant. A separate organ cannot exist as a whole organism. Several organs, similar in structure and function, unite to form an organ system, for example, digestion, respiration, blood circulation, etc.

Rice. 5. Organism level

5. Organism level. Plants (chlamydomonas, chlorella) and animals (amoeba, infusoria, etc.), whose bodies consist of one cell, are an independent organism (Fig. 5). A separate individual of multicellular organisms is considered as a separate organism. In each individual organism, all the vital processes characteristic of all living organisms take place - nutrition, respiration, metabolism, irritability, reproduction, etc. Each independent organism leaves behind offspring. In multicellular organisms, cells, tissues, organs and organ systems are not a separate organism. Only an integral system of organs specialized in performing various functions forms a separate independent organism. The development of an organism, from fertilization to the end of life, takes a certain period of time. This individual development of each organism is called ontogeny. An organism can exist in close relationship with the environment.

Rice. 6. Population-species level

6. Population-species level. A set of individuals of one species or group that exists for a long time in a certain part of the range relatively apart from other sets of the same species constitutes a population. At the population level, the simplest evolutionary transformations are carried out, which contributes to the gradual emergence of a new species (Fig. 6).

Rice. 7 Biogeocenotic level

7. Biogeocenotic level. The totality of organisms of different species and organization of varying complexity, adapted to the same environmental conditions, is called a biogeocenosis, or natural community. The composition of biogeocenosis includes numerous types of living organisms and environmental conditions. In natural biogeocenoses, energy is accumulated and transferred from one organism to another. Biogeocenosis includes inorganic, organic compounds and living organisms (Fig. 7).

Rice. 8. Biosphere level

8. Biosphere level. The totality of all living organisms on our planet and their common natural habitat constitutes the biospheric level (Fig. 8). At the biospheric level modern biology decides global problems, for example, determining the intensity of formation of free oxygen by the vegetation cover of the Earth or changes in the concentration carbon dioxide in the atmosphere associated with human activities. The main role at the biospheric level is played by "living substances", that is, the totality of living organisms that inhabit the Earth. Also at the biosphere level, "bio-inert substances" are important, formed as a result of the vital activity of living organisms and "inert" substances (i.e., environmental conditions). At the biospheric level, the circulation of substances and energy on Earth takes place with the participation of all living organisms of the biosphere.

levels of organization of life. population. Biogeocenosis. Biosphere.

1. Currently, there are several levels of organization of living organisms: molecular, cellular, tissue, organ, organism, population-species, biogeocenotic and biospheric.
2. At the population-species level, elementary evolutionary transformations are carried out.
3. The cell is the most elementary structural and functional unit of all living organisms.
4. A set of cells and intercellular substances similar in origin, structure and functions forms a tissue.
5. The totality of all living organisms on the planet and their common natural habitat constitutes the biospheric level.
1. List the levels of organization in order.
2. What is fabric?
3. What are the main parts of a cell?
1. What organisms are characterized by the tissue level?
2. Describe the organ level.
3. What is a population?
1. Describe the organism level.
2. Name the features of the biogeocenotic level.
3. Give examples of the interconnectedness of the levels of organization of life.

Complete the table showing the structural features of each level of the organization:

Serial number	Organization levels	Peculiarities

Life is a multi-level system (from the Greek. system- association, collection). There are such basic levels of organization of living things: molecular, cellular, organ-tissue, organism, population-species, ecosystem, biospheric. All levels are closely interconnected and arise one from the other, which indicates the integrity of living nature.

Molecular level of organization of living

This is the unity of the chemical composition (biopolymers: proteins, carbohydrates, fats, nucleic acids), chemical reactions. From this level, the life processes of the organism begin: energy, plastic and other exchanges, change and implementation of genetic information.

Cellular level of organization of living

Cellular level of organization of the living. animal cage

The cell is the elementary structural unit of the living. This is the unit of development of all living organisms living on Earth. In each cell, the processes of metabolism, energy conversion take place, the preservation, transformation and transfer of genetic information is ensured.

Each cell consists of cellular structures, organelles that perform certain functions, so it is possible to isolate subcellular level.

Organ-tissue level of organization of living

Organ-tissue level of organization of the living. Epithelial tissues, connective tissues, muscle tissues and nerve cells

Cells of multicellular organisms that perform similar functions have the same structure, origin, and unite into tissues. There are several types of tissues that have differences in structure and perform different functions (tissue level).

Tissues in different combinations form different organs that have a certain structure and perform certain functions (organ level).

Organs are combined into organ systems (system level).

Organismal level of organization of living

Organismal level of organization of living

Tissues are combined into organs, organ systems and function as a single whole - the body. The elementary unit of this level is an individual, which is considered in development from the moment of birth to the end of existence as a single living system.

Population-species level of organization of living

Population-species level of organization of living

A set of organisms (individuals) of the same species, having a common habitat, forms populations. A population is an elementary unit of species and evolution, since elementary evolutionary processes take place in it, this and the following levels are supraorganismal.

Ecosystem level of organization of living

Ecosystem level of organization of living

The totality of organisms of different species and levels of organization forms this level. Here we can distinguish biocenotic and biogeocenotic levels.

Populations of different species interact with each other, form multispecies groups ( biocenotic level).

The interaction of biocenoses with climatic and other non-biological factors (relief, soil, salinity, etc.) leads to the formation of biogeocenoses (biogeocenotic). In biogeocenoses, there is a flow of energy between populations of different species and the circulation of substances between its inanimate and living parts.

Biospheric level of organization of living

Biospheric level of organization of living things. 1 - molecular; 2 - cellular; 3 - organism; 4 - population-species; 5 - biogeocenotic; 6 - biospheric

It is represented by a part of the shells of the Earth where life exists - the biosphere. The biosphere consists of a set of biogeocenoses, functions as a single integral system.

It is not always possible to select the entire set of levels listed. For example, in unicellular organisms, the cellular and organismal levels coincide, but the organ-tissue level is absent. Sometimes additional levels can be distinguished, for example, subcellular, tissue, organ, systemic.

9.1. StructurebiologicalknowledgeBiologyhowthe science

Currently, the most dynamically developing science is biology - the science of life and wildlife. The main tasks of biology are to give a scientific definition of life, to point out the fundamental difference between the living and the non-living, to clarify the specifics of the biological form of the existence of matter. The development of biological knowledge leads to a gradual transformation of ideas about the essence of life, the unity of cosmic and biological evolution, the interaction of biological and social in man, etc. New biological data are changing the picture of the world that has been formed by physics for a long time. We can say that today discoveries in biology determine the development of all natural sciences. That is why the modern scientific picture of the world is impossible without biological knowledge. Moreover, biology becomes the basis on which new worldview principles are formed that determine the self-consciousness of a person.

In modern science biology is defined as a set of sciences about wildlife, the diversity of existing and existing living organisms, their structure and functions, origin, distribution and development, relationships with each other and inanimate nature.

In accordance with this, biology studies both general and particular laws of the living in all its manifestations (metabolism, reproduction, heredity, variability, adaptability, etc.).

Modern biology is a dynamic knowledge that is changing before our eyes. The avalanche-like accumulation of new experimental data sometimes outstrips the possibilities of their theoretical interpretation and explanation. In biology, the number of inter-

disciplinary research at the interface with other natural sciences. Therefore, in the structure of biological knowledge today there are more than 50 special sciences: botany, zoology, genetics, molecular biology, anatomy, morphology, cytology, biophysics, biochemistry, paleontology, embryology, ecology, etc. This diversity scientific disciplines is explained mainly by the complexity of the main object of biological research - living matter.

The structure of biology as a science can be viewed from the point of view of objects, properties, levels of organization of the living, main stages and biological paradigms.

According to the objects of study, biology is divided into virology, bacteriology, botany, zoology, anthropology.

According to the properties and manifestations of living things, there is the following classification biological disciplines: embryology - the science that studies the germinal (embryonic) development of organisms; physiology - the science of the functioning of organisms; morphologic - the science of the structure of living organisms; molecular biology - the science of the way of life of flora and fauna communities, their relationship with the environment; genetics - the science of heredity and variation.

According to the level of organization of living organisms, there are: anatomy- the science of the macroscopic structure of animals and humans; histology - the science of tissue structure; cytology - the science of the structure of living cells.

In its development, biology has passed a long and difficult path, which includes three major stages, fundamentally different from each other in their main idea: 1) the period of systematics, 2) the evolutionary period and 3) the period of biology of the microworld. The marked periods do not have clear time boundaries between themselves, just as they do not have sharp transitions. Moreover, since biology has not yet reached the level of theoretical generalizations and does not have its own scientific picture of the world, it exists in three "hypostases" - naturalistic, physicochemical and evolutionary biology. Each of them appeared in a corresponding period in the development of biological science.

Periodsystematics. naturalisticbiology

Like any natural science, biology began to develop as a descriptive (phenomenological) science of diverse forms, types And relationships of the living world. Her main task was to study nature in its natural state. For this, phenomena of living nature were observed, described and systematized. It was during this period that the naturalistic sub-

way to the study of life. the beginning scientific approach served as a constantly growing body of practical knowledge obtained by man in the process of his interaction with the natural environment. In addition to the accumulated knowledge, it was necessary to systematize the objects that were the subject of human practical interests. The idea of ​​systematics originated in antiquity. The first systematizer of science was Aristotle, who collected the factual material accumulated by his time and made the first attempt to classify animals and plants based on the concept of expediency.

He devoted a number of works to the systematization of biological knowledge: "The History of Animals", "On the Parts of Animals", "On the Origin of Animals". In them, Aristotle divided the animal kingdom into two groups: those with blood and those without blood. Among those with blood, he singled out: four-legged viviparous, birds, four-legged and legless oviparous, legless viviparous and fish. Accordingly, those deprived of blood were divided into: soft (cephalopods) soft-skinned many-legged (crayfish), many-legged articulated and shell-like legless (mollusks and sea ​​urchins). In addition, Aristotle identified a number of groups that are transitional between these two. Aristotle assigned a place to man at the top of blood animals (anthropocentrism).

Thanks to the works of Aristotle, chaotic knowledge of living nature acquired a relatively orderly character, and this circumstance gives reason to believe that the formation of biology as a science began in those distant times. Aristotle's ideas enjoyed unquestioned authority right up to modern times, only then they were subjected to verification.

The rise of the biological sciences took place only in the 16th century. and is associated with the era of the great geographical discoveries, which enriched science with many new facts collected on newly discovered lands. These facts required their own systematization and classification, which was proposed in the works of the Swedish scientist K. Linnaeus. In his work "The System of Nature" he was able to develop a harmonious hierarchy of all animals and plants.

The taxonomy of Linnaeus is based on the species, related species are combined into genera, similar genera into orders, and orders into classes. In addition, Linnaeus introduced precise terminology to describe plants and animals. He also owns the introduction of binary (double) nomenclature: the designation of each species with two terms - the name of the genus and species in Latin. Linnaeus accurately determined the relationship between various systematic groups - classes, orders, genera, species and subspecies, clearly identifying the named taxa and showing their hierarchical subordination.

In addition to the systematization and classification of the organic world in the XVIII-XIX centuries. in the field of traditional biology appeared yet

a number of fundamental works that are considered classics of biological thought. These are the 44-volume work of the French scientist J. Buffon and his co-authors "Natural History", the famous "Life of Animals" by A. Brehm and the work of E. Haeckel on the morphology of organisms.

Naturalistic biology has not lost its significance even today. The study of the flora and fauna of our planet is still ongoing, new species are being discovered and described. Despite the fact that modern biology has been able to analyze and classify a huge number of animal and plant organisms, it nevertheless has not been able to make a complete description of everything. natural world. It is believed that only two-thirds of the existing species have been described so far, i.e. 1.2 million animals, 5000 thousand plants, hundreds of thousands of fungi, about 3 thousand bacteria, etc. Ecology is becoming increasingly important - a science that studies the relationship of organisms both with each other and with the environment. This science appeared within the framework of traditional biology, considers nature as a whole and requires a careful, humane attitude towards it.

Periodmicroworld. Physico- chemicalbiology

With all the advantages of naturalistic biology with its holistic approach to the study of nature, biology still needed to understand the mechanisms, phenomena and processes occurring at different levels of life and living organisms. Therefore, from traditional descriptive biology, scientists were forced to move on to the study of the anatomy and physiology of plants and animals, the vital processes of organisms in general and their individual organs, and then deeper and deeper into wildlife, to the study of life at the cellular and molecular-genetic levels.

The foundations of anatomical and physiological knowledge were laid down in antiquity and are associated with the works of Hippocrates, Herophilus, Claudius Galen and their students. However, the true development of this area of ​​biology began only in modern times. In the XVI-XVII centuries. thanks to the research of R. Hooke, N. Grew, J. Helmont, M. Malpighi, carried out using a microscope, the anatomy of plants was developed, the cellular and tissue levels of plant organization were discovered. An experiment, artificial hybridization, penetrates biology, which lays the distant preconditions for the emergence of genetics.

It is important to note that biology in modern times increasingly used the methods of other natural sciences more advanced physics and chemistry. Thus, the idea penetrated into science that all phenomena of life obey the laws of physics and chemistry and can be explained with their help. Thus, biology is increasingly using the ideas of re-

ductionism. At first it was only a methodological approach, but since the 19th century. one could speak of the birth of physicochemical biology, which studied life at the molecular and supramolecular levels. An important role in establishing a new image of biology was played by scientists of the 19th century, who used the methods of physics and chemistry in their research: L. Pasteur, I.M. Sechenov, I.P. Pavlov, I.I. Mechnikov and others. It is also necessary to name the founders of the cellular theory, M. Schleiden and T. Schwann, who in 1838 laid the foundation for the study of the living cell. Their theory led to the emergence of cytology, the science of the living cell.

Further study of the cellular structure caused the birth of genetics - the science of heredity and variability. In the XX century. molecular genetics appeared, which brought biology to a new level of life analysis and brought it even closer to physics and chemistry. It was possible to understand the genetic role of nucleic acids, the molecular mechanisms of genetic reproduction and protein biosynthesis, as well as the molecular genetic mechanisms of variability, were discovered, and metabolism at the molecular level was studied. At the same time, discoveries in physics and chemistry, the continuous improvement of physical and chemical research methods and their application in biology created the opportunity to take a new approach to the study of many biological problems.

From the point of view of chemistry, living organisms are open systems that constantly exchange matter and energy with the environment. At the same time, along with food, they receive a huge amount of organic and mineral compounds, which are involved in the biochemical reactions of the body, and then in the form of decay products are excreted into the environment. The building blocks of a living cell are macromolecules—proteins, fats, carbohydrates, and nucleic acids. Hormonal regulation occurring in the body is also a system of chemical reactions.

The combination of biology and chemistry gave rise to new science- biochemistry, which studies the structure and properties of biomolecules simultaneously with their metabolism in living tissues and organs. In other words, biochemistry analyzes changes in biomolecules within a living organism. Biochemists managed to find out how energy is transferred in a cell, decipher the mechanisms of metabolism (metabolism), establish the role of membranes, ribosomes and other intracellular structures. It was biochemists who deciphered the structure and determined the functions of proteins and nucleic acids, thus laying the foundations of molecular genetics. The recommendations of biochemists today are used by medicine, pharmacy, and agriculture.

Since modern chemistry is based on physics, scientists seek to explain biological phenomena and processes based on

physical laws. As a result, in 1950, at the junction of biochemistry, biology and physics, a new science was born - biophysics. Biophysicists, considering any biological phenomenon, divide it into several more elementary, understandable acts and study them. physical properties. Thus, the mechanisms of muscle contraction, nerve impulse conduction, the secrets of photosynthesis and enzymatic catalysis were explained.

With the help of biochemistry and biophysics, scientists were able to combine knowledge about the structure and functions of the body. But neither these sciences, nor physicochemical biology as a whole, succeed in answering the fundamental question of biology—the question of the origin and essence of life.

Evolutionaryperiod. evolutionarybiology

The idea of ​​the development of wildlife penetrated into biology only in the 19th century, although the prerequisites for evolutionary biology were formed in antiquity. So, Aristotle's systematics of the living is based on the idea of ​​a ladder of beings: he arranged organisms from simple to complex, while he placed a person at the top of the pyramid of the animal world. From this idea, it was only necessary to take a step towards the idea of ​​evolution as the development of the animal world through constant complication.

The beginning of the evolutionary period in the development of biology was laid in the works of the French biologist J. B. Lamarck, who proposed first evolutionary theory. It was outlined in his book "Philosophy of Zoology", published in 1809. Lamarck was the first to talk about changing organisms under the influence of the environment and the transfer of acquired characteristics to descendants. However, Lamarck, in his theory, relied on a number of incorrect starting points, because of which he was unable to resolve the issue of the relationship between internal and external factors of evolution.

A significant contribution to the development of biology at this stage was made by catastrophe theory, the author of which was the French scientist J. Cuvier. He proceeded from the idea that the natural forces that act now and that dominated in the past are qualitatively different from each other. Therefore, in the past, global natural disasters could periodically occur, interrupting the calm course of geological and biological processes on Earth. As a result of these global catastrophes, not only the appearance of the Earth, but also its organic world was almost completely changed. Science is not able to establish the causes of these catastrophes, but we can conclude that it was the catastrophes that led to the emergence of more and more complex organic forms.

A real revolution in biology is associated with the appearance in 1859 of the theories of evolution of Ch. Darwin, set out in his book "The Origin of Species by Means of Natural Selection". evolutionary theory Gift-

wine is built on three postulates: variability, heredity and natural selection. Variability, according to Darwin, is the ability of organisms to acquire new properties and characteristics and change them for various reasons. It is variability that is the first and main link in evolution. Heredity is the ability of living organisms to transmit their properties and characteristics to subsequent generations. Natural selection is the result of the struggle for existence and means the survival and successful reproduction of the fittest organisms. Under the influence of natural selection, groups of individuals of the same species from generation to generation accumulate various adaptive traits and, as a result, acquire such significant differences that they turn into new species. Unfortunately, the provisions on heredity and variability, also included in this theory, were developed much worse. This gave rise to serious criticism of the Darwinian theory of evolution, which unfolded in the late 19th and early 20th centuries.

Modern (synthetic) theory of evolution appeared only towards the end of the 1920s. 20th century It was a synthesis of genetics and Darwinism. Since that time, it has become possible to speak of evolutionary biology as a platform on which the synthesis of heterogeneous biological knowledge takes place. Today's evolutionary biology is the result of the union of two streams of knowledge: evolutionary teaching itself and knowledge gained by other biological sciences about the processes and mechanisms of evolution. Throughout the 20th century the content of evolutionary biology has been constantly expanding. It is supplemented with data from genetics, molecular biology, cytology, and paleontology. Many scientists believe that it is evolutionary biology that can become the foundation of theoretical biology, which is the main goal of biologists of the 21st century.

9.2. Structurallevelsorganizationslife

Life is characterized by the dialectical unity of opposites: it is both integral and discrete. The organic world is a single whole, since it is a system of interconnected parts (the existence of some organisms depends on others), and at the same time it is discrete, since it consists of separate units - organisms, or individuals. Each living organism, in turn, is also discrete, as it consists of individual organs, tissues, cells, but at the same time, each of the organs, having a certain autonomy, acts as part of the whole. Each cell consists of organelles, but functions as a single unit. Hereditary information is carried by genes, but

none of the genes outside of the totality determines the development of the trait, and so on.

The discreteness of life is associated with various levels of organization of the organic world, which can be defined as discrete states of biological systems characterized by subordination, interconnectedness and specific patterns. At the same time, each new level has special properties and patterns of the previous, lower level, since any organism, on the one hand, consists of elements subordinate to it, and on the other, it is itself an element that is part of some kind of macrobiological system.

At all levels of life, its attributes such as discreteness and integrity, structural organization, exchange of matter, energy and information are manifested. The existence of life at higher levels of organization is prepared and determined by the structure of the lower level; in particular, the nature of the cellular level is determined by the molecular and subcellular levels, while the character of the organism is determined by the cellular and tissue levels, and so on.

The structural levels of life organization are extremely diverse, but the main ones are molecular, cellular, ontogenetic, population-species, biocenotic, biogeocenotic and biospheric.

Molecular- geneticlevel

The molecular genetic level of life is the level of functioning of biopolymers (proteins, nucleic acids, polysaccharides) and other important organic compounds that underlie the life processes of organisms. At this level, the elementary structural unit is the gene, and the carrier of hereditary information in all living organisms is the DNA molecule. The implementation of hereditary information is carried out with the participation of RNA molecules. Due to the fact that the processes of storage, change and implementation of hereditary information are associated with molecular structures, this level is called molecular-genetic.

The most important tasks of biology at this level are the study of the mechanisms of transmission of genetic information, heredity and variability, the study of evolutionary processes, the origin and essence of life.

All living organisms contain simple inorganic molecules: nitrogen, water, carbon dioxide. From them, in the course of chemical evolution, simple organic compounds appeared, which, in turn, became the building material for larger molecules. This is how macromolecules appeared - giant mo-

polymer molecules built from many monomers. There are three types of polymers: polysaccharides, proteins and nucleic acids. The monomers for them, respectively, are monosaccharides, amino acids and nucleotides.

Squirrels and nucleic acids are "information" molecules, since the sequence of monomers, which can be very diverse, plays an important role in their structure. Polysaccharides (starch, glycogen, cellulose) play the role of an energy source and building material for the synthesis of larger molecules.

Proteins are macromolecules that are very long chains of amino acids - organic (carboxylic) acids, usually containing one or two amino groups (-NH 2 ).

In solutions, amino acids can exhibit the properties of both acids and bases. This makes them a kind of buffer on the way of dangerous physical and chemical changes. More than 170 amino acids are found in living cells and tissues, but only 20 are included in proteins. It is the sequence of amino acids connected to each other by peptide bonds1 that forms the primary structure of proteins. Proteins account for over 50% of the total dry mass of cells.

Most proteins act as catalysts (enzymes). In their spatial structure there are active centers in the form of recesses of a certain shape. Molecules, the transformation of which is catalyzed by this protein, enter such centers. In addition, proteins play the role of carriers; for example, hemoglobin carries oxygen from the lungs to the tissues. Muscle contractions and intracellular movements are the result of the interaction of protein molecules, the function of which is to coordinate movement. The function of antibody proteins is to protect the body from viruses, bacteria, etc. Activity nervous system depends on proteins that collect and store information from the environment. Proteins called hormones control cell growth and activity.

Nucleic acids. The life processes of living organisms are determined by the interaction of two types of macromolecules - proteins and DNA. The genetic information of an organism is stored in DNA molecules, which serve as a carrier of hereditary information for the next generation and determine the biosynthesis of proteins that control almost all biological processes. So nuk-

1 A peptide bond is a chemical bond —CO-NH-.

Leic acids have the same important place in the body as proteins.

Both proteins and nucleic acids have one very important property - molecular dissymmetry (asymmetry), or molecular chirality. This property of life was discovered in the 1940s and 1950s. 19th century L. Pasteur in the course of studying the structure of crystals of substances of biological origin - salts of tartaric acid. In his experiments, Pasteur discovered that not only crystals, but also their aqueous solutions are capable of deflecting a polarized light beam, i.e. are optically active. Later they were named optical isomers. Solutions of substances of non-biological origin do not have this property, the structure of their molecules is symmetrical.

Today, Pasteur's ideas have been confirmed, and it is considered proven that molecular chirality (from the Greek cheir - hand) is inherent only in living matter and is its integral property. The substance of inanimate origin is symmetrical in the sense that the molecules that polarize light to the left and to the right are always equally divided in it. And in the substance of biological origin there is always a deviation from this balance. Proteins are built from amino acids that polarize light only to the left (L-configuration). Nucleic acids consist of sugars that polarize light only to the right (D-configuration). Thus, chirality lies in the asymmetry of molecules, their incompatibility with their mirror image, as in the right and left hands, which gave the modern name to this property. It is interesting to note that if a person suddenly turned into his mirror image, then everything would be fine with his body until he began to eat food of plant or animal origin, which he simply could not digest.

Nucleic acids are complex organic compounds that are phosphorus-containing biopolymers (polynucleotides).

There are two types of nucleic acids - deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Nucleic acids got their name (from the Latin nucleus - nucleus) due to the fact that they were first isolated from the nuclei of leukocytes in the second half of the 19th century. Swiss biochemist F. Miescher. Later it was found that nucleic acids can be found not only in the nucleus, but also in the cytoplasm and its organelles. DNA molecules together with histone proteins form the substance of chromosomes.

In the middle of the XX century. the American biochemist J. Watson and the English biophysicist F. Crick revealed the structure of the DNA molecule. X-ray diffraction studies have shown that DNA consists of two strands twisted into a double helix. The role of the backbones of the chains is played by sugar-phosphate groups, and the bases of purines and pyrimidines serve as jumpers. Each bridge is formed by two bases attached to two opposite chains, and if one base has one ring, then the other has two. Thus, complementary pairs are formed: A-T and G-C. This means that the sequence of bases in one chain uniquely determines the sequence of bases in another, complementary chain of the molecule.

A gene is a section of a DNA or RNA molecule (in some viruses). RNA contains 4-6 thousand individual nucleotides, DNA - 10-25 thousand. If it were possible to stretch the DNA of one human cell into a continuous thread, then its length would be 91 cm.

Nevertheless, the birth of molecular genetics took place somewhat earlier, when the Americans J. Beadle and E. Tatum established a direct link between the state of genes (DNA) and the synthesis of enzymes (proteins). It was then that the famous saying appeared: "one gene - one protein." Later it was found that the main function of genes is to code for protein synthesis. After that, scientists focused their attention on the question of how the genetic program is written and how it is implemented in the cell. To do this, it was necessary to figure out how just four bases can encode the order in the protein molecules of as many as twenty amino acids. The main contribution to the solution of this problem was made by the famous theoretical physicist G. Gamow in the mid-1950s.

According to him, a combination of three DNA nucleotides is used to encode one amino acid. This elementary unit of heredity, encoding one amino acid, is called codon. In 1961, Gamow's hypothesis was confirmed by F. Crick's research. So the molecular mechanism for reading genetic information from a DNA molecule during protein synthesis was deciphered.

In a living cell there are organelles - ribosomes that "read" the primary structure of DNA and synthesize protein in accordance with the information recorded in DNA. Each triplet of nucleotides is assigned one of the 20 possible amino acids. This is how the primary structure of DNA determines the sequence of amino acids of the synthesized protein, fixes the genetic code of the organism (cell).

The genetic code of all living things, be it a plant, an animal or a bacterium, is the same. Such a feature genetic code together with the similarity of the amino acid composition of all proteins indicates

about the biochemical unity of life, the origin of all living beings on Earth from a single ancestor.

The mechanism of DNA reproduction was also deciphered. It consists of three parts: replication, transcription and translation.

replication is the duplication of DNA molecules. The basis of replication is the unique property of DNA to self-copy, which makes it possible for a cell to divide into two identical ones. During replication, DNA, consisting of two twisted molecular chains, unwinds. Two molecular threads are formed, each of which serves as a matrix for the synthesis of a new thread, complementary to the original one. After that, the cell divides, and in each cell one strand of DNA will be old, and the second will be new. Violation of the sequence of nucleotides in the DNA chain leads to hereditary changes in the body - mutations.

Transcription- this is the transfer of the DNA code by the formation of a single-stranded messenger RNA molecule (i-RNA) on one of the DNA strands. i-RNA is a copy of a part of the DNA molecule, consisting of one or a group of adjacent genes that carry information about the structure of proteins.

Broadcast - This is protein synthesis based on the genetic code of i-RNA in special cell organelles - ribosomes, where transfer RNA (t-RNA) delivers amino acids.

In the late 1950s Russian and French scientists simultaneously put forward a hypothesis that differences in the frequency of occurrence and the order of nucleotides in DNA in different organisms are species-specific. This hypothesis made it possible to study the evolution of living things and the nature of speciation at the molecular level.

There are several mechanisms of variability at the molecular level. The most important of these is the already mentioned mechanism of gene mutation - direct transformation of the genes themselvesnew, located in the chromosome, under the influence of external factors. Factors that cause mutation (mutagens) are radiation, toxic chemical compounds as well as viruses. With this mechanism of variability, the order of the genes in the chromosome does not change.

Another change mechanism is gene recombination. This is the creation of new combinations of genes located on a particular chromosome. At the same time, she molecular basis the gene does not change, but it moves from one part of the chromosome to another or there is an exchange of genes between two chromosomes. Gene recombination occurs during sexual reproduction in higher organisms. In this case, there is no change in the total amount of genetic information, it remains unchanged. This mechanism explains why children only partially resemble their parents −

they inherit traits from both parent organisms that combine randomly.

Another change mechanism is nonclassical recombinationnew It was opened only in the 1950s. With non-classical gene recombination, there is a general increase in the amount of genetic information due to the inclusion of new genetic elements in the cell genome. Most often, new elements are introduced into the cell by viruses. Today, several types of transmissible genes have been discovered. Among them are plasmids, which are double-stranded circular DNA. Because of them, after prolonged use of any drugs, addiction occurs, after which they cease to have a medicinal effect. Pathogenic bacteria, against which our drug acts, bind to plasmids, which makes the bacteria resistant to the drug, and they stop noticing it.

Migrating genetic elements can cause both structural rearrangements in chromosomes and gene mutations. The possibility of using such elements by humans has led to the emergence of a new science - genetic engineering, the purpose of which is to create new forms of organisms with desired properties. Thus, with the help of genetic and biochemical methods, new combinations of genes that do not exist in nature are constructed. For this, the DNA encoding the production of a protein with the desired properties is modified. This mechanism underlies all modern biotechnologies.

Recombinant DNA can be used to synthesize a variety of genes and introduce them into clones (colonies of identical organisms) for directed protein synthesis. So, in 1978, insulin was synthesized - a protein for the treatment of diabetes. The desired gene was introduced into a plasmid and introduced into a normal bacterium.

Geneticists are working to develop safe vaccines against viral infections, since traditional vaccines are a weakened virus that must cause the production of antibodies, so their administration is associated with a certain risk. Genetic engineering makes it possible to obtain DNA encoding the surface layer of the virus. In this case, immunity is produced, but infection of the body is excluded.

Today, in genetic engineering, the issue of increasing life expectancy and the possibility of immortality by changing the genetic program of a person is being considered. This can be achieved by increasing the protective enzyme functions of the cell, protecting DNA molecules from various damages associated with both metabolic disorders and environmental influences. In addition, scientists have managed to discover the aging pigment and create a special drug that frees cells from it. In experiments with we-

shami received an increase in their life expectancy. Also, scientists were able to establish that at the time of cell division, telomeres decrease - special chromosomal structures located at the ends of cell chromosomes. The fact is that during DNA replication, a special substance - polymerase - goes along the DNA helix, making a copy from it. But DNA polymerase does not start copying from the very beginning, but leaves an uncopied tip each time. Therefore, with each subsequent copying, the DNA helix is ​​shortened due to the terminal sections that do not carry any information, or telomeres. As soon as the telomeres are exhausted, subsequent copies begin to contract the part of the DNA that carries the genetic information. This is the process of cell aging. In 1997, an experiment was carried out in the USA and Canada on artificial lengthening of telomeres. For this, a newly discovered cellular enzyme, telomerase, was used, which promotes the growth of telomeres. The cells obtained in this way acquired the ability to divide many times, completely retaining their normal functional properties and not turning into cancer cells.

IN Lately the successes of genetic engineers in the field of cloning became widely known - the exact reproduction of one or another living object in a certain number of copies from somatic cells. At the same time, the grown individual is genetically indistinguishable from the parent organism.

Obtaining clones from organisms that reproduce through parthenogenesis, without prior fertilization, is not something special and has long been used by geneticists. In higher organisms, cases of natural cloning are also known - the birth of identical twins. But the artificial production of clones of higher organisms is associated with serious difficulties. However, in February 1997, a method for cloning mammals was developed at the laboratory of Jan Wilmuth in Edinburgh, and Dolly the sheep was raised with it. To do this, eggs were extracted from a Scottish black-faced sheep, placed in an artificial nutrient medium, and the nuclei were removed from them. Then they took mammary gland cells of an adult pregnant sheep of the Finnish Dorset breed, carrying a complete genetic set. After some time, these cells were fused with non-nuclear eggs and activated their development through electrical discharge. Then the developing embryo grew in an artificial environment for six days, after which the embryos were transplanted into the uterus of the adoptive mother, where they developed until birth. But out of 236 experiments, only one turned out to be successful - Dolly the sheep grew up.

After that, Wilmut announced the fundamental possibility of human cloning, which caused the most lively discussions.

not only in scientific literature, but also in the parliaments of many countries, since such an opportunity is associated with very serious moral, ethical and legal problems. It is no coincidence that some countries have already passed laws prohibiting human cloning. After all, most cloned embryos die. In addition, the probability of the birth of freaks is high. So cloning experiments are not only immoral, but also simply dangerous in terms of maintaining the purity of the species. Homo sapiens. That the risk is too great is confirmed by information that came out in early 2002, reporting that Dolly the sheep was suffering from arthritis, a disease not common in sheep, after which she had to be euthanized shortly after.

Therefore, a much more promising area of ​​research is the study of the human genome (set of genes). In 1988, on the initiative of J. Watson, a international organization"Human Genome", which brought together many scientists from around the world and set the task of deciphering the entire human genome. This is a daunting task, since the number of genes in the human body is from 50 to 100 thousand, and the entire genome is more than 3 billion nucleotide pairs.

It is believed that the first stage of this program, associated with deciphering the sequence of nucleotide pairs, will be completed by the end of 2005. Work has already been done to create an "atlas" of genes, a set of their maps. The first such map was compiled in 1992 by D. Cohen and J. Dosset. In the final version, it was presented in 1996 by J. Weissenbach, who, studying a chromosome under a microscope, marked the DNA of its various regions with special markers. Then he cloned these sections, growing them on microorganisms, and received DNA fragments - the nucleotide sequence of a single strand of DNA that made up the chromosomes. Thus, Weissenbach localized 223 genes and identified about 30 mutations leading to 200 diseases, including hypertension, diabetes, deafness, blindness, and malignant tumors.

One of the results of this program, although not completed, is the possibility of identifying genetic pathologies in the early stages of pregnancy and the creation of gene therapy - a method of treating hereditary diseases using genes. Before the gene therapy procedure, they find out which gene turned out to be defective, get a normal gene and introduce it into all diseased cells. At the same time, it is very important to make sure that the introduced gene works under the control of cell mechanisms, otherwise a cancer cell will be obtained. There are already the first patients cured in this way. True, it is not yet clear how radically they are cured and

whether the disease will return in the future. Also, the long-term consequences of such treatment are not yet clear.

Of course, the use of biotechnology and genetic engineering has both positive and negative sides. This is evidenced by the memorandum published in 1996 by the Federation of European Microbiological Societies. This is due to the fact that the general public is suspicious and hostile towards gene technologies. Fear is caused by the possibility of creating a genetic bomb that can distort the human genome and lead to the birth of freaks; the emergence of unknown diseases and the production of biological weapons.

And, finally, the problem of the widespread distribution of transgenic food products created by introducing genes that block the development of viral or fungal diseases has been widely discussed recently. Transgenic tomatoes and corn have already been created and are being sold. Bread, cheese and beer made with the help of transgenic microbes are supplied to the market. Such products are resistant to harmful bacteria, have improved qualities - taste, nutritional value, strength, etc. For example, in China, virus-resistant tobacco, tomatoes and sweet peppers are grown. Known transgenic tomatoes resistant to bacterial infection, potatoes and corn resistant to fungi. But the long-term consequences of the use of such products are still unknown, primarily the mechanism of their effect on the body and the human genome.

Of course, in twenty years of using biotechnology, nothing that people fear has happened. All new microorganisms created by scientists are less pathogenic than their original forms. There has never been a harmful or dangerous spread of recombinant organisms. However, scientists are careful to ensure that transgenic strains do not contain genes that, when transferred to other bacteria, can have a dangerous effect. There is a theoretical danger of creating new types of bacteriological weapons based on gene technologies. Therefore, scientists must take this risk into account and contribute to the development of a system of reliable international control capable of fixing and suspending such work.

Taking into account the possible danger of using genetic technologies, documents have been developed that regulate their use, safety rules for laboratory research and industrial development, as well as rules for introducing genetically modified organisms into the environment.

Thus, today it is believed that, with appropriate precautions, the benefits of gene technologies outweigh the risk of possible negative consequences.

Cellularlevel

At the cellular level of organization, the basic structural and functional unit of all living organisms is the cell. At the cellular level, as well as at the molecular genetic level, the same type of all living organisms is noted. In all organisms, biosynthesis and realization of hereditary information are possible only at the cellular level. The cellular level in unicellular organisms coincides with the organism level. The history of life on our planet began with this level of organization.

Today, science has precisely established that the smallest independent unit of the structure, functioning and development of a living organism is a cell.

Cell is an elementary biological system, capable of self-renewal, self-reproduction and development, i.e. endowed with all the characteristics of a living organism.

Cellular structures underlie the structure of any living organism, no matter how diverse and complex its structure may seem. The science that studies the living cell is called cytology. It studies the structure of cells, their functioning as elementary living systems, explores the functions of individual cellular components, the process of cell reproduction, their adaptation to environmental conditions, etc. Cytology also studies the features of specialized cells, the formation of their special functions and the development of specific cellular structures. Thus, modern cytology can be called cell physiology. The successes of modern cytology are inextricably linked with the achievements of biochemistry, biophysics, molecular biology and genetics.

Cytology is based on the assertion that all living organisms (animals, plants, bacteria) consist of cells and their metabolic products. New cells are formed by the division of pre-existing cells. All cells are similar chemical composition and metabolism. The activity of the organism as a whole is made up of the activity and interaction of individual cells.

The discovery of the existence of cells came at the end XVII when the microscope was invented. The cell was first described by the English scientist R. Hooke in 1665, when he examined a piece of cork. Since his microscope was not very perfect, what he saw were actually walls of dead cells. It took nearly two hundred years for biologists to realize that leading role it is not the walls of the cell that play, but its internal contents. Among the creators of the cell theory, one should also mention A. Leeuwenhoek, who showed that the tissues of many plant

organisms are built from cells. He also described erythrocytes, unicellular organisms and bacteria. True, Leeuwenhoek, like other researchers of the 17th century, saw in the cell only a shell containing a cavity.

A significant advance in the study of cells occurred at the beginning of the 19th century, when they began to be viewed as individuals with vital properties. In the 1830s the cell nucleus was discovered and described, which drew the attention of scientists to the contents of the cell. Then it was possible to see the division of plant cells. On the basis of these studies, the cell theory was created, which became the greatest event in the biology of the 19th century. It was the cellular theory that gave decisive evidence of the unity of all living nature, served as the foundation for the development of embryology, histology, physiology, the theory of evolution, as well as understanding the individual development of organisms.

Cytology received a powerful impetus with the creation of genetics and molecular biology. After that, new components, or organelles, of cells were discovered - the membrane, ribosomes, lysosomes, etc.

According to modern concepts, cells can exist both as independent organisms (for example, protozoa), and as part of multicellular organisms, where there are germ cells that serve for reproduction, and somatic cells (cells of the body). Somatic cells differ in structure and function - there are nerve, bone, muscle, secretory cells. Cell sizes can vary from 0.1 µm (some bacteria) to 155 mm (ostrich egg in shell). A living organism is formed by billions of various cells (up to 1015), the shape of which can be the most bizarre (spider, star, snowflake, etc.).

It has been established that despite the great variety of cells and the functions they perform, the cells of all living organisms are similar in chemical composition: they contain especially high content of hydrogen, oxygen, carbon and nitrogen (these chemical elements make up more than 98% of the total content of the cell); 2% is accounted for by about 50 other chemical elements.

The cells of living organisms contain inorganic substances- water (on average up to 80%) and mineral salts, as well as organic compounds: 90% of the dry mass of the cell falls on biopolymers - proteins, nucleic acids, carbohydrates and lipids. And finally, it is scientifically proven that all cells consist of three main parts:

the plasma membrane, which controls the passage of substances from the environment into the cell and vice versa;

cytoplasm with a diverse structure;

the cell nucleus, which contains the genetic information.

In addition, all animal and some plant cells contain centrioles, cylindrical structures that form cell centers. Plant cells also have a cell wall (shell) and plastids, specialized cell structures that often contain a pigment that determines the color of the cell.

cell membrane consists of two layers of molecules of fat-like substances, between which there are protein molecules. The membrane maintains the normal concentration of salts inside the cell. When the membrane is damaged, the cell dies.

Cytoplasm is a water-salt solution with enzymes and other substances dissolved and suspended in it. Organelles are located in the cytoplasm - small organs, delimited from the contents of the cytoplasm by their own membranes. Among them - mitochondria- sac-like formations with respiratory enzymes, in which energy is released. Also located in the cytoplasm ribosome, consisting of protein and RNA, with the help of which protein synthesis is carried out in the cell. En-preplasmic reticulum- this is a common intracellular circulatory system, through the channels of which the transport of substances is carried out, and on the membranes of the channels there are enzymes that ensure the vital activity of the cell. plays an important role in the cell glueexact center, consisting of two centrioles. It starts the process of cell division.

The most important part of all cells (except bacteria) is core, in which the chromosomes are located - long thread-like bodies, consisting of DNA and a protein attached to it. The nucleus stores and reproduces genetic information, and also regulates metabolic processes in the cell.

Cells reproduce by dividing the original cell into two daughter cells. In this case, the complete set of chromosomes carrying genetic information is transferred to the daughter cells, therefore, before dividing, the number of chromosomes doubles. Such cell division, which ensures the same distribution of genetic material between daughter cells, is called mitosis.

Multicellular organisms also develop from a single cell, the egg. However, during embryogenesis, cells change. This leads to the appearance of many different cells - muscle, nerve, blood, etc. Different cells synthesize different proteins. However, each cell of a multicellular organism carries a complete set of genetic information to build all the proteins needed for the organism.

Depending on the type of cells, all organisms are divided into two groups:

prokaryotes - cells lacking a nucleus. In them, DNA molecules are not surrounded by a nuclear membrane and are not organized into chromosomes. Prokaryotes include bacteria;

eukaryotes- Cells containing nuclei. In addition, they have mitochondria - organelles in which the oxidation process takes place. Eukaryotes include protozoa, fungi, plants, and animals, so they can be unicellular or multicellular.

Thus, there are significant differences between prokaryotes and eukaryotes in the structure and functioning of the genetic apparatus, cell walls and membrane systems, protein synthesis, etc. It is assumed that the first organisms that appeared on Earth were prokaryotes. This was considered until the 1960s, when in-depth study of the cell led to the discovery of archaebacteria, the structure of which is similar to both prokaryotes and eukaryotes. The question of which unicellular organisms are more ancient, of the possibility of the existence of a certain first cell, from which all three evolutionary lines later appeared, still remains open.

Studying a living cell, scientists drew attention to the existence of two main types of its nutrition, which allowed all organisms to be divided into two species according to the method of nutrition:

autotrophic organisms - organisms that do not need organic food and can carry out their livelihoods through the assimilation of carbon dioxide (bacteria) or photosynthesis (plants), i.e. autotrophs themselves produce the nutrients they need;

heterotrophic organisms are all organisms that cannot live without organic food.

Later, such important factors as the ability of organisms to synthesize the necessary substances (vitamins, hormones, etc.) and provide themselves with energy, dependence on the ecological environment, etc. were clarified. Thus, the complex and differentiated nature of trophic relationships indicates the need systems approach to the study of life and at the ontogenetic level. This is how the concept of functional consistency was formulated by P.K. Anokhin, according to which various components of systems function in concert in unicellular and multicellular organisms. At the same time, individual components contribute to the coordinated functioning of others, thereby ensuring unity and integrity in the implementation of the vital processes of the whole organism. Functional consistency is also manifested in the fact that processes at lower levels are organized by functional links at higher levels of the organization. The functional system character is especially noticeable in multicellular organisms.

ontogeneticlevel. Multicellularorganisms

The main unit of life at the ontogenetic level is an individual, and ontogenesis is an elementary phenomenon. A biological individual can be both a unicellular and a multicellular organism, but in any case it is an integral, self-reproducing system.

Ontogeny called the process of individual development of the organism from birth through successive morphological, physiological and biochemical changes to death, the process of realization of hereditary information.

The minimum living system, the building block of life, is the cell, which is studied by cytology. The functioning and development of multicellular living organisms is the subject of physiology. At present, a unified theory of ontogenesis has not been created, since the causes and factors that determine the individual development of an organism have not been established.

All multicellular organisms are divided into three kingdoms: fungi, plants and animals. The vital activity of multicellular organisms, as well as the functioning of their individual parts, is studied by physiology. This science considers the mechanisms for the implementation of various functions by a living organism, their relationship with each other, the regulation and adaptation of the organism to the external environment, the origin and formation in the process of evolution and individual development of an individual. In fact, this is the process of ontogenesis - the development of the organism from birth to death. In this case, growth, movement of individual structures, differentiation and general complication of the organism occur.

The process of ontogenesis is described on the basis of the famous biogenetic law formulated by E. Haeckel, the author of the term "ontogenesis". The biogenetic law states that ontogeny in brief repeats phylogeny, i.e. an individual organism in its individual development in an abbreviated form goes through all the stages of development of its species. Thus, ontogeny is the implementation of hereditary information encoded in the germ cell, as well as checking the consistency of all body systems during its work and adaptation to the environment.

All multicellular organisms are composed of organs and tissues. Tissues are a group of physically connected cells and intercellular substances to perform certain functions. Their study

is the subject of histology. Tissues can be formed from the same or different cells. For example, in animals, squamous epithelium is built from identical cells, and muscular, nervous, and connective tissues are built from different cells.

Organs are relatively large functional units that combine various tissues into certain physiological complexes. Only animals have internal organs; plants do not have them. In turn, organs are part of larger units - body systems. Among them are the nervous, digestive, cardiovascular, respiratory and other systems.

Actually, a living organism is a special internal environment that exists in the external environment. It is formed as a result of the interaction of a genotype (a set of genes of one organism) with a phenotype (a complex external signs organism, formed in the course of its individual development). Thus, an organism is a stable system of internal organs and tissues existing in the external environment. However, since general theory ontogeny has not yet been created, many processes occurring during the development of the organism have not received their full explanation.

population- specificlevel

The population-species level is the supra-organismal level of life, the basic unit of which is the population.

population- a set of individuals of one species, relatively isolated from other groups of the same species, occupying a certain territory, reproducing itself for a long time and having a common genetic fund.

Unlike the population view called a set of individuals similar in structure and physiological properties, having a common origin, able to freely interbreed and produce fertile offspring. A species exists only through populations that are genetically open systems. Population biology is the study of populations.

In the conditions of real nature, individuals are not isolated from each other, but are united into living systems of a higher rank. The first such system is the population.

The term "population" was introduced by one of the founders of genetics, V. Johansen, who called it a genetically heterogeneous set of organisms, different from a homogeneous set - a pure line. Later this term became more

The integrity of populations, manifested in the emergence of new properties in comparison with the ontogenetic standard of living, is ensured by the interaction of individuals in populations and is recreated through the exchange of genetic information in the process of sexual reproduction. Each population has quantitative boundaries. On the one hand, this is the minimum number that ensures the self-reproduction of the population, and on the other hand, the maximum number of individuals that can feed in the area (habitat) of this population. The population as a whole is characterized by such parameters as the waves of life - periodic fluctuations in numbers, population density, the ratio of age groups and sexes, mortality, etc.

Populations are genetically open systems, since the isolation of populations is not absolute and the exchange of genetic information is periodically possible. It is populations that act as elementary units of evolution; changes in their gene pool lead to the emergence of new species.

The population level of life organization is characterized by active or passive mobility of all components of the population. This entails the constant movement of individuals - members of the population. It should be noted that no population is absolutely homogeneous; it always consists of intrapopulation groups. It should also be remembered that there are populations of different ranks - there are permanent, relatively independent geographical populations, and temporary (seasonal) local populations. At the same time, high abundance and stability are achieved only in those populations that have a complex hierarchical and spatial structure, i.e. are heterogeneous, heterogeneous, have complex and long food chains. Therefore, the loss of at least one link from this structure leads to the destruction of the population or the loss of its stability.

Biocenoticlevel

Populations representing the first supraorganismal level of the living, being elementary units of evolution, capable of independent existence and transformation, are united in the aggregate of the next supraorganismal level - biocenoses.

Biocenosis- the totality of all organisms inhabiting a section of the environment with homogeneous living conditions, for example, a forest, meadow, swamp, etc. In other words, a biocenosis is a set of populations living in a certain territory.

Typically, biocenoses consist of several populations and are a component of more complex system- biogeocenosis.

Biogeocenoticlevel

Biogeocenosis- a complex dynamic system, which is a combination of biotic and abiotic elements interconnected by the exchange of matter, energy and information, within which the circulation of substances in nature can be carried out.

This means that biogeocenosis is a stable system that can exist for a long time. Equilibrium in a living system is dynamic, i.e. represents a constant movement around a certain point of stability. For the stable functioning of a living system, it is necessary to have feedback between its control and controlled subsystems. This way of maintaining dynamic balance is called homeostasis. Violation of the dynamic balance between the various elements of the biogeocenosis, caused by the mass reproduction of some species and the reduction or disappearance of others, leading to a change in the quality of the environment, is called ecological disaster.

The term "biogeocenosis" was proposed in 1940 by the Russian botanist V.N. Sukachev, who designated by this term the

density of homogeneous natural phenomena(atmosphere, rocks, water resources, vegetation, wildlife, soil) distributed over a certain extent of the earth's surface, having a certain type of exchange of matter and energy between them and the surrounding elements, representing a contradictory unity. Representing the unity of living and non-living, biogeocenosis is in constant motion and development, therefore it changes over time.

Biogeocenosis is an integral self-regulating system in which several types of subsystems are distinguished:

primary systems - producers(producing) directly processing inanimate matter (algae, plants, microorganisms);

first order consumers- the secondary level, at which matter and energy are obtained through the use of producers (herbivores);

second order consumers(predators, etc.);

scavengers (saprophytes) And saprophages), eating dead animals;

decomposers - This is a group of bacteria and fungi that decompose the remnants of organic matter.

As a result of the vital activity of saprophytes, saprophages and decomposers, mineral substances return to the soil, which increases its fertility and provides plant nutrition. Therefore, scavengers and decomposers are a very important part of food chains.

The cycle of substances passes through these levels in the biogeocenosis - life is involved in the use, processing and restoration various structures. But the circulation of energy does not occur: from one level to another, higher, about 10% of the energy that has entered the previous level passes. The reverse flow does not exceed 0.5%. In other words, in the biogeocenosis there is a unidirectional energy flow. This makes it an open system, inextricably linked with neighboring biogeocenoses. This connection manifests itself in various forms: gaseous, liquid, solid, and also in the form of animal migration.

Self-regulation of biogeocenoses proceeds the more successfully, the more diverse the number of its constituent elements. The stability of biogeocenoses depends on the variety of components. The loss of one or more components can lead to an irreversible imbalance of the biogeocenosis and its death as an integral system. So, tropical biogeocenoses due to huge amount plants and animals included in them are much more stable than temperate or arctic biogeocenoses, which are poorer in terms of species diversity. For the same reason, the lake, which is

Being a natural biogeocenosis with a sufficient variety of living organisms, it is much more stable than a pond created by man and cannot exist without constant care for it. This is due to the fact that highly organized organisms for their existence need simpler organisms with which they are connected by trophic chains. Therefore, the foundation of any biogeocenosis is the simplest and lower organisms, mostly autotrophic microorganisms and plants. They are directly related to the abiotic components of biogeocenosis - the atmosphere, water, soil, solar energy, which is used to create organic matter. They also constitute the living environment for heterotrophic organisms - animals, fungi, viruses, humans. These organisms, in turn, participate in the life cycles of plants - pollinate, distribute fruits and seeds. This is how the circulation of substances occurs in biogeocenosis, in which plants play a fundamental role. Therefore, the boundaries of biogeocenoses most often coincide with the boundaries of plant communities.

Biogeocenoses are the structural elements of the next superorganismal level of life. They make up the biosphere and determine all the processes occurring in it.

biosphericlevel

The biospheric level is the highest level of life organization, covering all the phenomena of life on our planet.

Biosphere- this is the living substance of the planet (the totality of all living organisms of the planet, including humans) and the environment transformed by it.

Biotic metabolism is a factor that unites all other levels of life organization into one biosphere.

At the biosphere level, there is a circulation of substances and the transformation of energy associated with the vital activity of all living organisms living on Earth. Thus, the biosphere is a single ecological system. The study of the functioning of this system, its structure and functions is the most important task of biology. Ecology, biocenology and biogeochemistry are engaged in the study of these problems.

The concept of the biosphere occupies a key place in the system of the modern scientific worldview. The term "biosphere" itself appeared in 1875. It was introduced by the Austrian geologist and paleontologist E. Suess to designate an independent sphere of our planet.

you, in which there is life. Suess defined the biosphere as a collection of organisms limited in space and time and living on the surface of the Earth. But he did not attach importance to the habitat of these organisms.

However, Suess was not a pioneer, since the development of the doctrine of the biosphere has a rather long prehistory. One of the first to consider the question of the influence of living organisms on geological processes was J. B. Lamarck in his book Hydrogeology (1802). In particular, Lamarck said that all the substances that are on the surface of the Earth and form its crust were formed due to the activity of living organisms. Then there was the grandiose multi-volume work of A. Humboldt "Cosmos" (the first book was published in 1845), in which many facts proved the interaction of living organisms with those earthly shells into which they penetrate. Therefore, Humboldt considered the atmosphere, hydrosphere and land with the living organisms living in them as a single shell of the Earth, an integral system.

But nothing has yet been said about the geological role of the biosphere, its dependence on the planetary factors of the Earth, its structure and functions. The development of the doctrine of the biosphere is inextricably linked with the name of the outstanding Russian scientist V.I. Vernadsky. His concept evolved gradually, from the first student work "On the change in the soil of the steppes by rodents" to "Living Matter", "Biosphere" and "Biogeochemical Essays". The results of his reflections were summed up in the works " Chemical structure Biosphere of the Earth" and "Philosophical Thoughts of a Naturalist", on which he worked in the last decades of his life. It was Vernadsky who managed to prove the connection of the organic world of our planet, acting as a single inseparable whole, with geological processes on Earth, it was he who discovered and studied the biogeochemical functions of living matter.

The key concept in Vernadsky's concept was the concept living matter, by which the scientist understood the totality of all living organisms on our planet, including humans. It also included in the composition of living matter a part of its external environment, which is necessary for maintaining the normal life of organisms; secretions and parts lost by organisms; dead organisms, as well as organic mixtures outside the organisms. Vernadsky considered the most important difference between living matter and inert matter to be the molecular asymmetry of living matter, discovered at one time by Pasteur (molecular chirality in modern terminology). Using this concept, Vernadsky managed to prove that not only the environment affects living organisms, but life is also able to effectively shape

their habitat. Indeed, at the level of an individual organism or biocenosis, it is very difficult to trace the impact of life on the environment. But, having introduced a new concept, Vernadsky reached a qualitatively new level of analysis of life and living things - the biospheric level.

The biosphere, according to Vernadsky, is the living substance of the planet (the totality of all living organisms of the Earth) and the habitat transformed by it (inert matter, abiotic elements), which includes the hydrosphere, the lower part of the atmosphere and top part earth's crust. Thus, it is not biological, geological or geographical concept, and the fundamental concept of biogeochemistry - a new science created by Vernadsky to study the geochemical processes taking place in the biosphere with the participation of living organisms. In the new science, the biosphere began to be called one of the main structural components of the organization of our planet and the near-Earth outer space. This is the sphere in which bioenergetic processes and metabolism are carried out as a result of the activity of life.

Thanks to the new approach, Vernadsky explored life as a powerful geological force, effectively shaping the face of the Earth. Living matter has become the link that connected the history of chemical elements with the evolution of the biosphere. The introduction of a new concept also made it possible to raise and resolve the issue of the mechanisms of the geological activity of living matter, the sources of energy for this.

Living matter and inert matter are constantly interacting in the Earth's biosphere - in the continuous circulation of chemical elements and energy. Vernadsky wrote about the biogenic current of atoms, which is caused by living matter and is expressed in the constant processes of respiration, nutrition and reproduction. For example, the nitrogen cycle is associated with the conversion of atmospheric molecular nitrogen into nitrates. Nitrates are absorbed by plants and, as part of their proteins, get to animals. After the death of plants and animals, their bodies end up in the soil, where putrefactive bacteria decompose organic remains to ammonia, which is then oxidized into nitric acid.

There is a continuous renewal of biomass on Earth (for 7-8 years), while abiotic elements of the biosphere are involved in the cycle. For example, the waters of the World Ocean have passed through the biogenic cycle associated with photosynthesis at least 300 times, the free oxygen of the atmosphere has been renewed at least 1 million times.

Vernadsky also noted that the biogenic migration of chemical elements in the biosphere tends to its maximum manifestation, and the evolution of species leads to the emergence of new species that increase the biogenic migration of atoms.

Vernadsky also noted for the first time that living matter tends to the maximum population of the habitat, and the amount of living matter in the biosphere remains stable throughout entire geological epochs. This value has not changed for at least the last 60 million years. The number of species also remained unchanged. If in some place of the Earth the number of species decreases, then in another place it increases. Today, the disappearance of a huge number of species of plants and animals is therefore associated with the spread of man and his unreasonable activity to transform nature. The population of the Earth is growing due to the death of other species.

Thanks to the biogenic migration of atoms, living matter performs its geochemical functions. modern science classifies them into five categories:

concentration function- is expressed in the accumulation of certain chemical elements both inside and outside living organisms due to their activity. The result was the emergence of mineral reserves (limestone, oil, gas, coal, etc.);

transport function- is closely related to the concentration function, since living organisms carry the chemical elements they need, which then accumulate in their habitats;

energy function - provides energy flows penetrating the biosphere, which makes it possible to carry out all the biogeochemical functions of living matter. The most important role in this process is played by photosynthetic plants that transform solar energy into the biogeochemical energy of the living matter of the biosphere. This energy is spent on all the grandiose transformations of the appearance of our planet;

destructive function - associated with the destruction and processing of organic remains, during which the substances accumulated by organisms are returned to natural cycles, there is a cycle of substances in nature;

environment-forming function- is manifested in the transformation of the environment under the influence of living matter. We can boldly assert that the entire modern appearance of the Earth - the composition of the atmosphere, hydrosphere, upper layer of the lithosphere, most of the minerals, climate - are the result of the action of Life. So, green plants provide the Earth with oxygen and accumulate energy, microorganisms participate in the mineralization of organic substances, the formation of a number of rocks and soil formation.

Despite the grandeur of the tasks that living matter and the biosphere of the Earth solve, the biosphere itself (compared to other geospheres) is a very thin film. Today it is generally accepted that microbial life occurs in the atmosphere up to about 20-22 km above the earth's surface, and the presence of life in deep oceanic depressions lowers this limit to 8-11 km below sea level. Deepening life in the earth's crust much smaller, and microorganisms were found during deep drilling and in formation waters no deeper than 2–3 km. The composition of the biosphere Vernadsky included:

living matter;

biogenic substance - a substance created and processed by living organisms (coal, oil, gas, etc.);

inert matter formed in processes without the participation of living matter;

substances created by living organisms and inert processes, and their dynamic balance;

substances in the process of radioactive decay;

scattered atoms released from terrestrial matter under the influence of cosmic radiation;

a substance of cosmic origin, including individual atoms and molecules penetrating the Earth from space.

Of course, life in the biosphere is distributed unevenly, there are so-called thickening and rarefaction of life. The most densely populated are the lower layers of the atmosphere (50 m from the earth's surface), the illuminated layers of the hydrosphere, and the upper layers of the lithosphere (soil). It should also be noted that the tropical regions are much more densely populated than the deserts or ice fields of the Arctic and Antarctic. Deeper into the earth's crust, into the ocean, and also higher into the atmosphere, the amount of living matter decreases. Thus, this thinnest film of life covers absolutely the entire Earth, leaving not a single place on our planet where there would be no life. At the same time, there is no sharp boundary between the biosphere and the terrestrial shells surrounding it.

For a long time, Vernadsky's ideas were hushed up, and they returned to them only in the mid-1970s. This was largely due to the work of the Russian biologist G.A. Zavarzin, who proved that the main factor in the formation and functioning of the biosphere was and remains multilateral trophic relationships. They were established no less than 3.4-3.5 billion years ago and since then determine the nature and extent of the circulation of elements in the Earth's shells.

In the early 1980s English chemist J. Lovelock and American microbiologist L. Margulis proposed a very interesting concept of Gaia-Earth. According to it, the biosphere is

It is a single superorganism with a developed homeostasis, making it relatively independent of fluctuations in external factors. But if the self-regulating system of Gaia-Earth falls into a state of stress close to the limits of self-regulation, even a small shock can push it to a transition to a new state or even to the complete destruction of the system. In the history of our planet, such things have happened more than once. global catastrophes. The most famous of them is the extinction of dinosaurs about 60 million years ago. Now the Earth is again experiencing a deep crisis, so it is so important to think over a strategy for the further development of human civilization.

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