Biology. General biology. Grade 10. Basic level Sivoglazov Vladislav Ivanovich
3. Levels of organization of living matter. Biology methods
Remember!
What levels of organization of living matter do you know?
What scientific research methods do you know?
Levels of organization of living matter. The world of living beings around us is a collection of biological systems of varying degrees of complexity, forming a single hierarchical structure. Moreover, it should be clearly understood that the interconnection of individual biological systems belonging to the same level of organization forms a qualitatively new system. One cell and many cells, one organism and a group of organisms - the difference is not only in quantity. A collection of cells that have a common structure and function is a qualitatively new formation - tissue. A group of organisms is a family, a flock, a population, i.e. a system that has completely different properties than a simple mechanical summation of the properties of several individuals.
In the process of evolution, the organization of living matter gradually became more complex. When a more complex level was formed, the previous level that arose earlier was included in it as a component. That is why level organization and evolution are the hallmarks of living nature. Currently, life as a special form of existence of matter is represented on our planet at several levels of organization (Fig. 4).
Molecular genetic level. No matter how complex the organization of any living system, it is based on the interaction of biological macromolecules: nucleic acids, proteins, carbohydrates, as well as other organic and inorganic substances. From this level, the most important life processes of the body begin: coding and transmission of hereditary information, metabolism, energy conversion.
Cellular level. The cell is the structural and functional unit of all living things. The existence of a cell underlies the reproduction, growth and development of living organisms. There is no life outside the cell, and the existence of viruses only confirms this rule, because they can realize their hereditary information only in the cell.
Rice. 4. Levels of organization of living matter
Tissue level. Tissue is a collection of cells and intercellular substance, united by a common origin, structure and function. In animal organisms, there are four main types of tissue: epithelial, connective, muscle and nervous. Plants are divided into educational, integumentary, conductive, mechanical, basic and excretory (secretory) tissues.
Organ level. An organ is a separate part of the body that has a certain shape, structure, location and performs a specific function. An organ, as a rule, is formed by several tissues, among which one (two) predominates.
Organismal (ontogenetic ) level. An organism is an integral unicellular or multicellular living system capable of independent existence. A multicellular organism is formed, as a rule, by a collection of tissues and organs. The existence of an organism is ensured by maintaining homeostasis (constancy of structure, chemical composition and physiological parameters) in the process of interaction with the environment.
Population-species level. Population is a collection of individuals of the same species living for a long time in a certain territory, within which random crossing occurs to one degree or another and there are no significant internal isolation barriers; it is partially or completely isolated from other populations of the species.
A species is a collection of individuals that are similar in structure, have a common origin, freely interbreed and produce fertile offspring. All individuals of the same species have the same karyotype, similar behavior and occupy a specific area.
At this level, the process of speciation occurs, which occurs under the influence of evolutionary factors.
Biogeocenotic (ecosystem ) level. Biogeocenosis is a historically established collection of organisms of different species that interacts with all factors of their habitat. In biogeocenoses, the circulation of substances and energy takes place.
Biosphere (global ) level. The biosphere is a biological system of the highest rank, covering all life phenomena in the atmosphere, hydrosphere and lithosphere. The biosphere unites all biogeocenoses (ecosystems) into a single complex. All material and energy cycles associated with the life activity of all living organisms living on Earth take place in it.
Thus, life on our planet is represented by self-regulating and self-reproducing systems of various ranks, open to matter, energy and information. The processes of life and development occurring in them ensure the existence and interaction of these systems.
Each level of organization of living matter has its own specific features, therefore, in any biological research, as a rule, a certain level is leading. For example, the mechanisms of cell division are studied at the cellular level, and the main advances in the field of genetic engineering have been achieved at the molecular genetic level. But such a division of problems according to levels of organization is very conditional, because most problems in biology in one way or another concern simultaneously several levels, and sometimes all at once. For example, problems of evolution affect all levels of organization, and genetic engineering methods implemented at the molecular genetic level are aimed at changing the properties of the entire organism.
Methods of knowledge of living nature. By studying systems of varying degrees of complexity, biology uses a variety of methods and techniques. One of the most ancient is observation method, on which it is based descriptive method. Collection of factual material and its description were the main methods of research at the early stage of the development of biology. But even now they have not lost their significance. These methods are widely used by zoologists, botanists, mycologists, ecologists and representatives of many other biological specialties.
In the 18th century became widely used in biology comparative method, which made it possible, in the process of comparing objects, to identify similarities and differences between organisms and their parts. Thanks to this method, the foundations of the taxonomy of plants and animals were laid, and the cell theory was created. The application of this method in anatomy, embryology, and paleontology contributed to the establishment of the evolutionary theory of development in biology.
Historical method allows you to compare existing facts with previously known data, to identify patterns of the appearance and development of organisms, the complexity of their structure and functions.
Of great importance for the development of biology was experimental method, its first use is associated with the name of the Roman physician Galen (2nd century AD). Galen was the first to demonstrate the participation of the nervous system in the organization of behavior and in the functioning of the senses. However, this method began to be widely used only in the 19th century. A classic example of the application of the experimental method is the work of I. M. Sechenov on the physiology of nervous activity and G. Mendel on the study of the inheritance of traits.
Currently, biologists are increasingly using modeling method, which makes it possible to reproduce experimental conditions that are sometimes impossible to recreate in reality. Using computer modeling, for example, it is possible to calculate the consequences of building a dam for a certain ecosystem or to recreate the evolution of a certain type of living organism. By changing the parameters, you can choose the optimal path for the development of agrocenosis or select the safest combination of medications for the treatment of a specific disease.
Any scientific research using different methods consists of several stages. First, as a result of observations, data is collected - data, on the basis of which they put forward hypothesis. In order to evaluate the validity of this hypothesis, a series of experiments is carried out in order to obtain new results. If the hypothesis is confirmed, it may become theory, which includes certain rules And laws.
When solving biological problems, a wide variety of equipment is used: light and electron microscopes, centrifuges, chemical analyzers, thermostats, computers and many other modern devices and tools.
A real revolution in biological research was made by the advent of the electron microscope, in which a beam of electrons is used instead of a light beam. The resolution of such a microscope is 100 times higher than that of a light microscope.
One type of electron microscope is a scanning one. In it, the electron beam does not pass through the sample, but is reflected from it and converted into an image on a television screen. This allows you to obtain a three-dimensional image of the object under study.
Review questions and assignments
1. Why do you think it is necessary to distinguish different levels of organization of living matter?
2. List and characterize the levels of organization of living matter.
3. Name the biological macromolecules that make up living systems.
4. How do the properties of living things manifest themselves at different levels of organization?
5. What methods of studying living matter do you know?
6. Can a multicellular organism not have tissues and organs? If you think it can, give examples of such organisms.
Rice. 5. Amoeba under a microscope
Think! Do it!
1. Highlight the main features of the concept “biological system”.
2. Do you agree that the descriptive period in biology continues into the 21st century? Justify your answer.
3. Look at Fig. 5. Determine which image was obtained using light microscopy, which was obtained using electron microscopy, and which was the result of using a scanning microscope. Explain your choice.
4. From previous courses in biology, physics, chemistry or other subjects, remember some theory (law or rule) that you know well. Try to describe the main stages of its (his) formation.
5. Using additional literature and Internet resources, prepare a presentation or a colorful stand on the topic “Modern scientific equipment and its role in solving biological problems.” What equipment have you already become acquainted with while studying the course “Man and His Health”? For what purposes is it used? Can medical equipment be considered biological? Explain your point of view.
Work with computer
Refer to the electronic application. Study the material and complete the assignments.
Repeat and remember!
Plants
The appearance of plant tissues and organs. The appearance of tissues and organs in the evolution of plants was associated with access to land. Algae do not have organs or specialized tissues, since all their cells are in the same conditions (temperature, light, mineral nutrition, gas exchange). Each algae cell usually contains chloroplasts and is capable of photosynthesis.
However, having reached land, the ancestors of modern higher plants found themselves in completely different conditions: plants had to obtain oxygen necessary for respiration and carbon dioxide used for photosynthesis from the air, and water from the soil. The new habitat was not homogeneous. Problems arose that had to be solved: protection from drying out, absorption of water from the soil, creation of mechanical support, preservation of spores. The existence of plants on the border of two environments - soil and air - led to the emergence of polarity: the lower part of the plant, plunging into the soil, absorbed water with minerals dissolved in it, the upper part, remaining on the surface, actively photosynthesized and provided the entire plant with organic substances. This is how the two main vegetative organs of modern higher plants appeared - the root and the shoot.
This division of the plant body into separate organs, the complication of their structure and functions, occurred gradually in the process of the long evolution of the plant world and was accompanied by a complication of tissue organization.
The first to appear was the covering tissue, which protected the plant from drying out and damage. The underground and above-ground parts of the plant should have been able to exchange various substances. Water with mineral salts dissolved in it rose up from the soil, and organic matter moved down to the underground parts of the plant that were not capable of photosynthesis. This required the development of conducting tissues - xylem and phloem. In the air, it was necessary to resist the forces of gravity and withstand gusts of wind - this required the development of mechanical tissue.
In higher plants, vegetative and generative (reproductive) organs are distinguished. The vegetative organs of higher plants are the root and shoot, consisting of stem, leaves and buds. Vegetative organs provide photosynthesis and respiration, growth and development, absorption and transport of water and mineral salts dissolved in it in the plant body, transport of organic substances, and also participate in vegetative propagation.
Generative organs are sporangia, spore-bearing spikelets, cones and flowers that form fruits and seeds. They appear at certain periods of life and perform functions related to plant reproduction.
Human
Methods for studying man. One of the first anatomical methods, starting from the Renaissance, was the method autopsy(autopsy of corpses). However, currently there are many methods that allow one to study an organism in vivo: fluoroscopy, ultrasound, magnetic resonance imaging and many others.
The basis of all physiological methods is observations And experiments. Modern physiologists successfully use a variety of instrumental methods. Electrocardiogram hearts, electroencephalogram brain, thermography(obtaining thermal photographs), radiography(introduction of radio tags into the body), various endoscopy(examinations of internal organs using special devices - endoscopes) help specialists not only study the functioning of the body, but also identify diseases and disorders in the functioning of organs in the early stages. Blood pressure, blood and urine tests can tell a lot about a person’s health.
The main methods of psychology are observations, questionnaires, experiment.
Hygiene, along with the methods used in other sciences, has its own specific research methods: epidemiological, sanitary survey, sanitary examination, health education and some others.
Your future profession
1. Assess the role of science in the life of each person and society as a whole. Write an essay on this topic. Discuss as a class whether there are currently professional activities that are not affected by scientific developments.
2. Assess the importance of information in modern society. What is the role of information in successful professional growth? Explain the meaning of the statement of British Prime Minister Winston Churchill (1874–1965) “He who owns the information owns the world.”
3. Try to simulate situations in which you might benefit from the knowledge you gained from studying this chapter.
4. Specialty is a complex of knowledge, skills and abilities acquired through special training and work experience, necessary for a certain type of activity within a particular profession. Profession is a socially significant occupation of a person, the type of his activity. Determine which of the list below belongs to the specialty and which to the profession: biology, environmental engineer, biotechnologist, ecology, genetic engineer, molecular biologist. Give reasons for your choice.
5. What specialty do you plan to acquire during your further studies? Have you already decided on your choice of profession?
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LEVELS OF LIFE ORGANIZATION
Living nature is an integral, but heterogeneous system, which is characterized by hierarchical organization. Under system, in science they understand unity, or integrity, made up of many elements that are in regular relationships and connections with each other. The main biological categories, such as genome (genotype), cell, organism, population, biogeocenosis, biosphere, are systems. Hierarchical is a system in which the parts, or elements, are arranged in order from lowest to highest. Thus, in living nature, the biosphere is composed of biogeocenoses, represented by populations of organisms of different species, and the bodies of organisms have a cellular structure.
The hierarchical principle of organization allows us to distinguish individual levels, which is convenient from the point of view of studying life as a complex natural phenomenon.
In biomedical science they widely use level classification in accordance with the most important parts, structures and components of the body, which are direct objects of study for researchers of various specialties. Such objects can be the organism as such, organs, tissues, cells, intracellular structures, molecules. The identification of levels of the classification under consideration is in good agreement with the resolution of the methods used by biologists and doctors: studying an object with the naked eye, using a magnifying glass, a light-optical microscope, an electron microscope, and modern physical and chemical methods. The connection between these levels and the typical sizes of the biological objects being studied is obvious (Table 1.1).
Table 1.1. Level of organization (study) distinguished in a multicellular organism (according to E. Ds. Roberts et al., 1967, as amended)
The interpenetration of ideas and methods of various fields of natural science (physics, chemistry, biology), the emergence of sciences at the intersection of these fields (biophysics, biochemistry, molecular biology) led to the expansion of the classification, up to the separation of the molecular and electron-atomic levels. Biomedical research conducted at these levels is already providing practical access to healthcare. Thus, devices based on the phenomena of electron paramagnetic and nuclear magnetic resonance are successfully used to diagnose diseases and conditions of the body.
The ability to study fundamental biological processes occurring in the body at the cellular, subcellular and even molecular levels is an outstanding, but not the only distinguishing feature of modern biology. She is characterized by a deep interest in the processes in communities of organisms that determine the planetary role of life.
Thus, the classification was replenished with supraorganism levels, such as species, biogeocenotic, and biosphere.
The classification discussed above is followed by the majority of specific biomedical and anthropobiological sciences. This is not surprising, since it reflects the levels of organization of living nature through historically established levels of its study. The goal of a medical school biology course is to teach the most complete description of the biological “heritage” of people. To solve this problem, it is advisable to use a classification that most closely reflects exactly levels of life organization.
In this classification, molecular genetic, cellular, organismal, or ontogenetic, population-species, and biogeocenotic levels are distinguished. The peculiarity of this classification is that the individual levels of the hierarchical system of life are defined in it on a general basis of allocation for each level elementary unit And elementary phenomenon. An elementary unit is a structure or object, the regular changes of which, designated as an elementary phenomenon, constitute a contribution specific to the corresponding level to the process of preservation and development of life. The correspondence of the identified levels to the key moments of the evolutionary process, outside of which not a single living creature stands, makes them universal, extending to the entire area of life, including humans.
Elementary unit on molecular genetic level serves as a gene - a fragment of a nucleic acid molecule in which a certain amount of biological (genetic) information is recorded in a qualitative and quantitative sense. The elementary phenomenon lies primarily in the process convariant reduplication, or self-reproduction, with the possibility of some changes in the content of information encoded in the gene. By reduplicating DNA, the biological information contained in genes is copied, which ensures continuity and preservation (conservatism) of the properties of organisms over a number of generations. Reduplication is thus the basis of heredity.
Due to the limited stability of molecules or errors in DNA synthesis (from time to time, but inevitably), disturbances occur that change the information of genes. In subsequent DNA reduplication, these changes are reproduced in copy molecules and are inherited by organisms of the daughter generation. These changes arise and are replicated naturally, which makes DNA reduplication convariant, i.e. sometimes occurring with some changes. These changes in genetics are called genetic(or true) mutations. Reduplication convariance thus serves as the basis for mutational variability.
Biological information contained in DNA molecules is not directly involved in life processes. It transforms into its active form by being transferred into protein molecules. The noted transfer is carried out thanks to the mechanism matrix synthesis, in which the original DNA serves, as in the case of reduplication, as a matrix (form), but for the formation not of a daughter DNA molecule, but of messenger RNA, which controls the biosynthesis of proteins. The above gives grounds to classify the matrix synthesis of information macromolecules as an elementary phenomenon at the molecular genetic level of life organization.
The embodiment of biological information into specific life processes requires special structures, energy and a variety of chemicals (substrates). The conditions described above in living nature are provided by the cell, which serves as an elementary structure cellular level. An elementary phenomenon is presented reactions of cellular metabolism, forming the basis of flows of energy, substances and information. Thanks to the activity of the cell, substances coming from outside are converted into substrates and energy, which are used (in accordance with the available genetic information) in the process of biosynthesis of proteins and other compounds necessary for the body. Thus, at the cellular level, the mechanisms of transmission of biological information and the transformation of substances and energy are coupled. An elementary phenomenon at this level serves as the energetic and material basis of life at all other levels of its organization.
Elementary unit body/that level is individual in its development from the moment of origin to the cessation of existence as a living system, which allows us to also call this level ontogenetic. Regular changes in the body in individual development constitute an elementary phenomenon at this level. These changes ensure the growth of the organism, the differentiation of its parts and at the same time the integration of development into a single whole, the specialization of cells, organs and tissues. During ontogenesis, under certain environmental conditions, the embodiment of hereditary information into biological structures and processes occurs, and the phenotype of organisms of a given species is formed on the basis of the genotype.
Elementary unit population-species level serves population - a collection of individuals of the same species. The unification of individuals into a population occurs due to community gene pool, used in the process of sexual reproduction to create genotypes of individuals of the next generation. The population, due to the possibility of interpopulation crossings, is open genetic system. The effect on the gene pool of a population of elementary evolutionary factors, such as the mutation process, fluctuations in the number of individuals, natural selection, leads to evolutionarily significant changes in the gene pool, which represent elementary phenomena at a given level.
Organisms of one species inhabit an area with known abiotic indicators (climate, soil chemistry, hydrological conditions) and interact with organisms of other species. In the process of joint historical development in a certain territory of organisms of different systematic groups, dynamic, time-stable communities are formed - biogeocenoses, which serve as the elementary unit biogeocenotic(ecosystem) level. The elementary phenomenon at the level under consideration is represented by energy flows and cycles of substances. The leading role in these cycles and flows belongs to living organisms. Biogeocenosis is a materially and energetically open system. Biogeocenoses, differing in species composition and characteristics of their abiotic part, are united on the planet into a single complex - the area of distribution of life, or biosphere.
The above levels reflect the most important biological phenomena, without which evolution and, consequently, the very existence of life are impossible. Although the elementary units and phenomena at the identified levels are different, they are all closely interconnected, solving their specific task within the framework of a single evolutionary process. The elementary foundations of this process in the form of the phenomena of heredity and true mutational variability are associated with convariant reduplication at the molecular genetic level. The special role of the cellular level is to provide energetic, material and informational support for what is happening at all other levels. At the ontogenetic level, biological information contained in genes is transformed into a complex of characteristics and properties of the organism. The phenotype thus arising becomes available to the action of natural selection. At the population-species level, the evolutionary value of changes related to the molecular genetic, cellular and ontogenetic levels is determined. The specific role of the biogeocenotic level is the formation of communities of organisms of different species adapted to living together in a certain habitat. An important distinguishing feature of such communities is their stability over time.
The levels considered reflect the general structure of the evolutionary process, the natural result of which is man. Therefore, the elementary structures and phenomena typical of these levels also apply to people, although with some peculiarities due to their social essence.
Molecular genetic. The elementary unit of organization is the gene. An elementary phenomenon is DNA reduplication, the transfer of genetic information to a daughter cell. The molecular level of organization of life is the subject of study of molecular biology. She studies the structure of proteins, their functions (including as enzymes), the role of nucleic acids in the storage, replication and implementation of genetic information, i.e. processes of synthesis of DNA, RNA, proteins.
Cellular level. This level of organization of living things is represented by cells - independent organisms (bacteria, protozoa, etc.), as well as cells of multicellular organisms. The most important specific feature of the cellular level is that from this level life begins, since matrix synthesis occurring at the molecular level occurs in cells. Being capable of life, growth and reproduction, cells are the main form of organization of living matter, its elementary units from which all living beings are built. A characteristic feature of the cellular level is cell specialization. At the cellular level, there is a differentiation and ordering of life processes in space and time.
Tissue level. Tissue is a collection of cells that have a common origin, similar structure and perform the same functions. In mammals, for example, there are four main types of tissue: epithelial, connective, muscle and nervous.
Organismal (ontogenetic) level. At the organismal level, they study the individual and its structural features as a whole, physiological processes, including differentiation, mechanisms of adaptation and behavior. The elementary indivisible unit of life organization at this level is the individual. Life is always represented in the form of discrete individuals. These can be single-celled individuals, or multicellular, consisting of millions and billions of cells.
Population-species level. The basic elementary structural unit at this level is the population. Population- a local, geographically separated to one degree or another from others group of individuals of the same species, freely interbreeding with each other and having a common genetic fund. The elementary phenomenon of the population-species level is a change in the genotypic composition of the population, and the elementary material is mutation. At the population-species level, factors influencing the size of populations, problems of conservation of endangered species, and the dynamics of the genetic composition of populations are studied.
Biocenotic level. Populations of different species always form complex communities in the Earth's biosphere. Such communities in specific areas of the biosphere are called biocenoses. Biocenosis– a complex consisting of a plant community (phytocenosis), the animal world inhabiting it (zoocenosis), microorganisms and the corresponding area of the earth’s surface. All components of the biocenosis are interconnected by the cycle of substances. Biocenosis is a product of the joint historical development of species that differ in systematic position.
1. Levels of life organization
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 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 organic compounds from inorganic substances 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 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 forms of 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 and protein molecules. 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 characteristics 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 shifts in metabolism, electrical potential on cell membranes, physicochemical parameters in the cytoplasm of cells, in motor reactions, and highly organized animals are characterized by changes in their behavior.
4. The 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.
There are 8 of them in total. What underlies the division of living nature into levels? The fact is that at each level there are certain properties. Each next level necessarily contains the previous one or all previous ones. Let's look at each level in detail:
1. Molecular level of organization of living nature
· Organic and inorganic substances,
processes of synthesis and breakdown of these substances,
release and absorption of energy
These are all chemical processes that occur inside any living system. This level cannot be called “live” 100%. It is rather a “chemical level” - therefore it is the very first, the lowest of all. But it was precisely this level that formed the basis for the division of Living Nature into kingdoms - according to the reserve nutrient: in plants - carbohydrates, in fungi - chitin, in animals - protein.
· Biochemistry
· Molecular biology
· Molecular genetics
2. Cellular level of organization of living nature
Includes molecular level of organization. At this level, “the smallest indivisible biological system—the cell”—already appears. Your metabolism and energy. The internal organization of a cell is its organelles. Life processes - origin, growth, self-reproduction (division)
Sciences that study the cellular level of organization:
Cytology
· (Genetics)
· (Embryology)
The sciences that study this level are indicated in brackets, but this is not the main object of study.
3. Tissue level of organization
Includes molecular and cellular levels. This level can be called “multicellular” - after all, tissue is a collection of cells with a similar structure and performing the same functions.
The science that studies the tissue level of organization - histology.
4. Organ level of life organization
In unicellular organisms these are organelles - each has its own structure and functions
In multicellular organisms, these are organs that are united into systems and clearly interact with each other.
These two levels - tissue and organ - are studied by science:
Botany - plants,
Zoology - animals,
Anatomy - human
· Physiology
· (medicine)
5. Organismal level
Includes molecular, cellular, tissue and organ levels.
At this level, living nature is already divided into kingdoms - plants, fungi and animals.
Properties of this level:
· Metabolism (and at the cellular level too - you see, each level contains the previous one!)
· Structure of the body
· Nutrition
Homeostasis - constancy of the internal environment
· Reproduction
Interaction between organisms
· Interaction with the environment
Anatomy
· Genetics
· Morphology
· Physiology
6. Population-species level of life organization
Includes molecular, cellular, tissue, organ and organism levels.
If several organisms are morphologically similar (in other words, they have the same structure) and have the same genotype, then they form one species or population.
Main processes at this level:
Interaction of organisms with each other (either competition or reproduction)
microevolution (changes in the body under the influence of external conditions)
Sciences studying this level:
· Genetics
· Evolution
Ecology
7. Biogeocenotic level of life organization (from the word biogeocenosis)
At this level, almost everything is already taken into account:
Interaction of organisms with each other - food chains and networks
Interaction of organisms with each other - competition and reproduction
The influence of the environment on organisms and, accordingly, the influence of organisms on their habitat
The science that studies this level is Ecology.
8. Biosphere level of organization of living nature (the last level is the highest!)
It includes:
· Interaction of living and nonliving components of nature
· Biogeocenoses
· Human influence - “anthropogenic factors”
· Cycle of substances in nature
And studies all this - Ecology!
The scientific world started talking about the cell almost immediately after the invention of the microscope.
By the way, there are now quite a few types of microscopes:
Optical microscope - maximum magnification - ~2000 times (you can see some microorganisms, cells (plant and animal), crystals, etc.
Electron microscope - magnifies up to 106 times. You can already study particles of both cells and molecules - this is already the level of microstructures
The first scientist who was able to see cells (through a microscope, of course) was Robert Hooke(1665) - he studied the cellular structure mainly of plants.
But for the first time I started talking about single-celled organisms - bacteria, ciliates A. Van Leeuwenhoek(1674 g)
La Marque(1809) already began to talk about the cell theory
Well, already in the middle of the 19th century, M. Schleiden and T. Schwann formulated the cell theory, which is now generally accepted throughout the world.
All organisms are cellular except viruses
Cell- an elementary unit of structure and vital activity of all organisms, having its own metabolism, capable of independent existence, self-reproduction and development. All living organisms either, like multicellular animals, plants and fungi, consist of many cells, or, like many protozoa and bacteria, are single-celled organisms. The branch of biology that studies the structure and functioning of cells is called cytology. Recently, it has also become common to talk about cell biology, or cell biology.
Cell is a mini-organism. She has her own “organs” - organoids. The main organelle of the cell is the nucleus. On this basis, all living organisms are divided into EUKARYOTIC (“karyo” - nucleus) - containing a nucleus and PROKARYOTIC (“pro” - do) - prenuclear (without a nucleus)
Provisions of the Schleiden-Schwann cell theory
1. All animals and plants are made up of cells.
2. Plants and animals grow and develop through the emergence of new cells.
3. A cell is the smallest unit of living things, and a whole organism is a collection of cells.
Basic provisions of modern cell theory
· A cell is a unit of structure, vital activity, growth and development of living organisms; there is no life outside the cell.
· A cell is a single system consisting of many elements naturally interconnected with each other, representing a certain integral formation.
· The nucleus is the main component of the cell (eukaryotes).
· New cells are formed only as a result of the division of original cells.
· Cells of multicellular organisms form tissues, tissues form organs. The life of an organism as a whole is determined by the interaction of its constituent cells.
The main organoids of a cell are those components that are inherent in all cells of living organisms - the “general composition”:
· nucleus: nucleolus; nuclear envelope;
· plasma membrane;
· endoplasmic reticulum;
· centriole;
· Golgi complex;
· lysosome;
· vacuole;
· mitochondrion.
Nucleic acids found in the cells of absolutely any organism. Even viruses.
"Nucleo" - "nucleus" - are mainly found in the nucleus of cells, but are also found in the cytoplasm and other organelles. There are two types of nucleic acids: DNA and RNA
DNA - deoxyribonucleic acid
RNA - ribonucleic acid
These molecules are polymers; the monomers are nucleotides - compounds containing nitrogenous bases.
DNA nucleotides: A - adenine, T - thymine, C - cytosine, G - guanine
RNA nucleotides: A - adenine, U - uracil, C - cytosine, G - guanine
As you can see, there is no thymine in RNA, it is replaced by uracil - U
In addition to them, nucleotides include:
carbohydrates: deoxyribose - in DNA, ribose - in RNA. Phosphate and sugar - are part of both molecules
This is the primary structure of molecules
Secondary structure is the very shape of molecules. DNA is a double helix, RNA is a “single” long molecule.
Basic functions of nucleic acids
The genetic code is the sequence of nucleotides in a DNA molecule. This is the basis of any organism; in fact, it is information about the organism itself (like any person’s full name, which identifies a person - this is a sequence of letters, or a sequence of numbers - a passport series).
So, basic functions of nucleic acids- in the storage, implementation and transmission of hereditary information “recorded” in molecules in the form of a sequence of certain nucleotides.
Cell division is part of the life process of absolutely any living organism. All new cells are formed from old (mother) cells. This is one of the main provisions of cell theory. But there are several types of division that directly depend on the nature of these cells.
Prokaryotic cell division
How does a prokaryotic cell differ from a eukaryotic cell? The most important difference is the absence of a core (which is actually why they are called that). The absence of a nucleus means that the DNA simply resides in the cytoplasm.
The process looks like this:
DNA replication (duplication) ---> cell lengthens ---> transverse septum is formed ---> cells separate and move apart
Eukaryotic cell division
The life of any cell consists of 3 stages: growth, preparation for division and, in fact, division.
How do you prepare for division?
First, protein is synthesized
· secondly, all the important components of the cell are doubled so that each new cell has the entire set of organelles necessary for life.
· Thirdly, the DNA molecule doubles and each chromosome synthesizes a copy of itself. Double chromosome = 2 chromatids (each with a DNA molecule).
This period of preparation for delusion is called INTERPHASE.