Processes studied at the molecular genetic level of life. Definition of life

All Live nature is a collection of biological systems different levels organization and various subordination.
The level of organization of living matter is understood as the functional place that a given biological structure occupies in common system organization of nature.

Level of organization of living matter is a set of quantitative and qualitative parameters of a certain biological system (cell, organism, population, etc.), which determine the conditions and boundaries of its existence.

There are several levels of organization of living systems, which reflect the subordination and hierarchy of the structural organization of life.

Molecular (molecular genetic) level represented by individual biopolymers (DNA, RNA, proteins, lipids, carbohydrates and other compounds); At this level of life, phenomena related to changes (mutations) and reproduction of genetic material and metabolism are studied. This is what science does - molecular biology.
Cellularlevel- the level at which life exists in the form of a cell - the structural and functional unit of life, is studied by cytology. At this level, processes such as metabolism and energy, information exchange, reproduction, photosynthesis, nerve impulse transmission and many others are studied.

The cell is the structural unit of all living things.

Tissue level studies histology.

Tissue is a collection of intercellular substance and cells similar in structure, origin and functions.

Organlevel. The organ includes several tissues.
Organismallevel- the independent existence of an individual - a unicellular or multicellular organism is studied, for example, physiology and autecology (ecology of individuals). An individual as an integral organism represents an elementary unit of life. Life in nature does not exist in any other form.

An organism is a real carrier of life, characterized by all its properties.

Population-specieslevel- level, which is represented by a group of individuals of the same species - a population; It is in the population that elementary evolutionary processes occur (accumulation, manifestation and selection of mutations). This level of organization is studied by such sciences as deecology (or population ecology) and evolutionary science.

A population is a collection of individuals of the same species that exist for a long time in a certain territory, interbreed freely and are relatively isolated from other individuals of the same species.

Biogeocenoticlevel- represented by communities (ecosystems) consisting of different populations and their habitats. This level of organization is studied by biocenology or synecology (ecology of communities).

Biogeocenosis is a collection of all species with varying complexity of organization and all factors of their habitat.

Biospherelevel- a level representing the totality of all biogeocenoses. In the biosphere there is a circulation of substances and the transformation of energy with the participation of organisms.

Evolution theory

Guidelines for laboratory exercises

for students of the Faculty of Agronomy

Miasskoe

Methodological instructions for performing laboratory classes are intended for students of the Faculty of Agronomy studying in the direction of 03/35/04 “Agronomy”, 03/35/07 “Technology of production and processing of agricultural products” on full-time and part-time courses with the aim of mastering the discipline “Theory of Evolution”.

Compiled by:

Matveeva E. Yu. – Ph.D. biol. Sciences (Institute of Agroecology - branch of FSBEI HE SUSU)

Structure and evaluation of the laboratory report……………….4

Properties and levels of organization of living matter………………….………….5

Evolution modeling…………………………………………………………….…………24

Evolutionary views of scientists………………………………….…………..26

Evolutionary theories J. B. Lamarck and C. Darwin………….…………….79

The main stages of development of the organic world……………….………………….90

Evolution of organisms as adaptationogenesis…………………………………108

Genetic basis of evolution……………………………………………..118

Factors of macroevolution……………………………………………………..128

Structure and evaluation of a laboratory report

The report on the laboratory lesson is used to assess the quality of the student’s mastery of educational program on discipline topics. The report is assessed as “passed” or “failed” (Table 1).

Table 1 – Report evaluation criteria

1 Topic of laboratory lesson

2 Completed tasks

3 Answers to security questions

Properties and levels of organization of living matter

Introduction

The organic world is a single whole, because it is a system of interconnected parts (in which the existence of some organisms depends on others), and at the same time discrete (consists of individual units - organisms, or individuals). Each living organism is also discrete, since 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 is composed of organelles but functions as a single unit. Hereditary information is carried out by genes, but none of the genes outside the entire set determines the development of a trait, etc.

Associated with the discreteness of life are various levels of organization of the organic world, which can be defined as discrete states of biological systems characterized by the properties of subordination, interconnectedness, and specific patterns. At the same time, each new level is distinguished by the special properties and patterns of the previous, lower level, since each 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 macrobiological system. At all levels of life, such attributes as discreteness and integrity are manifested, structural organization, exchange of matter, energy and information. The existence of life at all levels is prepared and determined by the structure of the lower level. The nature of the cellular level of organization is determined by the molecular and subcellular levels, organismic - by cellular, tissue, etc.

The structural levels of the organization of life are extremely diverse, but of all their diversity, the main ones are molecular genetic, ontogenetic, population-species and biosphere.

Molecular genetic level of life

For a normal life cycle, any organism requires a certain set of basic chemical elements. This set includes three groups of elements: macroelements, microelements and ultramicroelements.

The macroelements, which are called organogens, include four elements - carbon, oxygen, nitrogen and hydrogen. These elements make up the bulk of the organic matter of the cell (95–99%).

Macroelements also include potassium, sodium, calcium, magnesium, phosphorus, sulfur, chlorine and iron, the amount of which in the cell ranges from tenths to hundredths of a percent (1.9%).

Microelements are those elements that are present in living tissues in very small concentrations (0.001% to 0.000001%). This group consists of: manganese, iron, cobalt, copper, zinc, vanadium, boron, aluminum, silicon, molybdenum, iodine (.01%). They are part of biologically active substances - enzymes, vitamins, hormones.

Ultramicroelements are elements whose content in the cell does not exceed 0.000001%. This group consists of gold, uranium, radium, etc.

Thus, for normal functioning, a living cell needs 24 natural chemical elements, each of which has its own purpose; a total of 80 elements were found in cells.

Main organic substances cells are carbohydrates, lipids, amino acids, proteins, nucleic acids.

Carbohydrates include carbon compounds, which are divided into three groups of saccharides. Carbohydrates play an important role in the life of organisms: they are a component of the connective tissue of vertebrates, provide blood clotting, repair damaged tissues, form the walls of plants, bacteria, fungi, etc.

Lipids are various groups of water-repellent compounds; most lipids are esters of trihydric alcohol, glycerol and fatty acids, i.e. fats. Fats serve as a source of energy and water for the cell and the body as a whole; in addition, they participate in the thermoregulation of the body, creating a heat-insulating fat layer. Other types of lipids perform a protective function, being part of the exoskeleton of insects, covering feathers and wool.

Amino acids are compounds that contain a carboxyl group and an amino group. In total, more than 170 amino acids occur in nature. In cells they function as building materials for proteins. However, only 20 amino acids are found in proteins. Most amino acids are produced by plants and microorganisms. However, some animals lack some of the enzymes needed to synthesize amino acids, so they must obtain some amino acids from their diet. Such acids are called essential. For humans, eight acids are essential, and four more are only conditionally replaceable. The most important property amino acids is their ability to enter into a half-condensation reaction with the formation of polymer chains - polypeptides and proteins.

Proteins are the main building material for cells. They are complex biopolymers, the elements of which are monomer chains consisting of various combinations of twenty amino acids. There are more proteins in a living cell than other organic compounds (up to 50% of dry weight).

Most proteins function as catalysts (enzymes). Proteins also 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 whose function is to coordinate movement. There are proteins - antibodies, the function of which is to protect the body from viruses, bacteria, etc. Activity nervous system depends on proteins with the help of which information from the environment is collected and stored. Proteins called hormones control cell growth and activity.

The molecular basis of metabolism in cells is quite well studied today.

There are three main types of metabolism (metabolism):

Catabolism, or dissimilation, is the process of breakdown of complex organic compounds, accompanied by the release of chemical energy upon rupture chemical bonds. This energy is stored in the phosphate bonds of ATP (adenosine triphosphoric acid).

Amphobolism is the process of formation during catabolism small molecules, which then take part in the construction of more complex molecules.

Anabolism, or assimilation, is a branched system of processes of biosynthesis of complex molecules with the consumption of ATP energy.

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 located on the chromosome under the influence external factors. Factors that cause mutation (mutagens) are: radiation, toxic chemical compounds, as well as viruses. With this mechanism, the order of genes on the chromosome does not change.

Another mechanism of variability is gene recombination. This is the creation of new combinations of genes located on a specific chromosome. In this case, the genes themselves do not change, but move from one part of the chromosome to another, or genes are exchanged between two chromosomes. This process occurs during sexual reproduction in higher organisms. In this case, there is no change in the total volume of genetic information; it remains unchanged. This mechanism explains why children are only partially similar to their parents - they inherit traits from both parents, which are combined at random.

Another mechanism of variability was discovered only in the 1950s. This is a non-classical recombination of genes, in which there is a general increase in the volume of genetic information due to the inclusion of new ones in the cell genome genetic elements. Most often, these 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 medications, addiction to these medications occurs and they stop working. The pathogenic bacteria against which our medicine acts bind to plasmids, which make these bacteria resistant to the medicine, and the bacteria 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 goal of which is to create new forms of organisms with specified properties. In this case, new combinations of genes that do not exist in nature are constructed using genetic and biochemical methods. To do this, DNA is modified, which is encoded to produce a protein with the desired properties. All modern biotechnologies are based on this.

Ontogenetic level

This level arose as a result of the formation of living organisms. The basic unit of life at this level is the individual, and the elementary phenomenon is ontogenesis. A biological individual can be either a unicellular or a multicellular organism, but in any case it represents an integral, self-reproducing system.

Ontogenesis is the process of individual development of an organism from birth through successive morphological, physiological and biochemical changes until death, the process of realizing hereditary information. At present, a unified theory of ontogenesis has not been created, since the causes and factors determining the individual development of the organism have not been established.

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, 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 living cells is called cytology. It studies the structure of cells, their functioning as elementary living systems, studies adaptation to environmental conditions, etc. Cytology also studies the characteristics 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 discovery of the existence of cells and their research occurred in late XVII century when the first microscope was invented. The cell was first described by the English scientist Robert Hooke back in 1665, when he was examining a piece of cork. Since his microscope was not very advanced, what he saw were actually walls of dead cells. It took almost two hundred years for biologists to understand that the main role is played not by the walls of the cell, but by its internal contents. Among the predecessors of the cell theory, one should also name Anthony van Leeuwenhoek (1632–1723), who proved that the tissues of many plant organisms are built from cells.

T. Schwann and M. Schleiden created the cell theory in 1838, which became greatest event in biology of the 19th century. It was this theory that provided decisive evidence of the unity of all living nature and served as the foundation for the development of embryology, histology, physiology, the theory of evolution, as well as the understanding of the individual development of organisms. Cytology has received a powerful impetus since the creation of genetics and molecular biology. After this, new cell components were discovered - 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 (body cells). Somatic cells differ in structure and function - there are nerve, bone, muscle, and secretory cells. Cell sizes can vary from 0.1 microns (some bacteria) to 155 mm (an ostrich egg in a shell). In a living organism there are billions of different cells (up to 1015), the shape of which can be the most bizarre (spider, star, snowflake, etc.).

All cells consist of three main parts: the plasma membrane, which controls the passage of substances from the environment into the cell and back; cytoplasm with a diverse structure and the cell nucleus, which contains genetic information. In addition, all animal and some plant cells contain centrioles, cylindrical structures that form the cell's centers. Plant cells also have a cell wall (shell) and plastids - specialized cell structures that often contain pigment, which determines the color of the cell.

Cells grow and reproduce by dividing into two daughter cells. There are two ways of cell division. Mitosis is a division of the cell nucleus in which two daughter nuclei are formed with a set of chromosomes identical to the set of the parent cell. In this case, a complete set of chromosomes carrying genetic information is transmitted to the daughter cells. After divergence, the daughter strands of DNA turn into chromosomes, forming structures characteristic of a given organism. This method of reproduction is characteristic of all cells except sex cells.

Meiosis is the division of the cell nucleus to form four daughter nuclei, each of which contains half as many chromosomes as the original nucleus. This mechanism of cell division occurs in nature only in preparation for sexual reproduction, during the formation of germ cells (gametes). When gametes fuse during fertilization, a diploid set of chromosomes is obtained again. This method of reproduction is characteristic only of germ cells.

Multicellular organisms also develop from one cell - an egg, but during its division the cells are modified, which leads to the appearance of many different cells - muscle, nerve, blood, etc. Different cells synthesize different proteins. However, each cell of a multicellular organism has complete genetic information to build all the proteins needed for that organism.

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

Prokaryotes are cells without a nucleus. In them, DNA molecules are not surrounded by a nuclear membrane and are not organized into chromosomes. These include bacteria.

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

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 organisms - they do not need organic food and can live by assimilation of carbon dioxide (bacteria) or photosynthesis (plants), i.e. they themselves produce the nutrients they need;

Heterotrophic organisms are all organisms that cannot survive without organic food.

Multicellular organisms. All multicellular organisms are divided into three kingdoms: fungi, plants and animals. Their vital activity, as well as the work of individual parts of multicellular organisms, is studied by physiology. This science examines the mechanisms of action of various functions of a living organism, their relationship with each other, regulation and adaptation to the external environment, origin and formation in the process of evolution and individual development of the individual. In fact, this is the process of ontogenesis - the development of the organism from birth to death, during which growth, movement of individual structures, differentiation and complication of the organism occur. This process is described on the basis of the famous biogenetic law formulated by Ernst Haeckel (1834–1919), the author of the term “ontogenesis.”

The biogenetic law states that ontogeny in a brief form repeats phylogeny, that is, an individual organism in its individual development in a short form goes through all the stages of development of its species. Thus, ontogeny represents the implementation of hereditary information encoded in the germ cell, as well as a check of 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 united cells and intercellular substances that are similar in structure and function. Their study is the subject of histology. Tissues can be formed from either the same or different specialized cells. For example, in animals, squamous epithelium is built from identical cells, and muscle, nervous, and connective tissue is built from different cells.

Organs are relatively large functional parts of the body that perform a specific function, consisting of cells of various types and controlled common mechanism body. In turn, organs are part of larger units - body systems. Among them are the nervous, digestive, cardiovascular, respiratory and other systems. Each of these systems includes operating bodies and a hierarchy of control mechanisms.

A living organism itself can be represented as a complex of physiological systems that ensure its homeostasis and adaptation. It is formed as a result of the interaction of the genotype (the set of genes of one organism) with the phenotype (a complex external signs organism formed during its individual development). Thus, the body is a stable system of internal organs and tissues existing in the external environment. However, since general theory Ontogenesis has not yet been created; many processes occurring during the development of an organism have not yet received their full explanation.

IV. Biogenetic methods to increase life expectancy

IV. Actions of orderlies in case of threat to the life of a patient or doctor

PS. This formula is applied in the case when the inflation rate is stable, and the inflation measurement period has a regular frequency.

THE EYE AND THE SPIRIT" ("L"Œil et l"esprit". Paris, 1964) - the last work of Merleau-Ponty published during his lifetime

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 of 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 of external factors. Factors that cause 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.

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 a science that studies a 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, the formation of their special functions and the development of specific cellular structures . Thus, modern cytology was called cell physiology.

Significant advances in the study of cells occurred at the beginning of the 19th century, with the discovery and description of the cell nucleus. Based on these studies, the cell theory was created, which became the 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 - produces the nutrients they need on their own

· 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 ecological environment etc. Thus, the complex and differentiated nature of the connections indicates the need systematic approach to the study of life and 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 of various functions of a living organism, their relationship with each other, regulation and adaptation to the external environment, origin and formation in the process of evolution and individual development of the individual. 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 unite various tissues 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. Only animals have internal organs.

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, have a common origin, and 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 gave this name to a genetically heterogeneous collection of organisms. Later, the population began to be considered an integral system, continuously interacting with environment. Populations are the real systems through which species of living organisms exist.

Populations are genetically open systems, since the isolation of populations is not absolute and periodically it is not possible to exchange 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 transformation are united in the aggregate of the next supraorganism 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 a constant movement around a certain point of stability. For its stable functioning, it is necessary to have feedback connections between its control and execution subsystems. This method of maintaining a dynamic balance between various elements of 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 an integral self-regulating system in which several types of subsystems are distinguished. Primary systems are producers that directly process nonliving 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 of various structures. In biogeocenosis there is a 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 a single ecological system. Studying the functioning of this system, its structure and functions is the most important task of 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, and geological processes on Earth. Vernadsky discovered and studied the biogeochemical functions of living matter.

Thanks to the biogenic migration of atoms, living matter performs its geochemical functions. Modern science identifies five geochemical functions performed by living matter.

1. The concentration function is expressed in the accumulation of certain chemical elements inside living organisms due to their activities. The result of this was the emergence of mineral reserves.

2. The transport function is closely related to the first function, since living organisms transport the chemical elements they need, which then accumulate in their habitats.

3. Energy function provides energy flows that penetrate the biosphere, which makes it possible to carry out all the biogeochemical functions of living matter.

4. Destructive function - the function of destruction and processing of organic remains; during this process, substances accumulated by organisms return to natural cycles, the circulation of substances in nature occurs.

5. Medium-forming function - transformation of the environment under the influence of living matter. The entire modern appearance of the Earth - the composition of the atmosphere, hydrosphere, upper layer of the lithosphere; most of the minerals; climate is the result of the action of Life.

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 of external factors. Factors that cause mutation are: radiation, toxic chemical compounds, 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 a science that studies a 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, the formation of their special functions and the development of specific cellular structures . Thus, modern cytology was called cell physiology.

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 - produces the nutrients they need on their own

· 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 of various functions of a living organism, their relationship with each other, regulation and adaptation to the external environment, origin and formation in the process of evolution and individual development of the individual. 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.

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, have a common origin, and 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 gave this name to a genetically heterogeneous collection of organisms. Later, the population began to be considered an integral system that continuously interacts with the environment. Populations are the real systems through which species of living organisms exist.

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

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 a constant movement around a certain point of stability. For its stable functioning, it is necessary to have feedback connections between its control and execution subsystems. This method of maintaining a dynamic balance between various elements of 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.

6. Biosphere level. This is the highest level of organization of life, covering all phenomena of life on our planet. The biosphere is the living matter of the planet 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 a single ecological system. Studying the functioning of this system, its structure and functions is the most important task of biology at this level of life. Ecology, biocenology and biogeochemistry study these problems.

There are such levels of organization of living matter - levels of biological organization: molecular, cellular, tissue, organ, organismal, 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, transmission 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 living things, a functional unit, a unit of development. This level is studied by cytology, cytochemistry, cytogenetics, and 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, and embryology study this level.

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

Population-species level- this is the level of aggregates 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, types of relationships between organisms and populations in the ecosystem are studied, population size, population dynamics, population density, ecosystem productivity, succession. This level studies ecology.

Also distinguished biosphere level of organization living matter. The biosphere is a gigantic ecosystem that occupies part of the geographical envelope of the Earth. This is a mega ecosystem. In the biosphere there is a circulation of substances and chemical elements, as well as the transformation 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, and the ability to adapt to it and its changes. During the metabolic process, the molecules that make up the cells are broken down and synthesized; formation, destruction and renewal of cellular structures and intercellular substance. Metabolism is based on the interrelated processes of assimilation (anabolism) and dissimilation (catabolism). Assimilation - 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 deposition of synthesized substances). Dissimilation is the process of breakdown (anaerobic or aerobic) of complex organic compounds, which occurs with the release of energy necessary for the functioning of the body. 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 that are strictly ordered in time and space. The coordinated occurrence of a large number of reactions in a small volume is achieved through the ordered distribution of individual metabolic units in the cell (the principle of compartmentalization). Metabolic processes are regulated with the help of biocatalysts - special enzyme proteins. Each enzyme has the substrate specificity to catalyze the conversion of only one substrate. This specificity is based on a kind of “recognition” of the substrate by the enzyme. Enzymatic catalysis differs from non-biological catalysis 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 during participation in reactions. Another characteristic difference between enzymes and non-biological catalysts is that enzymes are capable of accelerating reactions under normal conditions (atmospheric pressure, body temperature, etc.). All living organisms can be divided into two groups - autotrophs and heterotrophs, differing in the sources of energy and necessary substances for their life. Autotrophs are organisms that synthesize from inorganic substances organic compounds Using the energy of sunlight (photosynthetics - green plants, algae, some bacteria) or energy obtained from the oxidation of an inorganic substrate (chemosynthetics - sulfur, iron bacteria and some others), Autotrophic organisms are able to synthesize all 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 life. biogeochemical cycles in the cycle of substances on Earth. Heterotrophs (all animals, fungi, most bacteria, some non-chlorophyll plants) are organisms that require for their existence ready-made organic substances, which, when supplied as food, serve as both a source of energy and a necessary “building material”. A characteristic feature of heterotrophs is the presence of amphibolism, 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 one’s own kind, self-reproduction) is 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 losses caused by the natural death of individuals, and thus maintains the preservation of the species over generations of individuals. In the process of evolution of living organisms, the evolution of methods of reproduction occurred. Therefore, in the numerous and diverse species of living organisms that currently exist, we find different shapes reproduction. Many species of organisms combine several methods of reproduction. It is necessary to distinguish two fundamentally different types of reproduction of organisms - asexual (the 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 organisms) of the maternal organism. In all forms of asexual reproduction, offspring have a genotype (set of genes) identical to the maternal one. Consequently, all the offspring of one maternal organism turn out to be genetically homogeneous and the daughter individuals have the same set of characteristics. In sexual reproduction, a new individual develops from a zygote, which is formed by the fusion of two specialized germ cells (the process of fertilization) produced by two parent organisms. The nucleus in the zygote contains a hybrid set of chromosomes, formed as a result of combining sets of chromosomes of fused gamete nuclei. In the nucleus of the zygote, a new combination of hereditary inclinations (genes), introduced equally by both parents, is thus created. And the daughter organism developing from the zygote will have a new combination of characteristics. In other words, during sexual reproduction, a combinative form of hereditary variability of organisms occurs, which ensures the adaptation of species to changing environmental conditions and represents an essential factor in evolution. This is a significant advantage of sexual reproduction compared to asexual reproduction. The ability of living organisms to reproduce themselves is based on the unique property of nucleic acids for reproduction 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 (cell self-reproduction) 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 (in RNA for some viruses). Genes encode information about the structure of synthesized proteins, enzymatic and structural. The genetic code is a system for “recording” information about the sequence of amino acids in synthesized proteins using the sequence of nucleotides in the DNA molecule. The set of all genes of an organism is called a genotype, and the set of characteristics is called a phenotype. The phenotype depends both on the genotype and on internal and external environmental factors that affect gene activity 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. Thanks to heredity, traits are passed on from generation to generation that ensure the adaptation of organisms to their environment. If during the reproduction of organisms only the continuity of existing signs and properties were 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 the conditions of their environment. There is variability in the diversity of organisms belonging to the same species. Variability can occur in individual organisms during their individual development or within a group of organisms over a series of generations during reproduction. There are two main forms of variability, differing in the mechanisms of occurrence, the nature of changes 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 phenotype. Genotypic variability may be based on mutations (mutational variability) or new combinations of genes that arise during the process of fertilization during sexual reproduction. In the mutational form, changes are associated primarily with errors during the replication of nucleic acids. Thus, new genes appear that carry new genetic information; new signs appear. And if newly emerging characters are useful to the organism in specific conditions, then they are “picked 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 preconditions for positive evolution are created. With non-hereditary (modifying) variability, changes in the phenotype occur under the influence of environmental factors and are not associated with changes in the genotype. Modifications (changes in characteristics during modification variability) occur within the limits of the reaction norm, which is under the control of the genotype. Modifications are not passed on to subsequent generations. The significance of modification variability is that it ensures the organism's adaptability to environmental factors during its life.

Individual development of organisms

All living organisms are characterized by a process of individual development - ontogenesis. Traditionally, ontogeny 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 the zygote to the natural death of the 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 a “genetic program” (embedded in the genes of the chromosomes of the zygote) and is carried out under specific environmental conditions, which significantly influence the process of implementation of genetic information during the individual existence of an individual. At the early stages of individual development, intensive growth occurs (increase in mass and size), caused by the reproduction of molecules, cells and other structures, and differentiation, i.e. the emergence 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 body. Studying the role of these factors in the process of individual development of animals and humans is of great practical importance, increasing as the anthropogenic impact on nature intensifies. In various fields of biology, medicine, veterinary medicine and other sciences, research is widely carried out to study the processes of normal and pathological development of organisms and to clarify the patterns of ontogenesis.

Irritability

An integral property of organisms and all living systems is irritability - the ability to perceive external or internal stimuli (impacts) and respond adequately to them. In organisms, irritability is accompanied by a complex of changes, expressed in changes in metabolism, electric potential on cell membranes, physical and chemical 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 generalizing rule for 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 V 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 information transition DNA → DNA. In nature, there are also transitions RNA → RNA and RNA → DNA (for example, in some viruses), as well as changes conformation proteins transferred from molecule to molecule.

Universal methods of transmitting biological information

In living organisms there are three types of heterogeneous, that is, consisting of different polymer monomers - DNA, RNA and protein. Information can be transferred between them 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 - found as an exception, in viruses and at mobile genome elements or under biological conditions experiment;

Unknown - not found.

DNA replication (DNA → DNA)

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

Transcription (DNA → RNA)

Transcription is a biological process as a result of which the information contained in a section of DNA is copied onto the 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 broadcast process. IN prokaryotic In cells, the processes of transcription and translation are not spatially separated, and these processes are coupled. IN eukaryotic cell site of transcription cell nucleus separated from the broadcast location ( 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 occurs in the “reverse” direction relative to transcription.

The idea of reverse transcription was very unpopular at first because 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 phages and virulent ones are capable of transduction; the latter, however, destroy the bacterial population, so transduction with their help has no effect. of great importance neither in nature nor during research.

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

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

Presence of a selective marker

Availability of convenient restriction sites

Bacterial plasmids most often act as vectors.