It is typical for the living nature of our planet complex, hierarchical relationship between levels of organization. The entire organic world and environment forms a biosphere, which, in turn, consists of biogeocenoses (ecosystems) - territories with characteristic natural conditions and certain plant and animal complexes (biocenoses). Biocenoses are formed by populations - groups of plant and animal organisms of the same species, living in a certain territory and capable of producing. Populations consist of representatives of specific species (individuals) capable of interbreeding freely and producing fertile offspring. Multicellular organisms consist of organs and tissues formed by cells. Single-celled organisms and cells are formed by intracellular structures that consist of molecules.

Based on this, we distinguish several levels of organization of living matter.

Each level of organization of living organisms is characterized by its own patterns associated with its specific principles of organization and features of relationships with other levels.

General biology studies the basic patterns of life phenomena that occur on various levels living organizations. Consideration of the organization of living matter begins with elucidation of the structure and properties of complex organic molecules. The cells of multicellular organisms are part of tissues; two or more tissues form an organ. A multicellular organism has complex structure, which consists of tissues and organs, is at the same time an elementary unit of a biological species. By interacting with each other, species form a community, or ecological system, which, in turn, is one of the components of the biosphere.

Each level of organization of organisms is studied by the corresponding branches of biology.

Molecular level

Note 1

Any living system, no matter how complexly it is organized, is determined at the level of functioning of biological macromolecules - biopolymers: nucleic acids, proteins, polysaccharides, as well as other important organic matter. Start from this level critical processes vital functions of the body: metabolism and energy conversion, transmission hereditary information and so on.

Molecular biology, molecular genetics, physiology, cytochemistry, biochemistry, biophysics, certain branches of virology, microbiology are studied physical and chemical processes, occurring in a living organism (synthesis, decomposition and mutual transformations of proteins, nucleic acids, polysaccharides, lipids and other substances in the cell; metabolism, energy and information that regulate these processes).

Such studies of living systems have shown that they consist of low- and high-molecular organic compounds, which are almost impossible to detect in inanimate nature. The most characteristic biopolymers for living organisms are proteins, nucleic acids, polysaccharides, lipids (fat-like compounds) and their constituent molecules (amino acids, nucleotides, monosaccharides, fatty acids). Also, at this level, the synthesis, breakdown and mutual transformations of these compounds in cells, metabolism, energy and information, and the regulation of these processes are studied.

As a result of such studies, it was found that most important feature main metabolic pathways - the action of biological catalysts - enzymes(compounds of protein nature), which strictly selectively affect the speed chemical reactions. The structure of some amino acids, a number of proteins and many simple organic compounds has also been studied. Determined that chemical energy, which is released during biological oxidation (respiration processes, glycolysis), is stored in the form of energy-rich compounds (mainly adenosine phosphorus acids ATP, ADP, etc.), and then is used in processes that require energy (muscle contractions, synthesis and transport of substances). A major success was a discovery genetic code. It was found that heredity encoded in DNA through enzyme proteins controls both structural proteins and all the basic properties of cells and the organism as a whole.

Research on molecular level require the isolation and study of all types of molecules that make up the cell, revealing their relationship with each other.

Research methods used at the molecular level:

• electrophoresis (to separate macromolecules using their differences in charges);
• ultracentrifugation (to separate macromolecules using their differences in density and size);
• chromatography (to separate macromolecules using their differences in adsorption properties);
• X-ray diffraction analysis (study the relative spatial arrangement of atoms in complex molecules);
• radioisotopes (study of pathways of transformation of substances, the rate of their synthesis and decay);
• artificial modeling of systems from isolated cellular elements (reproduction of processes occurring in the cell - all biochemical processes in a cell occur not in a homogeneous mixture of substances, but on certain cellular structures Oh).

Cellular level

At the cellular level cytology, histology, and their departments (karyology, cyto- and histochemistry, cytophysiology, cytogenetics), many sections of physiology, microbiology and virology study the structure of the cell and internal cellular components, as well as connections and relationships between cells in the tissues and organs of the body. There are no free-living non-cellular life forms.

Cell- the main independent functional and structural unit of a multicellular organism. There are single-celled organisms (algae, fungi, protozoa, bacteria). Also, the cell is the unit of development of all living organisms that exist on Earth. The properties of a cell are determined by its components, which perform various functions.

Thanks to research at the cellular level, the main components of the cell, the structure of cells and tissues, and their changes during development have been studied.

Research methods at the cellular level:

• microscopy (light microscope allows you to see objects down to 1 micron);
• color histochemical reactions (detection of localization in the cell of various chemical substances and enzymes);
• autoradiography (detection of sites of macromolecule synthesis in the cell);
• electron microscopy (distinguishing structures down to macromolecules, although describing their structure is often difficult due to insufficient image contrast);
• centrifugation (study of the functions of intracellular components - they are isolated from destroyed (homogenized) cells);
• tissue culture (study of cell properties);
• microsurgery (exchange of nuclei between cells, fusion (hybridization) of cells.

Tissue level

Tissue is a collection of cells similar in structure, united by execution general function. Hundreds of different cells make up the body of a variety of multicellular organisms. A variety of animal cells form four types of tissue: nervous, connective, epithelial and muscle. Plants are divided into formative and permanent tissues. Permanent tissues include integumentary, conductive, mechanical and ground tissue.

Organ level

Definition 2

Organs- these are highly differentiated parts of the body that are located in a specific place and perform special functions. These are structural and functional combinations of several types of tissues. They are formed during development from cells of various tissues.

Groups different organs function collectively to perform a common function for the organism. A person has the following organ systems: digestive, respiratory, cardiovascular, nervous, secretory, excretory, reproductive, endocrine, muscular, skeletal and integumentary tissue system. Each individual organ of the system performs a specific function, but all work together as one “team”, ensuring maximum efficiency of the entire system. All organ systems function in interconnection and are regulated by the nervous and endocrine systems. Impaired functioning of any organ leads to pathology of the entire system and even the body.

Organismal level

Physiology (plants and animals, higher nervous activity), experimental morphology, endocrinology, embryology, immunology, as well as a number of other biological branches study the processes and phenomena occurring in an individual, and the coordinated functioning of its organs and systems.

At this level, in order to create a general theory of ontogenesis, research is carried out aimed at revealing the causal mechanisms of the formation biological organization, its differentiation and integration, the implementation of genetic information in ontogenesis. The mechanisms of operation of organs and their systems, their role in the life of the body, the mutual influence of organs, nervous and humoral regulation their functions, animal behavior, adaptive changes, etc.

At this level, the mechanism of operation of organs and systems, their role in the life of the body, the relationships of organs, the behavior of organisms, and adaptive changes are also studied.

IN this moment research methods used:

• electrophysiological(consist of abduction, amplification and registration of bioelectric potentials);
• biochemical(study underway) endocrine regulation- isolation and purification of hormones, synthesis of their analogues, study of biosynthesis and mechanisms of action of hormones);
• cybernetic(research of the GNI of animals and humans using the modeling method);
• experimental(production conditioned reflexes, setting goals).

Population-species level

Definition 3

Certain branches of biology (morphology, physiology, genetics, ecology) study the elementary unit evolutionary process - population- a collection of individuals of the same species inhabiting a certain territory, more or less isolated from neighboring groups.

The study of population composition and dynamics is inextricably linked to the molecular, cellular and organismal levels.

Research methods are the methods of those sciences that study questions specifically posed at this level:

• genetic methods - distribution patterns hereditary characteristics in populations;
• morphological
• physiological
• environmental.

A population and a species as a whole can serve as objects of study in a wide variety of biological branches.

Biogeocenotic, or biosphere, level

Definition 4

Biogeocenology, ecology, biogeochemistry and other branches of biology study the processes occurring in biogeocenoses(ecosystems) - elementary structural and functional units of the biosphere.

At this level there are comprehensive research, covering the relationships between biotic and abiotic components that are part of the biogeocenosis; the movement of living matter in the biosphere, the paths and patterns of energy circulation are studied. This approach makes it possible to foresee the consequences economic activity human and in uniform international program“Man and the Biosphere” coordinates the efforts of biologists from many countries.

Important practical significance has studying biological productivity biogeocenoses (energy utilization solar radiation through photosynthesis and the use of energy stored by autotrophs by heterotrophic organisms).

Note 2

The need for a detailed study of the biosphere level of organization of living things is determined by the fact that biogeocenoses are the environment in which any life processes on our planet take place.

By the 1960s in biology there is an idea about the levels organization of living things as a concrete expression of increasingly complex orderlinessorganic world. Life on Earth is represented by peculiar organismsstructures belonging to certain systematic groups (species), as well ascommunities of varying complexity (biogeocenosis, biosphere). In turn, organismscharacterized by organ, tissue, cellular and molecular organization.Each organism, on the one hand, consists of specialized subordinatessystems of organization (organs, tissues, etc.), on the other hand, it itself isa relatively isolated unit within supraorganismal biologicalsystems (species, biogeocenoses and the biosphere as a whole). Levels of organization livematter are presented in Fig. 1

Fig.1. Levels of organization of living things

All of them exhibit such properties of life as discreteness and integrity. The body consists of various components- organs, but at the same time, thanks to their interaction, it is integral. A species is also an integral system, although it is formed by separate units - individuals, but their interaction maintains the integrity of the species. The existence of life at all levels is ensured by the structure lowest rank. For example, the nature of the cellular level of organization is determined by the subcellular and molecular levels; organismic - organ; tissue, cellular; species - organismal, etc. It should be especially noted the great similarity of units of organization at lower levels and the ever-increasing difference at higher levels (Table 1).

Table 1

Characteristics of the levels of organization of living things

Level Brief description
Molecular	The monotony of organizational units is revealed. Hereditary information in all organisms is contained in DNA (deoxyribonucleic acid) molecules, consisting of only 4 types of nucleotides. Basic organic components living proteins consist of 20 amino acids. Energy processes occurring in organisms are associated with the universal “energy carrier” - ATP (adenosine triphosphate)
Subcellular	There are relatively few (several dozen) main cellular components in pro- and eukaryotic cells
Cellular	The entire set of living beings is divided into two groups - prokaryotic and eukaryotic organisms. This division is based on the criterion of the basic structure of two types of cells. Of course, the diversity of cells in different organisms cannot be denied. However, these differences do not go beyond the two types of cellular organization mentioned above.
Organ-tissue	A collection of cells identical in structure and function makes up tissue. The great similarity between all organisms remains at this level: in multicellular animals there are only four main tissues (epithelial, connective, nervous, muscle), in plants there are six (integumentary, basal, mechanical, conductive, excretory, educational)
Organismal	Characterized by a wide variety of shapes
Species	Today science has described more than 2 million species of living organisms

The human body is in constant interaction with abiotic and biotic factors environment that influences and changes it. The origin of man has been of interest to science for a long time, and theories of its origin are varied. This is also the fact that man originated from a small cell, which gradually, forming colonies of similar cells, became multicellular and in the process of a long course of evolution turned into an anthropoid ape, and which, thanks to work, became a man.

The concept of levels of organization of the human body

In the process of studying in general education high school in biology lessons, the study of a living organism begins with studying plant cell and its components. Already in high school, during lessons, schoolchildren are asked the question: “Name the levels of organization of the human body.” What it is?

The concept of “levels of organization of the human body” is usually understood as its hierarchical structure from a small cell to the organism level. But this level is not the limit, and it is completed by the supraorganismal order, which includes the population-species and biosphere levels.

When highlighting the levels of organization of the human body, their hierarchy should be emphasized:

1. Molecular genetic level.
2. Cellular level.
3. Tissue level.
4. Organ level
5. Organismic level.

Molecular genetic level

The study of molecular mechanisms allows us to characterize it by such components as:

• carriers of genetic information - DNA, RNA.
• biopolymers are proteins, fats and carbohydrates.

At this level, genes and their mutations are identified as a structural element, which determine variability at the organismal and cellular level.

The molecular genetic level of organization of the human body is represented by genetic material, which is encoded in a chain of DNA and RNA. Genetic information reflects such important components of the organization of human life as morbidity, metabolic processes, type of constitution, gender component and individual characteristics person.

The molecular level of organization of the human body is represented by metabolic processes, which consist of assimilation and dissimilation, regulation of metabolism, glycolysis, crossing over and mitosis, meiosis.

Property and structure of the DNA molecule

The main properties of genes are:

• convariant reduplication;
• ability for local structural changes;
• transmission of hereditary information at the intracellular level.

The DNA molecule consists of purine and pyrimidine bases, which are connected by hydrogen bonds to each other and require the enzyme DNA polymerase to join and break them. Convariant reduplication occurs according to the matrix principle, which ensures their connection at the residue of the nitrogenous bases guanine, adenine, cytosine and thymine. This process occurs in 100 seconds, and during this time 40 thousand pairs of nucleotides are assembled.

Cellular level of organization

Studying the cellular structure of the human body will help to understand and characterize the cellular level of organization of the human body. The cell is a structural component and consists of elements periodic table D.I. Mendeleev, of which the most predominant are hydrogen, oxygen, nitrogen and carbon. The remaining elements are represented by a group of macroelements and microelements.

Cell structure

The cell was discovered by R. Hooke in the 17th century. Main structural elements cells are the cytoplasmic membrane, cytoplasm, cell organelles and nucleus. Cytoplasmic membrane consists of phospholipids and proteins as structural components to provide the cell with pores and channels for the exchange of substances between cells and the entry and exit of substances from them.

Cell nucleus

The cell nucleus consists of the nuclear envelope, nuclear sap, chromatin and nucleoli. The nuclear envelope performs a formative and transport function. Nuclear sap contains proteins that are involved in the synthesis of nucleic acids.

• storage of genetic information;
• reproduction and transmission;
• regulation of cell activity in its life-supporting processes.

Cell cytoplasm

The cytoplasm consists of organelles general purpose and specialized. Organelles of general purpose are divided into membrane and non-membrane.

The main function of the cytoplasm is the constancy of the internal environment.

Membrane organelles:

• Endoplasmic reticulum. Its main tasks are the synthesis of biopolymers, intracellular transport of substances, and is a depot of Ca+ ions.
• Golgi apparatus. Synthesizes polysaccharides, glycoproteins, participates in protein synthesis after its release from endoplasmic reticulum, carries out transport and fermentation of secretions in the cell.
• Peroxisomes and lysosomes. They digest absorbed substances and break down macromolecules, neutralizing toxic substances.
• Vacuoles. Storage of substances and metabolic products.
• Mitochondria. Energy and respiratory processes inside the cell.

Non-membrane organelles:

• Ribosomes. Proteins are synthesized with the participation of RNA, which transfers genetic information about the structure and synthesis of proteins from the nucleus.
• Cellular center. Participates in cell division.
• Microtubules and microfilaments. They perform a supporting and contractile function.
• Cilia.

Specialized organelles are the sperm acrosome, small intestinal microvilli, microtubules and microcilia.

Now, to the question: “Characterize the cellular level of organization of the human body,” we can safely list the components and their role in organizing the structure of the cell.

Tissue level

In the human body, it is impossible to distinguish a level of organization in which some tissue consisting of specialized cells would not be present. Tissues are composed of cells and intercellular substance and, according to their specialization, are divided into:

• Nervous. Integrates the external and internal environment, regulates metabolic processes and higher nervous activity.

The levels of organization of the human body smoothly transition into each other and form an integral organ or system of organs that line many tissues. For example, gastrointestinal tract, which has a tubular structure and consists of a serous, muscular and mucous layer. In addition, it has blood vessels that feed it and a neuromuscular system that it controls nervous system, also many enzymatic and humoral control systems.

Organ level

All levels of organization of the human body listed earlier are components of organs. Organs perform specific functions to ensure constancy of the internal environment and metabolism in the body and form systems of subsystems subordinate to it, which perform a specific function in the body. For example, respiratory system consists of the lungs, airways, and respiratory center.

The levels of organization of the human body as a single whole represent an integrated and completely self-sustaining system of organs that forms the body.

The body as a whole

The combination of systems and organs forms an organism in which the integration of systems, metabolism, growth and reproduction, plasticity, and irritability takes place.

There are four types of integration: mechanical, humoral, nervous and chemical.

Mechanical integration is carried out by intercellular substance, connective tissue, and auxiliary organs. Humoral - blood and lymph. Nervous is the highest level of integration. Chemical - hormones of the endocrine glands.

The levels of organization of the human body are a hierarchical complication in the structure of its body. The organism as a whole has a physique - an external integrated form. Physique is external person, which has different gender and age characteristics, structure and position of internal organs.

There are asthenic, normosthenic and hypersthenic types of body structure, which are differentiated by height, skeleton, muscles, and the presence or absence of subcutaneous fat. Also, depending on your body type, organ systems have different structures and positions, sizes and shapes.

The concept of ontogenesis

The individual development of an organism is determined not only by genetic material, but also by external environmental factors. Levels of organization of the human body, the concept of ontogenesis, or the individual development of the organism in the process of its development, uses different genetic materials involved in the functioning of the cell during its development. The work of genes is influenced by the external environment: through environmental factors, renewal occurs, the emergence of new genetic programs, mutations.

For example, hemoglobin changes three times throughout development human body. Proteins that synthesize hemoglobin go through several stages from fetal hemoglobin, which passes into fetal hemoglobin. As the body matures, hemoglobin transforms into its adult form. These ontogenetic characteristics of the level of development of the human body briefly and clearly emphasize that the genetic regulation of the organism performs important role in the process of development of the organism from cells to systems and the organism as a whole.

The study of organization allows us to answer the question: “What are the levels of organization of the human body?” The human body is regulated not only by neurohumoral mechanisms, but also by genetic ones, which are located in every cell of the human body.

The levels of organization of the human body can be briefly described as a complex subordinate system, which has the same structure and complexity as the entire system of living organisms. This pattern is an evolutionarily fixed feature of living organisms.

Levels of organization of living matter- hierarchically subordinate to the level of organization of biosystems, reflecting the levels of their complexity. Most often, six main structural levels of life are distinguished: molecular, cellular, organismal, population-species, biogeocenotic and biosphere. Typically, each of these levels is a system of lower-level subsystems and a subsystem of a higher-level system.

It should be emphasized that constructing a universal list of levels of biosystems is impossible. It is advisable to single out a separate level of organization if new properties appear on it that are absent in systems more low level. For example, the phenomenon of life arises at the cellular level, and potential immortality - at the population level. When researching various objects or various aspects Their functioning can be distinguished by different sets of levels of organization. For example, at single-celled organisms the cellular and organismal levels coincide. When studying the proliferation (reproduction) of cells at the multicellular level, it may be necessary to distinguish separate tissue and organ levels, since the tissue and organ may be characterized by specific mechanisms for regulating the process under study.

One of the conclusions arising from the general theory of systems is that biosystems at different levels can be similar in their essential properties, for example, the principles of regulation of parameters important for their existence

Molecular level of life organization

These are classes of organic compounds specific to living organisms (proteins, fats, carbohydrates, nucleic acids, etc.), their interaction with each other and with inorganic components, their role in metabolism and energy in the body, storage and transmission of hereditary information. This level can be called the initial, deepest level of organization of living things. Every living organism consists of molecules of organic substances - proteins, nucleic acids, carbohydrates, fats, located in cells. Relationship between molecular and what follows cellular level is ensured by the fact that molecules are the material from which supramolecular cellular structures are created. Only by studying the molecular level can one understand how the processes of the origin and evolution of life on our planet proceeded, what molecular basis heredity and metabolic processes in the body. After all, it is at the molecular level that the transformation of all types of energy and metabolism in the cell occurs. The mechanisms of these processes are also universal for all living organisms.

Components

• Molecules of inorganic and organic compounds
• Molecular complexes of chemical compounds (membrane, etc.)

Basic processes

• Combining molecules into special complexes
• Carrying out physical and chemical reactions in an orderly manner
• DNA copying, coding and transmission of genetic information

• Biochemistry
• Biophysics
• Molecular biology
• Molecular genetics

Cellular level of life organization

Represented by free-living unicellular organisms and cells included in multicellular organisms.

Components

• Complexes of molecules of chemical compounds and cell organelles.

Basic processes

• Biosynthesis, photosynthesis
• Regulating chemical reactions
• Cell division
• Attraction chemical elements Earth and solar energy in the biosystem

Sciences conducting research at this level

• Genetic Engineering
• Cytogenetics
• Cytology
• Embryology Geology

Tissue level of life organization

The tissue level is represented by tissues that unite cells of a certain structure, size, location and similar functions. Tissues arose during historical development together with richoclitinism. In multicellular organisms, they are formed during ontogenesis as a consequence of cell differentiation. In animals, there are several types of tissue (epithelial, connective, muscle, nervous, as well as blood and lymph). In plants, there are meristematic, protective, main and leading tissues. At this level, cell specialization occurs.

Scientific disciplines that carry out research at this level: histology.

Organ level of life organization

The organ level is represented by the organs of organisms. In the simplest, digestion, respiration, circulation of substances, excretion, movement and reproduction are carried out due to various organelles. In more advanced organisms are organ systems. In plants and animals, organs are formed from different amounts of tissue. Vertebrates are characterized by cephalization of what is protected in concentration the most important centers and sense organs in the head.

Organismic level of life organization

Represented by unicellular and multicellular organisms of plants, animals, fungi and bacteria.

Components

• Cell - main structural component body. The tissues and organs of multicellular organisms are formed from cells

Basic processes

• Metabolism (metabolism)
• Irritability
• Reproduction
• Ontogenesis
• Neurohumoral regulation of vital processes
• Homeostasis

Sciences conducting research at this level

• Anatomy
• Biometrics
• Morphology
• Physiology
• Histology

Population-species level of life organization

Represented in nature by a huge variety of species and their populations.

Components

• Groups of related individuals united by a specific gene pool and specific interaction with the environment

Basic processes

1. Genetic distinctiveness
2. Interactions between individuals and populations
3. Accumulation of elementary evolutionary transformations
4. Implementation of microevolution and development of adaptation to a changing environment

• Speciation

1. Increased biodiversity

Sciences conducting research at this level

• Population genetics
• Evolution theory
• Ecology

Biogeocenotic level of life organization

Represented by a diversity of natural and cultural ecosystems in all living environments.

Components

• Populations of various species
• Environmental factors
• Food webs, flows of matter and energy

Basic processes

• Biochemical cycle of substances and flow of energy that support life
• Movable balance between living organisms and the abiotic environment (homeostasis)
• Providing living organisms with living conditions and resources (food and shelter)

Sciences conducting research at this level

• Biogeography
• Biogeocenology
• Ecology

Biosphere level of life organization

Featured above global form organization of biological systems - the biosphere.

Components

• Biogeocenoses
• Anthropogenic impact

Basic processes

• Active interaction of living and nonliving matter of the planet
• Biological cycle of substances and energy
• Active biogeochemical human participation in all processes of the biofera, its economic and ethnocultural activities

Sciences conducting research at this level

• Ecology
  • Global ecology
  • Space ecology
  • Social ecology

Basic properties of living organisms. Questions about the origin of life, patterns of historical development in various geological epochs have always been interested in humanity. The concept of life covers the totality of all living organisms on Earth and the conditions of their existence.
The essence of life is that living organisms leave behind offspring. Hereditary information is passed on from generation to generation, organisms self-regulate and recover during the reproduction of offspring. Life is a special quality highest form matter, capable of self-reproduction, leaving offspring.
The concept of life in different historical periods were given various definitions. The first is scientific correct definition gave F. Engels: “Life is a way of existence of protein bodies, and this way of existence consists essentially in the constant self-renewal of chemical components these bodies." When the metabolic process between living organisms and the environment ceases, proteins disintegrate and life disappears. Based on modern achievements biological science, the Russian scientist M.V. Volkenstein gave a new definition to the concept of life: “Living bodies that exist on Earth are open, self-regulating and self-reproducing systems built from biopolymers - proteins and nucleic acids.” This definition does not deny the presence of life on other planets outer space. Life is called an open system, as indicated by continuous process exchange of substances and energy with the environment.
Based on the latest scientific achievements of modern biological science, it is given following definition life: “Life is an open, self-regulating and self-reproducing system of aggregates of living organisms, built from complex biological polymers - proteins and nucleic acids.”
Nucleic acids and proteins are considered the basis of all living things, since they function in the cell and form complex compounds that are part of the structure of all living organisms.
,

Basic properties of living organisms

Living organisms are different from inanimate nature their inherent properties. TO characteristic properties living organisms include: unity chemical composition, metabolism and energy, similarity of levels of organization. Living organisms are also characterized by reproduction, heredity, variability, growth and development, irritability, discreteness, self-regulation, rhythm, etc.

Levels of life organization

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, organismal, population-species, biogeocenotic, biosphere.
1. Molecular genetic level. This is the most elementary level characteristic of life. 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 occur: 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.
2. Cellular level. The cell is the structural and functional unit of all living organisms on Earth. Individual organelles within a cell have a characteristic structure and perform a specific function. The functions of individual organelles in a cell are interconnected and perform common vital processes. In unicellular organisms ( unicellular algae and the simplest) all life processes take place in one cell, and one cell exists as a separate organism. Remember unicellular algae, chlamydomonas, chlorella and protozoa - amoeba, ciliates, etc. In multicellular organisms, one cell cannot exist as a separate organism, but it is elementary structural unit body.

Tissue level

A collection of cells and intercellular substances similar in origin, structure and function forms tissue. The tissue level is characteristic only of multicellular organisms. Also, individual tissues are not an independent integral organism. For example, the bodies of animals and humans consist of four different tissues (epithelial, connective, muscle, nervous). Plant tissue are called: educational, integumentary, supporting, conductive and excretory. Remember the structure and functions of individual tissues.

Organ level

In multicellular organisms, the combination of several identical tissues, similar in structure, origin and function, forms organ level. 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, combine to form an organ system, for example, digestion, respiration, blood circulation, etc.

Organismal level

Plants (Chlamydomonas, Chlorella) and animals (amoeba, ciliates, etc.), whose bodies consist of one cell, represent an independent organism) And an individual individual of multicellular organisms is considered as a separate organism. In each individual organism, all life processes characteristic of all living organisms occur - nutrition, respiration, metabolism, irritability, reproduction, etc. Each independent organism leaves behind offspring. In multicellular organisms, cells, tissues, organs and organ systems are not separate organism. Only an integral system of organs that specifically perform 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 ontogenesis. An organism can exist in close relationship with its environment.

Population-species level

A collection of individuals of one species or group that exists for a long time in a certain part of the range, relatively separately from other populations of the same species, constitutes a population. At the population level, simple evolutionary transformations are carried out, which contributes to the gradual emergence of a new species.

Biogeocenotic level

Collection of organisms different types and varying complexity of organizations, adapted to the same conditions natural environment, is called biogeocenosis, or natural community. The biogeocenosis includes numerous species of living organisms and natural environmental conditions. In natural biogeocenoses, energy accumulates and is transferred from one organism to another. Biogeocenosis includes inorganic, organic compounds and living organisms.

Biosphere level

The totality of all living organisms on our planet and their common natural habitat constitutes the biosphere level. At the biosphere level modern biology decides global problems, for example, determining the intensity of formation of free oxygen by the Earth's vegetation or changes in concentration carbon dioxide in the atmosphere associated with human activities. The main role at the biosphere level is played by “living substances,” that is, the totality of living organisms inhabiting 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 biosphere level, the circulation of substances and energy occurs on Earth with the participation of all living organisms of the biosphere.

Levels of life organization

Levels of organization of the organic world are discrete states of biological systems, characterized by subordination, interconnectedness, and specific patterns.

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

1. Molecular genetic level life. The most important tasks of biology at this stage are the study of the mechanisms of transmission of genetic information, heredity and variability.

There are several mechanisms of variability at the molecular level. The most important of them is the mechanism of gene mutation - the direct transformation of the genes themselves under the influence external factors. Factors causing mutation, are: radiation, toxic chemical compounds, viruses.

Another mechanism of variability is gene recombination. This process occurs during sexual reproduction in higher organisms. In this case, there is no change in the total amount of genetic information.

Another mechanism of variability was discovered only in the 1950s. This is a non-classical recombination of genes in which overall increase volume of genetic information due to the inclusion of new genetic elements in the cell genome. Most often, these elements are introduced into the cell by viruses.

2. Cellular level. Today, science has reliably established that the smallest independent unit of structure, functioning and development of a living organism is the cell, which is an elementary biological system capable of self-renewal, self-reproduction and development. Cytology is the science that studies living cell, its structure, functioning as an elementary living system, studies the functions of individual cellular components, the process of cell reproduction, adaptation to environmental conditions, etc. Cytology also studies the characteristics of specialized cells, their formation special functions and development of specific cellular structures. Thus, modern cytology was called cell physiology.

Significant advances in the study of cells occurred in the early 19th century, with the discovery and description of cell nucleus. Based on these studies, it was created cell theory, which became greatest event in biology of the 19th century. It was this theory that served as the foundation for the development of embryology, physiology, and the theory of evolution.

The most important part of all cells is the nucleus, which stores and reproduces genetic information and regulates metabolic processes in the cell.

All cells are divided into two groups:

Prokaryotes are cells without a nucleus

Eukaryotes - cells containing nuclei

Studying a living cell, scientists drew attention to the existence of two main types of its nutrition, which made it possible to divide all organisms into two types:

Autotrophic - they produce what they need on their own. nutrients

· Heterotrophic - cannot do without organic food.

Later, such important factors as the ability of organisms to synthesize necessary substances (vitamins, hormones), provide themselves with energy, dependence on the ecological environment, etc. were clarified. Thus, the complex and differentiated nature of the connections indicates the need for a systematic approach to the study of life at the ontogenetic level .

3. Ontogenetic level. Multicellular organisms. This level arose as a result of the formation of living organisms. The basic unit of life is the individual, and the elementary phenomenon is ontogenesis. Physiology studies the functioning and development of multicellular living organisms. This science examines the mechanisms of action various functions living organism, their relationship with each other, regulation and adaptation to external environment, origin and formation in the process of evolution and individual development individuals. In essence, this is the process of ontogenesis - the development of the organism from birth to death. At the same time, growth, movement of individual structures, differentiation and complication of the organism occur.

All multicellular organisms are composed of organs and tissues. Tissues are a group of physically united cells and intercellular substances to perform specific functions. Their study is the subject of histology.

Organs are relatively large functional units that combine various fabrics into certain physiological complexes. In turn, organs are part of larger units - body systems. Among them are the nervous, digestive, cardiovascular, respiratory and other systems. Internal organs Only animals have it.

4. Population-biocenotic level. This is a supraorganismal level of life, the basic unit of which is the population. In contrast to a population, a species is a collection of individuals that are similar in structure and physiological properties having common origin, can freely interbreed and produce fertile offspring. A species exists only through populations representing genetically open systems. Population biology is the study of populations.

The term “population” was introduced by one of the founders of genetics, V. Johansen, who so called a genetically heterogeneous collection of organisms. Later the population began to be considered whole system, continuously interacting with the environment. It is the populations that are real systems through which species of living organisms exist.

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

Populations capable of independent existence and transformations are combined into the aggregate of the next supraorganismal level - biocenoses. Biocenosis is a set of populations living in a certain territory.

A biocenosis is a system closed to foreign populations; for its constituent populations it is an open system.

5. Biogeocetonic level. Biogeocenosis is a stable system that can exist for a long time. Equilibrium in a living system is dynamic, i.e. represents constant movement around a certain stability point. For its stable functioning it is necessary to have feedback between its control and execution subsystems. This way of maintaining a dynamic balance between various elements 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 an environmental disaster.

Biogeocenosis is a holistic self-regulating system, which distinguishes several types of subsystems. Primary systems - producers that directly process inanimate matter; consumers - a secondary level at which matter and energy are obtained through the use of producers; then come second-order consumers. There are also scavengers and decomposers.

The cycle of substances passes through these levels in the biogeocenosis: life participates in the use, processing and restoration various structures. In biogeocenosis - unidirectional energy flow. This makes it an open system, continuously connected with neighboring biogeocenoses.

Self-regulation of biogeocenls is more successful the more diverse the number of its constituent elements is. The stability of biogeocenoses also depends on the diversity of its components. The loss of one or more components can lead to an irreversible imbalance and the death of it as an integral system.

6. Biosphere level. This highest level organization of life, covering all phenomena of life on our planet. The biosphere is living matter planets and the environment transformed by it. Biological metabolism is a factor that unites all other levels of life organization into one biosphere. At this level, the circulation of substances and the transformation of energy occur, associated with the vital activity of all living organisms living on Earth. Thus, the biosphere is one ecological system. Studying the functioning of this system, its structure and functions - the most important task biology at this level of life. Ecology, biocenology and biogeochemistry study these problems.

The development of the doctrine of the biosphere is inextricably linked with the name of the outstanding Russian scientist V.I. Vernadsky. It was he who managed to prove the connection between the organic world of our planet, acting as a single indivisible whole, with geological processes on the ground. Vernadsky discovered and studied the biogeochemical functions of living matter.