Natalya Sergeevna Kurbatova, E. A. Kozlova
General biology
1. History of the development of cell theory
The prerequisites for the creation of the cell theory were the invention and improvement of the microscope and the discovery of cells (1665, R. Hooke - when studying a cut of the bark of a cork tree, elderberry, etc.). The works of famous microscopists: M. Malpighi, N. Gru, A. van Leeuwenhoek - made it possible to see the cells of plant organisms. A. van Leeuwenhoek discovered unicellular organisms in water. The cell nucleus was studied first. R. Brown described the nucleus of a plant cell. Ya. E. Purkine introduced the concept of protoplasm - liquid gelatinous cellular contents.
The German botanist M. Schleiden was the first to come to the conclusion that every cell has a nucleus. The founder of CT is the German biologist T. Schwann (together with M. Schleiden), who in 1839 published the work “Microscopic studies on the correspondence in the structure and growth of animals and plants”. His provisions:
1) cell - the main structural unit of all living organisms (both animals and plants);
2) if there is a nucleus in any formation visible under a microscope, then it can be considered a cell;
3) the process of formation of new cells determines the growth, development, differentiation of plant and animal cells.
Additions to the cellular theory were made by the German scientist R. Virchow, who in 1858 published his work "Cellular Pathology". He proved that daughter cells are formed by division of mother cells: each cell from a cell. At the end of the XIX century. mitochondria, the Golgi complex, and plastids were found in plant cells. Chromosomes were detected after dividing cells were stained with special dyes. Modern provisions of CT
1. Cell - the basic unit of the structure and development of all living organisms, is the smallest structural unit of the living.
2. Cells of all organisms (both unicellular and multicellular) are similar in chemical composition, structure, basic manifestations of metabolism and vital activity.
3. Reproduction of cells occurs by their division (each new cell is formed during the division of the mother cell); in complex multicellular organisms, cells have different shapes and are specialized according to their functions. Similar cells form tissues; tissues consist of organs that form organ systems, they are closely interconnected and subject to nervous and humoral mechanisms of regulation (in higher organisms).
Significance of cell theory
It became clear that the cell is the most important component of living organisms, their main morphophysiological component. The cell is the basis of a multicellular organism, the site of biochemical and physiological processes in the body. At the cellular level, all biological processes ultimately occur. The cell theory made it possible to conclude that the chemical composition of all cells is similar, general plan their structure, which confirms the phylogenetic unity of the entire living world.
2. Life. Properties of living matter
Life is a macromolecular open system, which is characterized by a hierarchical organization, the ability to self-reproduce, self-preservation and self-regulation, metabolism, a finely regulated flow of energy.
Properties of living structures:
1) self-updating. The basis of metabolism is balanced and clearly interconnected processes of assimilation (anabolism, synthesis, formation of new substances) and dissimilation (catabolism, decay);
2) self-reproduction. In this regard, living structures are constantly reproduced and updated, without losing their similarity with previous generations. Nucleic acids are capable of storing, transmitting and reproducing hereditary information, as well as realizing it through protein synthesis. Information stored on DNA is transferred to a protein molecule with the help of RNA molecules;
3) self-regulation. It is based on a set of flows of matter, energy and information through a living organism;
4) irritability. Associated with the transfer of information from the outside to any biological system and reflects the reaction of this system to an external stimulus. Thanks to irritability, living organisms are able to selectively react to environmental conditions and extract from it only what is necessary for their existence;
5) maintenance of homeostasis - the relative dynamic constancy of the internal environment of the body, the physico-chemical parameters of the existence of the system;
6) structural organization - orderliness, of a living system, found in the study - biogeocenoses;
7) adaptation - the ability of a living organism to constantly adapt to changing conditions of existence in the environment;
8) reproduction (reproduction). Since life exists in the form of separate living systems, and the existence of each such system is strictly limited in time, the maintenance of life on Earth is associated with the reproduction of living systems;
9) heredity. Provides continuity between generations of organisms (based on information flows). Due to heredity, traits are transmitted from generation to generation that provide adaptation to the environment;
10) variability - due to variability, a living system acquires features that were previously unusual for it. First of all, variability is associated with errors in reproduction: changes in the structure of nucleic acids lead to the emergence of new hereditary information;
11) individual development (the process of ontogenesis) - the embodiment of the initial genetic information embedded in the structure of DNA molecules into the working structures of the body. During this process, such a property as the ability to grow is manifested, which is expressed in an increase in body weight and size;
12) phylogenetic development. Based on progressive reproduction, heredity, struggle for existence and selection. As a result of evolution, a huge number of species appeared;
13) discreteness (discontinuity) and at the same time integrity. Life is represented by a collection of individual organisms, or individuals. Each organism, in turn, is also discrete, since it consists of a set of organs, tissues and cells.
3. Levels of life organization
Living nature is a holistic, but heterogeneous system, which is characterized by a hierarchical organization. A hierarchical system is such a system in which the parts (or elements of the whole) are arranged in order from highest to lowest.
Microsystems (pre-organism stage) include molecular (molecular-genetic) and subcellular levels.
Mesosystems (organismal stage) include cellular, tissue, organ, systemic, organismal (the organism as a whole), or ontogenetic, levels.
Macrosystems (supraorganismal stage) include population-species, biocenotic and global levels (the biosphere as a whole). At each level, one can single out an elementary unit and a phenomenon.
An elementary unit (EE) is a structure (or object), the regular changes of which (elementary phenomena, EE) make its contribution to the development of life at a given level.
Hierarchical levels:
1) molecular genetic level. EE is represented by the genome. A gene is a section of a DNA molecule (and in some viruses, an RNA molecule) that is responsible for the formation of any one trait;
2) subcellular level. EE is represented by some subcellular structure, i.e., an organelle that performs its inherent functions and contributes to the work of the cell as a whole;
3) cellular level. EE is a cell that is a self-functioning elementary
The textbook reflects state of the art science about the general laws of the origin and development of life on Earth. Part I of the textbook includes sections: "Introduction", "Life as a natural phenomenon", "Biology of the cell", "Reproduction of organisms", "Organization of hereditary material", "Patterns of inheritance" and "Variability".
The textbook is intended for university students studying in biological, medical and agricultural specialties.
properties of the living.
Living organisms, unlike bodies of inanimate nature, are characterized by a number of properties that are, in fact, attributes of life: orderliness and specificity of structure, integrity and discreteness, self-regulation and homeostasis, self-reproduction and self-healing, heredity and variability, metabolism and energy, growth and development, irritability, movement, self-regulation, specific relationship with the environment, aging and death, involvement in the continuous process of historical changes of the living (evolutionary process). These attributes of life are the objects of research by many independent biological sciences, the results of which are presented below in various sections of the textbook. However, some of them are reasonably classified as fundamental and require special consideration already at the beginning of the General Biology course.
Orderliness and specificity of the structure. Living organisms contain the same chemical elements as in the objects of wildlife. However, in the cells of living beings, they are in the form of not only inorganic, but also organic compounds. In addition, the form of existence of living things has very significant specific features, primarily complexity and orderliness, which distinguish both the molecular and supramolecular levels of organization. The creation of order is the most important property of the living. Order in space is accompanied by order in time.
Table of contents
INTRODUCTION 3
CHAPTER 1. LIFE AS A NATURAL PHENOMENA 9
1.1. Defining the Essence of Life 9
1.2. Substratum of life 10
1.3. Properties of living 11
1.4. Fundamental properties of life 12
1.5. Levels of organization of life 13
CHAPTER 2. CELL BIOLOGY 16
2.1. Cell is an elementary structural-functional and genetic unit of life 16
2.2. The main stages of development and the current state of cell theory 16
2.3. Structural organization of prokaryotic and eukaryotic cells 20
2.4. Surface cell apparatus 23
2.5. Cytoplasmic apparatus of the cell 30
2.5.1. Hyaloplasm 30
2.5.2. Cell organelles (organelles) 32
2.5.2.1. Membrane organelles (organelles) 34
2.5.2.2. Non-membrane organelles (organelles) 41
2.6. Nuclear apparatus of the cell 49
2.7. Cell life cycle 55
2.7.1. The concept of the cell life cycle 55
2.7.2. Interphase 56
2.7.2.1. Post-mitotic period 57
2.7.2.2. synthetic period. DNA self-duplication 57
2.7.2.3. Premitotic period 64
2.7.2.4. Mitotic period 65
2.7.2.5. Cell renewal in cell populations 69
2.7.2.6. Cell response to adverse effects 70
2.7.2.7. Cell dystrophy 70
CHAPTER 3. REPRODUCTION OF ORGANISMS 73
3.1. Reproduction is a universal property of the living. The evolution of reproduction 73
3.2. Asexual reproduction 73
3.2.1. Monocytogenic asexual reproduction 73
3.2.2. Polycytogenic asexual reproduction 75
3.3. Sexual reproduction 76
3.3.1. The evolution of sexual reproduction 77
3.3.2. Gametogenesis 82
3.3.3. Fertilization 91
3.4. Ways of interspecies exchange of biological information 92
3.5. Biological aspects of sexual dimorphism 95
CHAPTER 4. ORGANIZATION OF HEREDITARY MATERIAL 97
4.1. Subject, tasks and methods of genetics. Stages of development of genetics 97
4.2. Structural and functional levels of organization of hereditary material 100
4.3. Gene as a functional unit of heredity. Classification, properties and localization of genes 102
4.4. The main provisions of the chromosome theory of heredity 108
CHAPTER 5. PATTERNS OF INHERITANCE
5.1. Heredity as a property of ensuring material continuity between generations 110
5.2. Types and patterns of inheritance 111
5.3. Phenotype as a result of the realization of the genotype in certain environmental conditions 117
5.4. Molecular biological ideas about the structure and functioning of genes. Gene expression and its regulation 118
5.5. Interaction of genes 122
5.5.1. Interaction of allelic genes 122
5.5.2. Interaction of non-allelic genes 125
5.6. Pleiotropy 129
5.7. Multiple allelism 131
5.8. expressiveness and penetrance. Genocopies 133
5.9. Genetic engineering 134
CHAPTER 6. VARIABILITY 137
6.1. Variability as a universal property of the living 137
6.2. Modification variability, its adaptive nature, significance of ontogeny and evolution 138
6.3. Statistical Methods study of modification variability 143
6.4. Genotypic variability. Mechanisms and biological 146.
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A. A. Kamensky, E. A. Kriksunov, V. V. Pasechnik
Biology. General biology grades 10–11
Legend:
- tasks aimed at developing the skills to work with information presented in different forms;
- tasks aimed at developing communication skills;
- tasks aimed at developing general mental skills and abilities, the ability to independently plan ways to solve specific problems.
Introduction
You start studying school course"General Biology". This is the conditional name of the part of the school biology course, the task of which is to study common properties living, the laws of its existence and development. Reflecting wildlife and man as part of it, biology is becoming increasingly important in scientific and technological progress, becoming a productive force. Biology creates a new technology - biological, which should become the basis of a new industrial society. Biological knowledge should contribute to the formation of biological thinking and ecological culture in each member of society, without which further development human civilization is impossible.
§ one. Short story development biology
1. What does biology study?
2. What biological sciences do you know?
3. What biologists do you know?
Biology as a science. You know well that biology is the science of life. At present, it represents the totality of the sciences of living nature. Biology studies all manifestations of life: the structure, functions, development and origin of living organisms, their relationships in natural communities with the environment and with other living organisms.
Since man began to realize his difference from the animal world, he began to study the world around him. At first, his life depended on it. Primitive people it was necessary to know which living organisms could be eaten, used as medicines, for making clothes and dwellings, and which of them were poisonous or dangerous.
With the development of civilization, a person could afford such a luxury as doing science for educational purposes.
Studies of the culture of ancient peoples have shown that they had extensive knowledge about plants and animals and widely applied them in everyday life.
Charles Darwin (1809–1882)
Modern biology is a complex science, which is characterized by the interpenetration of ideas and methods of various biological disciplines, as well as other sciences - primarily physics, chemistry and mathematics.
The main directions of development of modern biology. Currently, three directions in biology can be conditionally distinguished.
First, this classical biology. It is represented by natural scientists who study the diversity of wildlife. They objectively observe and analyze everything that happens in wildlife, study living organisms and classify them. It is wrong to think that in classical biology all discoveries have already been made. In the second half of the XX century. not only many new species have been described, but also large taxa have been discovered, up to kingdoms (Pogonophores) and even superkingdoms (Archaebacteria, or Archaea). These discoveries forced scientists to take a fresh look at the entire history of the development of wildlife. For true natural scientists, nature is a value in itself. Every corner of our planet is unique for them. That is why they are always among those who acutely feel the danger to the nature around us and actively advocate for it.
The second direction is evolutionary biology. In the 19th century author of the theory natural selection Charles Darwin started as an ordinary naturalist: he collected, observed, described, traveled, revealing the secrets of wildlife. However, the main result of his work, which made him a famous scientist, was a theory explaining organic diversity.
Currently, the study of the evolution of living organisms is actively continuing. The synthesis of genetics and evolutionary theory led to the creation of the so-called synthetic theory of evolution. But even now there are still many unresolved questions, the answers to which evolutionary scientists are looking for.
Created at the beginning of the 20th century. our eminent biologist Alexander Ivanovich Oparin the first scientific theory of the origin of life was purely theoretical. Currently, experimental studies of this problem are being actively conducted, and thanks to the use of advanced physicochemical methods, important discoveries have already been made and new interesting results can be expected.
Alexander Ivanovich Oparin (1894–1980)
New discoveries made it possible to supplement the theory of anthropogenesis. But the transition from the animal world to man still remains one of the biggest mysteries of biology.
Third direction - physical and chemical biology, studying the structure of living objects using modern physical and chemical methods. This is a rapidly developing area of biology, important both in theoretical and practical terms. We can say with confidence that new discoveries await us in physical and chemical biology, which will allow us to solve many problems facing humanity.
The development of biology as a science. Modern biology is rooted in antiquity and is associated with the development of civilization in the Mediterranean countries. We know the names of many outstanding scientists who have contributed to the development of biology. Let's name just a few of them.
Hippocrates(460 - c. 370 BC) gave the first regarding detailed description structure of man and animals, pointed to the role of the environment and heredity in the occurrence of diseases. He is considered the founder of medicine.
Aristotle(384–322 BC) divided the world into four kingdoms: the inanimate world of earth, water and air; plant world; the animal world and the human world. He described many animals, laid the foundation for taxonomy. The four biological treatises he wrote contained almost all the information about animals known by that time. The merits of Aristotle are so great that he is considered the founder of zoology.
Theophrastus(372–287 BC) studied plants. He described more than 500 plant species, gave information about the structure and reproduction of many of them, introduced many botanical terms. He is considered the founder of botany.
Gaius Pliny the Elder(23-79) collected information about living organisms known by that time and wrote 37 volumes of the encyclopedia "Natural History". Almost until the Middle Ages, this encyclopedia was the main source of knowledge about nature.
Claudius Galen in his scientific research he widely used dissections of mammals. He was the first to make a comparative anatomical description of man and monkey. Studied central and peripheral nervous system. Historians of science consider him the last great biologist of antiquity.
Claudius Galen (c. 130 - c. 200)
Religion was the dominant ideology in the Middle Ages. Like other sciences, biology during this period had not yet emerged as an independent field and existed in the general mainstream of religious and philosophical views. And although the accumulation of knowledge about living organisms continued, one can speak of biology as a science at that time only conditionally.
The Renaissance is a transitional period from the culture of the Middle Ages to the culture of the New Age. The fundamental socio-economic transformations of that time were accompanied by new discoveries in science.
The most famous scientist of that era Leonardo da Vinci(1452–1519) made a certain contribution to the development of biology.
He studied the flight of birds, described many plants, methods of joining bones in joints, the activity of the heart and the visual function of the eye, and the similarity of human and animal bones.
In the second half of the XV century. natural sciences begin to develop rapidly. This was facilitated by geographical discoveries, which made it possible to significantly expand information about animals and plants. The rapid accumulation of scientific knowledge about living organisms led to the division of biology into separate sciences.
In the XVI-XVII centuries. Botany and zoology began to develop rapidly.
The invention of the microscope (early 17th century) made it possible to study the microscopic structure of plants and animals. Microscopically small living organisms, bacteria and protozoa, invisible to the naked eye, were discovered.
made a great contribution to the development of biology Carl Linnaeus, proposed a classification system for animals and plants.
Karl Maksimovich Baer(1792-1876) in his works formulated the main provisions of the theory of homologous organs and the law of germinal similarity, which laid the scientific foundations of embryology.
The textbook is devoted to general issues of modern biology. It provides basic information about the structure of living matter and general laws its functioning. The topics of the training course are outlined: the origin, evolution and diversity of life on Earth. The relationship between organisms and the conditions of their existence, the patterns of sustainability of ecological systems are shown.
For students educational institutions secondary vocational education.
TABLE OF CONTENTS
Preface 3
Introduction 4
Chapter 1
1.1. Chemical organization of the cell 8
1.1.1. Organic and inorganic substances that make up the cell 9
1.1.2. Functions of proteins and lipids in the cell 10
1.1.3. Nucleic acids and their role in the cell 13
1.2 Structure and functions of the cell 16
1.2.1. Cytoplasm and cell membrane 19
1.2.2. Cell organelles 21
1.2.3. Structural features of a plant cell 25
1.24. non-cellular life forms. Viruses 27
1.3. Metabolism and energy conversion in the cell 30
1.3.1. Plastic exchange 30
1.32. Energy exchange 35
1.3.3. Autotrophic and heterotrophic organisms 36
1.3.4. Photosynthesis. Chemosynthesis 36
1.4 Cell division 39
1.4.1. The life cycle of a cell. Mitotic cycle 40
1.4.2. Mitosis. Cytokinesis 41
1.4.3. Cell theory of the structure of organisms 44
1.5. Reproduction and individual development of organisms 44
1.5.1. Asexual and sexual reproduction 44
1.5.2 Meiosis 46
1.5.3. Sex cell formation and fertilization 49
1.5.4. Individual development of the organism 52
1.5.5. Embryonic stage of ontogeny 53
1.5.6. Post-embryonic development 57
Chapter 2. FUNDAMENTALS OF GENETICS AND BREEDING 59
2.1. Patterns of heredity 59
2.1.1. Laws of Mendel 59
2.1.2. T.Morgan's chromosome theory and linked inheritance 67
2.1.3. Sex genetics. Sex-linked inheritance 70
2.1.4. Interaction of genes 72
2.2. Patterns of variability 75
2.2.1. Hereditary, or genotypic, variability. 75
2.2.2. Modification, or non-hereditary, variability. 79
2.2.3. Human genetics 81
2.2.4. Genetics and medicine 85
2.2.5. Material bases of heredity and variability 87
2.2.6. Genetics and evolutionary theory. Population genetics 88
2.3. Breeding basics 92
2.3.1. Domestication - First stage selection 92
2.3.2. Centers of Diversity and Origins cultivated plants 95
2.3.3. Methods of modern selection 98
2.3.4. Plant breeding 102
2.3.5. Achievements in plant breeding 104
2.3.6. Animal breeding 106
2.3.7. Microbial breeding and biotechnology software
Chapter 3. EVOLUTIONARY DOCTRINE 114
3.1. general characteristics biology in the pre-Darwinian period 114
3.1.1. Evolutionary ideas in the ancient world. 114
3.1.2. The State of Natural Science in the Middle Ages and the Renaissance 116
3.1.3. Precursors of Darwinism 119
3.2. The evolutionary doctrine of Charles Darwin 124
3.3. Microevolution 129
3.3.1. View concept 129
3.3.2. Mechanisms of evolution. The doctrine of natural selection. 131
3.4. Natural selection in natural populations 136
3.4.1. The emergence of devices 139
3.4.2. Speciation 144
3.5. Macroevolution 149
3.5.1. Evidence for Evolution 150
3.5.2. The main directions of the evolutionary process 160
3.5.3. Development of the organic world 165
Chapter 4. ORIGIN AND INITIAL STAGES OF DEVELOPMENT OF LIFE ON EARTH
4.1. The diversity of the living world 181
4.2. Origin of life on Earth. 186
Chapter 5. THE ORIGIN OF MAN 193
5.1. Evidence of the relationship between humans and animals 193
5.2. The main stages of human evolution 197
5.3. Races of man 202
Chapter 6. FOUNDATIONS OF ECOLOGY 205
6.1. Ecology - the science of the relationship of organisms, species and communities with the environment 205
6.1.1. Abiotic factors 206
6.1.2. Biotic factors 209
6.2. Ecological systems 210
6.2.1. Changes in biogeocenoses 220
6.2.2. Ecosystem homeostasis 223
6.2.3. Interactions in the ecosystem. Symbiosis and its forms 226
Chapter 7. BIOSPHERE AND MAN 236
7.1. Teachings of V.I.Vernadsky about the biosphere. 236
7.2. Noosphere 241
7.3. Interrelation of nature and society. Anthropogenic impacts on natural biogeocenoses 242
Chapter 8. BIONICS 247
References 254
1. Cell theory (CT) Background of the cell theory
The prerequisites for the creation of the cell theory were the invention and improvement of the microscope and the discovery of cells (1665, R. Hooke - when studying a cut of the bark of a cork tree, elderberry, etc.). The works of famous microscopists: M. Malpighi, N. Gru, A. van Leeuwenhoek - made it possible to see the cells of plant organisms. A. van Leeuwenhoek discovered unicellular organisms in water. The cell nucleus was studied first. R. Brown described the nucleus of a plant cell. Ya. E. Purkine introduced the concept of protoplasm - liquid gelatinous cellular contents.
The German botanist M. Schleiden was the first to come to the conclusion that every cell has a nucleus. The founder of CT is the German biologist T. Schwann (together with M. Schleiden), who in 1839 published the work “Microscopic studies on the correspondence in the structure and growth of animals and plants”. His provisions:
1) cell - the main structural unit of all living organisms (both animals and plants);
2) if there is a nucleus in any formation visible under a microscope, then it can be considered a cell;
3) the process of formation of new cells determines the growth, development, differentiation of plant and animal cells. Additions to the cellular theory were made by the German scientist R. Virchow, who in 1858 published his work "Cellular Pathology". He proved that daughter cells are formed by division of mother cells: each cell from a cell. At the end of the XIX century. mitochondria, the Golgi complex, and plastids were found in plant cells. Chromosomes were detected after dividing cells were stained with special dyes. Modern provisions of CT
1. Cell - the basic unit of the structure and development of all living organisms, is the smallest structural unit of the living.
2. Cells of all organisms (both unicellular and multicellular) are similar in chemical composition, structure, basic manifestations of metabolism and vital activity.
3. Reproduction of cells occurs by their division (each new cell is formed during the division of the mother cell); in complex multicellular organisms, cells have different shapes and are specialized according to their functions. Similar cells form tissues; tissues consist of organs that form organ systems, they are closely interconnected and subject to nervous and humoral mechanisms of regulation (in higher organisms).
Significance of cell theory
It became clear that the cell is the most important component of living organisms, their main morphophysiological component. The cell is the basis of a multicellular organism, the site of biochemical and physiological processes in the body. At the cellular level, all biological processes ultimately occur. The cell theory made it possible to draw a conclusion about the similarity of the chemical composition of all cells, the general plan of their structure, which confirms the phylogenetic unity of the entire living world.
2. Definition of life at the present stage of development of science
It is quite difficult to give a complete and unambiguous definition of the concept of life, given the huge variety of its manifestations.
In most definitions of the concept of life, which were given by many scientists and thinkers over the centuries, the leading qualities that distinguish the living from the non-living were taken into account. For example, Aristotle said that life is “nutrition, growth and decrepitude” of the body; A. L. Lavoisier defined life as a "chemical function"; G. R. Treviranus believed that life is "a stable uniformity of processes with a difference in external influences." It is clear that such definitions could not satisfy scientists, since they did not reflect (and could not reflect) all the properties of living matter. In addition, observations indicate that the properties of the living are not exceptional and unique, as it seemed before, they are separately found among non-living objects. AI Oparin defined life as "a special, very complex form of the movement of matter." This definition reflects the qualitative originality of life, which cannot be reduced to simple chemical or physical laws. However, even in this case, the definition is of a general nature and does not reveal the specific peculiarity of this movement.
F. Engels in "Dialectics of Nature" wrote: "Life is a mode of existence of protein bodies, the essential point of which is the exchange of matter and energy with the environment."
For practical application, those definitions are useful, which contain the basic properties that are necessarily inherent in all living forms. Here is one of them: life is a macromolecular open system, which is characterized by a hierarchical organization, the ability to self-reproduce, self-preservation and self-regulation, metabolism, a finely regulated flow of energy. According to this definition, life is a core of order spreading in a less ordered universe.
Life exists in the form of open systems. This means that any living form is not closed only on itself, but constantly exchanges matter, energy and information with the environment.
3. Fundamental properties of living matter
These properties in a complex characterize any living system and life in general:
1) self-updating. Associated with the flow of matter and energy. The basis of metabolism is balanced and clearly interconnected processes of assimilation (anabolism, synthesis, formation of new substances) and dissimilation (catabolism, decay). As a result of assimilation, the body structures are updated and new parts (cells, tissues, parts of organs) are formed. Dissimilation determines the breakdown of organic compounds, provides the cell with plastic matter and energy. For the formation of a new one, a constant influx of necessary substances from the outside is needed, and in the process of life activity (and dissimilation, in particular), products are formed that need to be brought into the external environment;
2) self-reproduction. Provides continuity between successive generations of biological systems. This property is associated with the information flows embedded in the structure of nucleic acids. In this regard, living structures are constantly reproduced and updated, without losing their similarity with previous generations (despite the continuous renewal of matter). Nucleic acids are capable of storing, transmitting and reproducing hereditary information, as well as realizing it through protein synthesis. Information stored on DNA is transferred to a protein molecule with the help of RNA molecules;
3) self-regulation. It is based on a set of flows of matter, energy and information through a living organism;
4) irritability. Associated with the transfer of information from the outside to any biological system and reflects the reaction of this system to an external stimulus. Thanks to irritability, living organisms are able to selectively react to environmental conditions and extract from it only what is necessary for their existence. Irritability is associated with self-regulation of living systems according to the feedback principle: waste products are able to have an inhibitory or stimulating effect on those enzymes that were at the beginning of a long chain of chemical reactions;
5) maintenance of homeostasis (from Gr. homoios - "similar, identical" and stasis - "immobility, state") - the relative dynamic constancy of the internal environment of the body, the physicochemical parameters of the existence of the system;
6) structural organization - a certain orderliness, harmony of a living system. It is found in the study of not only individual living organisms, but also their aggregates in connection with the environment - biogeocenoses;
7) adaptation - the ability of a living organism to constantly adapt to changing conditions of existence in the environment. It is based on irritability and its characteristic adequate responses;
8) reproduction (reproduction). Since life exists in the form of separate (discrete) living systems (for example, cells), and the existence of each such system is strictly limited in time, the maintenance of life on Earth is associated with the reproduction of living systems. At the molecular level, reproduction is carried out due to matrix synthesis, new molecules are formed according to the program laid down in the structure (matrix) of pre-existing molecules;
9) heredity. Provides continuity between generations of organisms (based on information flows).
It is closely related to the autoreproduction of life at the molecular, subcellular and cellular levels. Due to heredity, traits are transmitted from generation to generation that provide adaptation to the environment;
10) variability is a property opposite to heredity. Due to variability, a living system acquires features that were previously unusual for it. First of all, variability is associated with errors in reproduction: changes in the structure of nucleic acids lead to the emergence of new hereditary information. New signs and properties appear. If they are useful for an organism in a given habitat, then they are picked up and fixed by natural selection. New forms and types are being created. Thus, variability creates prerequisites for speciation and evolution;
11) individual development (the process of ontogenesis) - the embodiment of the initial genetic information embedded in the structure of DNA molecules (i.e., in the genotype) into the working structures of the body. During this process, such a property as the ability to grow is manifested, which is expressed in an increase in body weight and size. This process is based on the reproduction of molecules, reproduction, growth and differentiation of cells and other structures, etc.;
12) phylogenetic development (its patterns were established by C. R. Darwin). Based on progressive reproduction, heredity, struggle for existence and selection. As a result of evolution, a huge number of species appeared. Progressive evolution has gone through a series of stages. These are pre-cellular, unicellular and multicellular organisms up to humans.
At the same time, human ontogeny repeats phylogenesis (i.e., individual development goes through the same stages as the evolutionary process);
13) discreteness (discontinuity) and at the same time integrity. Life is represented by a collection of individual organisms, or individuals. Each organism, in turn, is also discrete, since it consists of a set of organs, tissues and cells. Each cell consists of organelles, but at the same time is autonomous. Hereditary information is carried out by genes, but not a single gene alone can determine the development of a particular trait.
4. Levels of life organization
Living nature is a holistic, but heterogeneous system, which is characterized by a hierarchical organization. A hierarchical system is such a system in which the parts (or elements of the whole) are arranged in order from highest to lowest. The hierarchical principle of organization makes it possible to single out separate levels in living nature, which is very convenient when studying life as a complex natural phenomenon. There are three main stages of life: microsystems, mesosystems and macrosystems.
Microsystems (pre-organism stage) include molecular (molecular-genetic) and subcellular levels.
Mesosystems (organismal stage) include cellular, tissue, organ, systemic, organismal (the organism as a whole), or ontogenetic, levels.
Macrosystems (supraorganismal stage) include population-species, biocenotic and global levels (the biosphere as a whole). At each level, one can single out an elementary unit and a phenomenon.
An elementary unit (EE) is a structure (or object), the regular changes of which (elementary phenomena, EE) make its contribution to the development of life at a given level.
Hierarchical levels:
1) molecular genetic level. EE is represented by the genome. A gene is a section of a DNA molecule (and in some viruses, an RNA molecule) that is responsible for the formation of any one trait. The information embedded in nucleic acids is realized through the matrix synthesis of proteins;
2) subcellular level. EE is represented by some subcellular structure, i.e., an organelle that performs its inherent functions and contributes to the work of the cell as a whole;
3) cellular level. EE is a cell, which is an independently functioning elementary biological system. It is only at this level that the realization of genetic information and the processes of biosynthesis are possible. For unicellular organisms, this level coincides with the organism level. EE are the reactions of cellular metabolism, which form the basis of the flows of energy, information and matter;
4) tissue level. A set of cells with the same type of organization constitutes a tissue (EE). The level arose with the advent of multicellular organisms with more or less differentiated tissues. The tissue functions as a whole and has the properties of a living thing;
5) organ level. It is formed together with functioning cells belonging to different tissues (EE). Only four main tissues are part of the organs of multicellular organisms, six main tissues form the organs of plants;
6) organismic (ontogenetic) level. EE is an individual in its development from the moment of birth to the termination of its existence as a living system. EI are regular changes in the body in the process of individual development (ontogenesis). In the process of ontogenesis, under certain environmental conditions, the hereditary information is embodied in biological structures, i.e., on the basis of the genotype of an individual, its phenotype is formed;
7) population-species level. EE is a population, i.e. a set of individuals (organisms) of the same species inhabiting the same territory and interbreeding freely. The population has a gene pool, i.e., the totality of the genotypes of all individuals. The impact on the gene pool of elementary evolutionary factors (mutations, fluctuations in the number of individuals, natural selection) leads to evolutionarily significant changes (ER);
8) biocenotic (ecosystem) level. EE - biocenosis, i.e. a historically established stable community of populations different types, connected with each other and with the surrounding inanimate nature by the exchange of substances, energy and information (cycles), which are the EE;
9) biosphere (global) level. EE - the biosphere (the area of \u200b\u200bdistribution of life on Earth), that is, a single planetary complex of biogeocenoses, different in species composition and characteristics of the abiotic (non-living) part. Biogeocenoses determine all processes occurring in the biosphere;
10) nospheric level. This new concept was formulated by Academician V. I. Vernadsky. He founded the doctrine of the noosphere as the sphere of the mind. it component biosphere, which is changed due to human activity.
LECTURE № 2. Chemical composition of living systems. The biological role of proteins, polysaccharides, lipids and ATP
1. Overview of the chemical structure of the cell
All living systems contain chemical elements in various proportions and chemical compounds built from them, both organic and inorganic.
According to the quantitative content in the cell, all chemical elements are divided into 3 groups: macro-, micro- and ultramicroelements.
Macronutrients make up to 99% of the cell mass, of which up to 98% is accounted for by 4 elements: oxygen, nitrogen, hydrogen and carbon. In smaller quantities, cells contain potassium, sodium, magnesium, calcium, sulfur, phosphorus, and iron.
Trace elements are predominantly metal ions (cobalt, copper, zinc, etc.) and halogens (iodine, bromine, etc.). They are contained in amounts from 0.001% to 0.000001%.
Ultramicroelements. Their concentration is below 0.000001%. These include gold, mercury, selenium, etc.
A chemical compound is a substance in which the atoms of one or more chemical elements are connected to each other through chemical bonds. Chemical compounds are inorganic and organic. Inorganic include water and mineral salts. Organic compounds are compounds of carbon with other elements.
The main organic compounds of the cell are proteins, fats, carbohydrates and nucleic acids.
2. Biopolymers Proteins
These are polymers whose monomers are amino acids. They are mainly composed of carbon, hydrogen, oxygen and nitrogen. A protein molecule can have 4 levels of structural organization (primary, secondary, tertiary and quaternary structures).
Protein Functions:
1) protective (interferon is intensively synthesized in the body during a viral infection);
2) structural (collagen is part of tissues, participates in scar formation);
3) motor (myosin is involved in muscle contraction);
4) spare (egg albumins);
5) transport (erythrocyte hemoglobin carries nutrients and metabolic products);
6) receptor (receptor proteins provide recognition by the cell of substances and other cells);
7) regulatory (regulatory proteins determine the activity of genes);
8) hormone proteins are involved in humoral regulation (insulin regulates blood sugar levels);
9) enzyme proteins catalyze all chemical reactions in the body;
10) energy (the breakdown of 1 g of protein releases 17 kJ of energy).
Carbohydrates
These are mono- and polymers, which include carbon, hydrogen and oxygen in a ratio of 1: 2: 1.
Functions of carbohydrates:
1) energy (with the breakdown of 1 g of carbohydrates, 17.6 kJ of energy is released);
2) structural (cellulose, which is part of the cell wall in plants);
3) storage (supply of nutrients in the form of starch in plants and glycogen in animals).
Fats (lipids) can be simple or complex. Simple lipid molecules consist of the trihydric alcohol glycerol and three fatty acid residues. Complex lipids are compounds of simple lipids with proteins and carbohydrates.
Lipid functions:
1) energy (with the breakdown of 1 g of lipids, 38.9 kJ of energy is formed);
2) structural (phospholipids of cell membranes forming a lipid bilayer);
3) storage (supply of nutrients in the subcutaneous tissue and other organs);
4) protective (subcutaneous tissue and a layer of fat around the internal organs protect them from mechanical damage);
5) regulatory (hormones and vitamins containing lipids regulate metabolism);
6) heat-insulating (subcutaneous tissue retains heat). ATP
The ATP (adenosine triphosphoric acid) molecule consists of the nitrogenous base of adenine, the five-carbon sugar of ribose, and three phosphoric acid residues interconnected by a macroergic bond. ATP is produced in mitochondria by phosphorylation. During its hydrolysis, a large amount of energy is released. ATP is the main macroerg of the cell - an energy accumulator in the form of energy of high-energy chemical bonds.
LECTURE № 3. Nucleic acids. Protein biosynthesis
Nucleic acids are phosphorus-containing biopolymers whose monomers are nucleotides. Nucleic acid chains include from several tens to hundreds of millions of nucleotides.
There are 2 types of nucleic acids - deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The nucleotides that make up DNA contain a carbohydrate, deoxy-ribose, while RNA contains ribose.
1. DNA
As a rule, DNA is a helix consisting of two complementary polynucleotide chains twisted to the right. The composition of DNA nucleotides includes: a nitrogenous base, deoxyribose and a phosphoric acid residue. Nitrogenous bases are divided into purine (adenine and guanine) and pyrimidine (thymine and cytosine). Two chains of nucleotides are connected to each other through nitrogenous bases according to the principle of complementarity: two hydrogen bonds occur between adenine and thymine, and three between guanine and cytosine.
DNA functions:
1) ensures the preservation and transmission of genetic information from cell to cell and from organism to organism, which is associated with its ability to replicate;
2) regulation of all processes occurring in the cell, provided by the ability to transcription with subsequent translation.
The process of self-reproduction (auto-reproduction) of DNA is called replication. Replication ensures the copying of genetic information and its transmission from generation to generation, the genetic identity of daughter cells formed as a result of mitosis, and the constancy of the number of chromosomes during mitotic cell division.
Replication occurs during the synthetic period of the interphase of mitosis. The replicase enzyme moves between the two strands of the DNA helix and breaks the hydrogen bonds between the nitrogenous bases. Then, to each of the chains, using the DNA polymerase enzyme, the nucleotides of the daughter chains are completed according to the principle of complementarity. As a result of replication, two identical DNA molecules are formed. The amount of DNA in a cell doubles. This method of DNA duplication is called semi-conservative, since each new DNA molecule contains one "old" and one newly synthesized polynucleotide chain.
