There are such levels of organization of living matter - levels of biological organization: molecular, cellular, tissue, organ, organism, population-species and ecosystem.
Molecular level of organization- this is the level of functioning of biological macromolecules - biopolymers: nucleic acids, proteins, polysaccharides, lipids, steroids. From this level, the most important life processes begin: metabolism, energy conversion, transfer hereditary information. This level is studied: biochemistry, molecular genetics, molecular biology, genetics, biophysics.
Cellular level- this is the level of cells (cells of bacteria, cyanobacteria, unicellular animals and algae, unicellular fungi, cells of multicellular organisms). A cell is a structural unit of the living, a functional unit, a unit of development. This level is studied by cytology, cytochemistry, cytogenetics, microbiology.
Tissue level of organization- This is the level at which the structure and functioning of tissues is studied. This level is studied by histology and histochemistry.
Organ level of organization- This is the level of organs of multicellular organisms. Anatomy, physiology, embryology study this level.
Organismal level of organization- this is the level of unicellular, colonial and multicellular organisms. The specificity of the organismic level is that at this level the decoding and implementation of genetic information takes place, the formation of features inherent in individuals of a given species. This level is studied by morphology (anatomy and embryology), physiology, genetics, paleontology.
Population-species level is the level of populations of individuals - populations and species. This level is studied by systematics, taxonomy, ecology, biogeography, population genetics. At this level, genetic and ecological features of populations, elementary evolutionary factors and their impact on the gene pool (microevolution), the problem of species conservation.
Ecosystem level of organization- this is the level of microecosystems, mesoecosystems, macroecosystems. At this level, types of nutrition are studied, types of relationships between organisms and populations in an ecosystem, population size, population dynamics, population density, ecosystem productivity, successions. This level studies ecology.
Allocate also biospheric level of organization living matter. The biosphere is a giant ecosystem that occupies part of the geographic envelope of the Earth. This is a mega ecosystem. The biosphere is cycling and chemical elements, as well as the conversion of solar energy.
2. Fundamental properties of living matter
Metabolism (metabolism)
Metabolism (metabolism) is a set of chemical transformations occurring in living systems that ensure their vital activity, growth, reproduction, development, self-preservation, constant contact with the environment, the ability to adapt to it and its changes. In the process of metabolism, splitting and synthesis of molecules that make up cells occur; formation, destruction and renewal of cellular structures and intercellular substance. Metabolism is based on interrelated processes of assimilation (anabolism) and dissimilation (catabolism). Assimilation - the processes of synthesis of complex molecules from simple ones with the expenditure of energy stored during dissimilation (as well as the accumulation of energy during the deposition of synthesized substances in the reserve). Dissimilation - the processes of splitting (anaerobic or aerobic) of complex organic compounds, going with the release of energy necessary for the implementation of the vital activity of the organism. Unlike bodies of inanimate nature, exchange with the environment for living organisms is a condition for their existence. In this case, self-renewal occurs. Metabolic processes occurring inside the body are combined into metabolic cascades and cycles by chemical reactions, which are strictly ordered in time and space. The coordinated flow of a large number of reactions in a small volume is achieved by the ordered distribution of individual metabolic links in the cell (the principle of compartmentalization). Metabolic processes are regulated with the help of biocatalysts - special proteins-enzymes. Each enzyme has substrate specificity to catalyze the conversion of only one substrate. This specificity is based on a peculiar "recognition" of the substrate by the enzyme. Enzymatic catalysis differs from non-biological in its extremely high efficiency, as a result of which the rate of the corresponding reaction increases by 1010 - 1013 times. Each enzyme molecule is capable of performing from several thousand to several million operations per minute without being destroyed in the process of participating in reactions. Another characteristic difference between enzymes and non-biological catalysts is that enzymes are able to accelerate reactions under normal conditions (atmospheric pressure, body temperature, etc.). All living organisms can be divided into two groups - autotrophs and heterotrophs, differing in sources of energy and necessary substances for their life. Autotrophs - organisms that synthesize organic compounds from inorganic substances using the energy of sunlight (photosynthetics - green plants, algae, some bacteria) or the energy obtained from the oxidation of an inorganic substrate (chemosynthetics - sulfur, iron bacteria and some others), Autotrophic organisms are able to synthesize all components of the cell. The role of photosynthetic autotrophs in nature is decisive - being the primary producer of organic matter in the biosphere, they ensure the existence of all other organisms and the course of biogeochemical cycles in the circulation of substances on Earth. Heterotrophs (all animals, fungi, most bacteria, some chlorophyll-free plants) are organisms that need ready-made organic substances for their existence, which, acting as food, serve as both a source of energy and a necessary "building material". A characteristic feature of heterotrophs is the presence of amphibolism in them, i.e. the process of formation of small organic molecules (monomers) formed during the digestion of food (the process of degradation of complex substrates). Such molecules - monomers are used to assemble their own complex organic compounds.
Self-reproduction (reproduction)
The ability to reproduce (reproduce their own kind, self-reproduction) refers to one of the fundamental properties of living organisms. Reproduction is necessary in order to ensure the continuity of the existence of species, because. the lifespan of an individual organism is limited. Reproduction more than compensates for the losses caused by the natural extinction of individuals, and thus maintains the preservation of the species in a number of generations of individuals. In the process of evolution of living organisms, the evolution of methods of reproduction took place. Therefore, the current numerous and diverse different types living organisms we find different forms breeding. Many types of organisms combine several methods of reproduction. It is necessary to distinguish two fundamentally different types of reproduction of organisms - asexual (primary and more ancient type of reproduction) and sexual. In the process of asexual reproduction, a new individual is formed from one or a group of cells (in multicellular) of the mother organism. In all forms of asexual reproduction, the offspring have a genotype (set of genes) identical to the maternal one. Consequently, all the offspring of one maternal organism turns out to be genetically homogeneous and the daughter individuals have the same set of traits. During sexual reproduction, a new individual develops from a zygote formed by the fusion of two specialized germ cells (fertilization process) produced by two parental organisms. The nucleus in the zygote contains a hybrid set of chromosomes, which is formed as a result of the union of sets of chromosomes of fused gamete nuclei. In the nucleus of the zygote, thus, a new combination of hereditary inclinations (genes) is created, brought in equally by both parents. And the daughter organism developing from the zygote will have a new combination of features. In other words, during sexual reproduction, the implementation of a combinative form of hereditary variability of organisms occurs, which ensures the adaptation of species to changing environmental conditions and is an essential factor in evolution. This is a significant advantage of sexual reproduction over asexual reproduction. The ability of living organisms to self-reproduce is based on the unique property of nucleic acids to reproduce and the phenomenon of matrix synthesis, which underlies the formation of nucleic acid molecules and proteins. Self-reproduction at the molecular level determines both the implementation of metabolism in cells and the self-reproduction of the cells themselves. Cell division (self-reproduction of cells) underlies the individual development of multicellular organisms and the reproduction of all organisms. The reproduction of organisms ensures the self-reproduction of all species inhabiting the Earth, which in turn determines the existence of biogeocenoses and the biosphere.
Heredity and variability
Heredity provides material continuity (the flow of genetic information) between generations of organisms. It is closely related to reproduction at the molecular, subcellular and cellular levels. Genetic information that determines the diversity of hereditary traits is encrypted in the molecular structure of DNA (for some viruses, in RNA). The genes encode information about the structure of synthesized proteins, enzymatic and structural. The genetic code is a system of "recording" information about the sequence of amino acids in synthesized proteins using the sequence of nucleotides in the DNA molecule. The totality of all the genes of an organism is called the genotype, and the totality of traits is called the phenotype. The phenotype depends on both the genotype and the factors of the internal and external environment that affect the activity of genes and determine regular processes. The storage and transmission of hereditary information is carried out in all organisms with the help of nucleic acids, the genetic code is the same for all living beings on Earth, i.e. it is universal. Due to heredity, traits are transmitted from generation to generation that ensure the adaptability of organisms to their environment. If during the reproduction of organisms only the continuity of existing signs and properties was manifested, then against the background of changing environmental conditions, the existence of organisms would be impossible, since a necessary condition for the life of organisms is their adaptability to environmental conditions. There is variability in the diversity of organisms belonging to the same species. Variability can be realized in individual organisms in the course of their individual development or within a group of organisms in a series of generations during reproduction. There are two main forms of variability, differing in the mechanisms of occurrence, the nature of the change in characteristics and, finally, their significance for the existence of living organisms - genotypic (hereditary) and modification (non-hereditary). Genotypic variability is associated with a change in the genotype and leads to a change in the phenotype. The basis of genotypic variability may be mutations (mutational variability) or new combinations of genes that arise in the process of fertilization during sexual reproduction. In the mutational form, changes are associated primarily with errors in the replication of nucleic acids. Thus, the emergence of new genes that carry new genetic information; new signs appear. And if the newly emerging signs are useful to the organism in specific conditions, then they are "caught up" and "fixed" by natural selection. Thus, the adaptability of organisms to environmental conditions, the diversity of organisms are based on hereditary (genotypic) variability, and the prerequisites for positive evolution are created. With non-hereditary (modification) variability, changes in the phenotype occur under the influence of environmental factors and are not associated with a change in the genotype. Modifications (changes in traits with modification variability) occur within the normal range of the reaction, which is under the control of the genotype. Modifications are not passed on to future generations. The value of modification variability lies in the fact that it ensures the adaptability of the organism to environmental factors during its life.
Individual development of organisms
All living organisms are characterized by the process of individual development - ontogenesis. Traditionally, ontogenesis is understood as the process of individual development of a multicellular organism (formed as a result of sexual reproduction) from the moment of formation of a zygote to the natural death of an individual. Due to the division of the zygote and subsequent generations of cells, a multicellular organism is formed, consisting of a huge number of different types of cells, various tissues and organs. The development of an organism is based on the "genetic program" (embodied in the genes of the chromosomes of the zygote) and is carried out in specific environmental conditions that significantly affect the process of implementing genetic information during the individual existence of an individual. In the early stages of individual development, intensive growth occurs (increase in mass and size), due to the reproduction of molecules, cells and other structures, and differentiation, i.e. appearance of differences in structure and complication of functions. At all stages of ontogenesis, various environmental factors (temperature, gravity, pressure, food composition in terms of the content of chemical elements and vitamins, various physical and chemical agents) have a significant regulatory influence on the development of the organism. The study of the role of these factors in the process of individual development of animals and humans is of great practical importance, which increases with the intensification of anthropogenic impact on nature. In various fields of biology, medicine, veterinary medicine and other sciences, research is being widely carried out to study the processes of normal and pathological development of organisms, to elucidate the patterns of ontogenesis.
Irritability
An integral property of organisms and all living systems is irritability - the ability to perceive external or internal stimuli (impact) and 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. Central dogma of molecular biology- a rule generalizing the implementation of genetic information observed in nature: information is transmitted from nucleic acids to squirrel but not in the opposite direction. The rule was formulated Francis Crick in 1958 year and brought into line with the data accumulated by that time in 1970 year. Transfer of genetic information from DNA to RNA and from RNA to squirrel is universal for all cellular organisms without exception; it underlies the biosynthesis of macromolecules. Genome replication corresponds to the DNA → DNA informational transition. In nature, there are also transitions RNA → RNA and RNA → DNA (for example, in some viruses), as well as a change conformations proteins transferred from molecule to molecule.
Universal ways of transferring biological information
In living organisms, there are three types of heterogeneous, that is, consisting of different polymer monomers - DNA, RNA and protein. The transfer of information between them can be carried out in 3 x 3 = 9 ways. The central dogma divides these 9 types of information transfer into three groups:
General - found in most living organisms;
Special - occurring as an exception, in viruses and at mobile elements of the genome or under biological conditions experiment;
Unknown - not found.
DNA replication (DNA → DNA)
DNA is the main way information is transmitted between generations of living organisms, so the exact duplication (replication) of DNA is very important. Replication is carried out by a complex of proteins that unwind chromatin, then a double helix. After that, DNA polymerase and its associated proteins build an identical copy on each of the two strands.
Transcription (DNA → RNA)
Transcription is a biological process, as a result of which the information contained in a DNA segment is copied onto a synthesized molecule. messenger RNA. Transcription is carried out transcription factors and RNA polymerase. AT eukaryotic cell the primary transcript (pre-mRNA) is often edited. This process is called splicing.
Translation (RNA → protein)
Mature mRNA is read ribosomes during the translation process. AT prokaryotic In cells, the process of transcription and translation is not spatially separated, and these processes are conjugated. AT eukaryotic transcription site in cells cell nucleus separated from the broadcast site ( cytoplasm) nuclear membrane, so mRNA transported from the nucleus into the cytoplasm. mRNA is read by the ribosome in the form of three nucleotide"words". complexes initiation factors and elongation factors deliver aminoacylated transfer RNAs to the mRNA-ribosome complex.
5. reverse transcription is the process of forming a double-stranded DNA on a single-stranded matrix RNA. This process is called reverse transcription, since the transfer of genetic information in this case occurs in the “reverse” direction relative to transcription.
The idea of reverse transcription was initially very unpopular, as it contradicted central dogma of molecular biology, which suggested that DNA transcribed to RNA and beyond broadcast into proteins. Found in retroviruses, for example, HIV and in case retrotransposons.
transduction(from lat. transductio- movement) - transfer process bacterial DNA from one cell to another bacteriophage. General transduction is used in bacterial genetics to genome mapping and design strains. Both temperate and virulent phages are capable of transduction, the latter, however, destroy the bacterial population, so transduction with their help does not have of great importance either in nature or in research.
A vector DNA molecule is a DNA molecule that acts as a carrier. The carrier molecule must have a number of features:
Ability to autonomously replicate in a host cell (usually bacterial or yeast)
The presence of a selectable marker
Availability of convenient restriction sites
The most common vectors are bacterial plasmids.
Levels of organization of wildlife
Allocate 8 levels.
Each level of organization is characterized by a specific structure (chemical, cellular or organismal) and the corresponding properties.
Each next level necessarily contains all the previous ones.
Let's take a look at each level in detail.
8 levels of wildlife organization
1. Molecular level of organization of living nature
- : organic and inorganic substances,
- (metabolism): processes of dissimilation and assimilation,
- absorption and release of energy.
The molecular level affects all biochemical processes that occur inside any living organism - from unicellular to multicellular.
This level difficult to call "alive". It is rather a "biochemical" level - therefore it is the basis for all other levels of organization of living nature.
Therefore, it was he who formed the basis of the classification to the kingdoms which nutrient is the main one in the body: in animals -, in fungi - chitin, in plants it is -.
Sciences that study living organisms at this level:
2. Cellular level of wildlife organization
Includes previous - molecular level of organization.
At this level, the term "" already appears as "the smallest indivisible biological system"
- The metabolism and energy of a given cell (different depending on which kingdom the organism belongs to);
- Organoids of the cell;
- Life cycles - origin, growth and development and cell division
Sciences studying cellular level of organization:
Genetics and embryology study this level, but this is not the main object of study.
3. Tissue level of organization:
Includes 2 previous levels - molecular and cellular.
This level can be called multicellular"- because the fabric is collection of cells with a similar structure and performing the same functions.
Science - Histology
4. Organ(stress on the first syllable) level of organization of life
- In unicellular organs, these are organelles - there are common organelles - characteristic of all or prokaryotic cells, there are different ones.
- Cells in multicellular organisms general structure and functions are combined into tissues, and those, respectively, into bodies, which, in turn, are combined into systems and must interact harmoniously with each other.
Tissue and organ levels of organization - study the sciences:
5. Organism level
Includes all previous levels: molecular, cellular,tissue levels and organ.
At this level, Living Nature is divided into kingdoms — animals, plants, and fungi.
Characteristics of this level:
- Metabolism (both at the level of the body and at the cellular level too)
- The structure (morphology) of the body
- Nutrition (metabolism and energy)
- homeostasis
- reproduction
- Interaction between organisms (competition, symbiosis, etc.)
- Interaction with the environment
Science:
6. Population-species level of life organization
Includes molecular, cellular,tissue levels, organ and body.
If several organisms are morphologically similar (in other words, have the same structure), and have the same genotype, then they form one species or population.
The main processes at this level are:
- The interaction of organisms with each other (competition or reproduction)
- microevolution (change of an organism under the influence of external conditions)
The world of wildlife is a collection of biological systems different levels organization and different subordination. They are in constant interaction. There are several levels of living matter:
Molecular- any living system, no matter how complex it is organized, manifests itself at the level of functioning of biological macromolecules: nucleic acids, proteins, polysaccharides, as well as important organic substances. From this level, the most important processes of the life of the organism begin: metabolism and energy conversion, transmission of hereditary information, etc. - the most ancient level of the structure of living nature, bordering on inanimate nature.
Cellular- a cell is a structural and functional unit, also a unit of reproduction and development of all living organisms living on Earth. There are no non-cellular life forms, and the existence of viruses only confirms this rule, since they can exhibit the properties of living systems only in cells.
Tissue- Tissue is a collection of cells similar in structure, united by the performance of a common function.
Organ- in most animals, an organ is a structural and functional combination of several types of tissues. For example, human skin as an organ includes epithelium and connective tissue, which together perform a number of functions, among which the most significant is protective.
Organismic- a multicellular organism is an integral system of organs specialized to perform various functions. Differences between plants and animals in the structure and methods of nutrition. The relationship of organisms with the environment, their adaptability to it.
population-species- a set of organisms of the same species, united by a common habitat, creates a population as a system of a supra-organismal order. In this system, the simplest, elementary evolutionary transformations are carried out.
Biogeocenotic- biogeocenosis - a set of organisms of different species and varying complexity of organization, all environmental factors.
biospheric The biosphere is the highest level of organization of living matter on our planet, including all life on Earth. Thus, living nature is a complexly organized hierarchical system.
2. Reproduction at the cellular level, mitosis and its biological role
Mitosis (from Greek mitos - thread), a type of cell division, as a result of which daughter cells receive genetic material identical to that contained in the mother cell. Karyokinesis, indirect cell division, is the most common method of cell reproduction (reproduction), which ensures the identical distribution of genetic material between daughter cells and the continuity of chromosomes in a number of cell generations.
Rice. 1. Scheme of mitosis: 1, 2 - prophase; 3 - prometaphase; 4 - metaphase; 5 - anaphase; 6 - early telophase; 7 - late telophase
The biological significance of mitosis is determined by the combination of the doubling of chromosomes in it by means of their longitudinal splitting and uniform distribution between daughter cells. The onset of mitosis is preceded by a period of preparation, including the accumulation of energy, the synthesis of deoxyribonucleic acid (DNA), and the reproduction of centrioles. The source of energy is rich in energy, or the so-called macroergic compounds. Mitosis is not accompanied by an increase in respiration, because oxidative processes occur in interphase (filling the "energy reserve of the macaw"). Periodic filling and emptying of the energy reserve of the macaw is the basis of the energy of mitosis.
The stages of mitosis are as follows. Single process. Mitosis is usually divided into 4 stages: prophase, metaphase, anaphase, and telophase.
Rice. Fig. 2. Mitosis in the meristematic cells of the onion root (micrograph). Interphase
Rice. Fig. 3. Mitosis in the meristematic tufts of the onion root (micrograph). Prophase (loose tangle figure)
Rice. 4. Mitosis in the meristematic cells of the onion root (micrograph). Late prophase (destruction of the nuclear envelope)
METAPHASE - consists in the movement of CHROMOSOMES to the equatorial plane (metakinesis, or prometaphase), the formation of the equatorial PLATE ("mother star") and in the separation of chromatids, or sister chromosomes.
Rice. Fig. 5. Mitosis in the meristematic cells of the onion root (micrograph). prometaphase
Fig.6. Mitosis in the meristematic cells of the onion root (micrograph). metaphase
Rice. Fig. 7. Mitosis in the meristematic cells of the onion root (micrograph). Anaphase
Anaphase - the stage of divergence of chromosomes to the poles. Anaphase movement is associated with the elongation of the central filaments of VERETIN, which pushes the mitotic poles apart, and with the shortening of the chromosomal MICROTUBES of the mitotic apparatus. The elongation of the central filaments of the SPINDLE occurs either due to the POLARIZATION of "reserve macromolecules" that complete the construction of the MICROTUBES of the spindle, or due to the dehydration of this structure. The shortening of chromosomal microtubules is provided by the PROPERTIES of the contractile proteins of the mitotic apparatus, which are capable of contraction without thickening. TELOPHASE - consists in the reconstruction of daughter nuclei from chromosomes gathered at the poles, the division of the cell body (CYTOTHYMIA, CYTOKINESIS) and the final destruction of the mitotic apparatus with the FORMATION of an intermediate body. Reconstruction of daughter nuclei is associated with chromosome desperalization, RESTORATION of the nucleolus and nuclear envelope. Cytotomy is carried out by the formation of a cell plate (in a plant cell) or by the formation of a fission furrow (in an animal cell).
Fig.8. Mitosis in the meristematic cells of the onion root (micrograph). Early telophase
Rice. Fig. 9. Mitosis in the meristematic cells of the onion root (micrograph). late telophase
The mechanism of cytotomy is associated either with the contraction of the gelatinized ring of the CYTOPLASMA encircling the EQUATOR (the "contractile ring" hypothesis) or with the expansion of the cell surface due to the straightening of the loop-like protein chains (the "MEMBRANE expansion" hypothesis).
Mitosis duration- depends on the size of the cells, their ploidy, the number of nuclei, as well as on the conditions environment, in particular on temperature. Mitosis lasts 30–60 minutes in animal cells, and 2–3 hours in plant cells. Longer stages of mitosis associated with the processes of synthesis (preprophase, prophase, telophase) self-movement of chromosomes (metakinesis, anaphase) is carried out quickly.
THE BIOLOGICAL SIGNIFICANCE OF MITOSIS - the constancy of the structure and the correct functioning of the organs and tissues of a multicellular organism would be impossible without the preservation of the same set of genetic material in countless cell generations. Mitosis provides important manifestations of vital activity: embryonic development, growth, restoration of organs and tissues after damage, maintenance of the structural integrity of tissues with constant loss of cells in the course of their functioning (replacement of dead erythrocytes, skin cells, intestinal epithelium, etc.) In protozoa, mitosis provides asexual reproduction.
3. Gametogenesis, characterization of germ cells, fertilization
Sex cells (gametes) - male spermatozoa and female eggs (or eggs) develop in the sex glands. In the first case, the path of their development is called SPERMATOGENESIS (from the Greek sperm - seed and genesis - origin), in the second - OVOGENESIS (from Latin ovo - egg)
Gametes are sex cells, their participation in fertilization, the formation of a zygote (the first cell of a new organism). The result of fertilization is the doubling of the number of chromosomes, the restoration of their diploid set in the zygote. Features of gametes are a single, haploid set of chromosomes compared to the diploid set of chromosomes in body cells2. Stages of development of germ cells: 1) increase by mitosis in the number of primary germ cells with a diploid set of chromosomes, 2) growth of primary germ cells, 3) maturation of germ cells.
STAGES OF GAMETOGENESIS - in the process of development of sexual both spermatozoa and eggs, stages are distinguished (fig.). The first stage is the period of reproduction, in which the primary germ cells divide by mitosis, as a result of which their number increases. During spermatogenesis, the reproduction of primary germ cells is very intensive. It begins with the onset of puberty and proceeds throughout the entire reproductive period. Reproduction of female primary germ cells in lower vertebrates continues almost all life. In humans, these cells multiply with the greatest intensity only in the prenatal period of development. After the formation of the female sex glands - the ovaries, the primary germ cells stop dividing, most of of them dies and resolves, the rest remain dormant until puberty.
The second stage is the period of growth. In immature male gametes, this period is expressed unsharply. The sizes of male gametes increase slightly. On the contrary, future eggs - oocytes sometimes increase hundreds, thousands and even millions of times. In some animals, oocytes grow very quickly - within a few days or weeks, in others, growth continues for months and years. The growth of oocytes is carried out due to substances formed by other cells of the body.
The third stage is the period of maturation, or meiosis (Fig. 1).
Rice. 9. Scheme of the formation of germ cells
Cells entering the period of meiosis contain a diploid set of chromosomes and already double the amount of DNA (2n 4c).
In the process of sexual reproduction, organisms of any species from generation to generation retain their characteristic number of chromosomes. This is achieved by the fact that before the fusion of germ cells - fertilization - in the process of maturation, the number of chromosomes decreases (reduces) in them, i.e. from a diploid set (2n) a haploid set (n) is formed. The patterns of meiosis in male and female germ cells are essentially the same.
Bibliography
- Currently, there are several levels of organization of living organisms: molecular, cellular, tissue, organ, organism, population-species, biogeocenotic and biospheric.
- At the population-species level, elementary evolutionary transformations are carried out.
- The cell is the most elementary structural and functional unit of all living organisms.
- A set of cells and intercellular substances similar in origin, structure and functions forms a tissue.
- The totality of all living organisms on the planet and their common natural habitat constitutes the biospheric level.
- List the levels of organization in order.
- What is fabric?
- What are the main parts of a cell?
- What organisms are characterized by the tissue level?
- Describe the organ level.
- What is a population?
- Describe the organism level.
- Name the features of the biogeocenotic level.
- Give examples of the interconnectedness of the levels of organization of life.
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Which is characterized by an organization with a clear hierarchy. It is this property that reflects the so-called levels of organization of life. In such a system, all parts are clearly arranged, starting from the lowest order to the highest.
The levels of life organization are a hierarchical system with subordinate orders, which reflects not only the nature of biosystems, but also their gradual complication in relation to each other. To date, it is customary to distinguish eight main levels
In addition, the following systems of organization are distinguished:
1. A microsystem is a kind of pre-organismal stage, which includes molecular and subcellular levels.
2. The mesosystem is the next, organismic stage. These include cellular, tissue, organ, systemic and organismic levels of life organization.
There are also macrosystems, which are a supra-organismal set of levels.
It is also worth noting that each level has its own characteristics, which will be discussed below.
Preorganismal levels of life organization
There are two main steps here:
1. Molecular level of life organization - represents the level of work and organization of biological macromolecules, including proteins, nucleic acids, lipids and polysaccharides. It is here that the most important life processes of any organism begin - cellular respiration, energy conversion, as well as the transfer of genetic information.
2. Subcellular level - this includes the organization of cell organelles, each of which plays an important role in the existence of the cell.
Organismal levels of life organization
This group includes those systems that ensure the holistic work of the whole organism. It is customary to single out the following:
1. Cellular level of life organization. It's no secret that the cell is the structural unit of any This level is studied using cytological, cytochemical, cytogenetic and
2. Tissue level. Here, the main attention should be paid to the structure, features and functioning of various kinds of tissues, of which, in fact, organs are composed. These structures are studied by histology and histochemistry.
3. Organ level. characterized by a new level of organization. Here, some groups of tissues are combined to form an integral structure with specific functions. Each organ is part of a living organism, but cannot independently exist outside of it. This level is studied by such sciences as physiology, anatomy and, to some extent, embryology.
Organism level are both unicellular and multicellular organisms. After all, each organism is an integral system within which all processes important for life are carried out. In addition, the processes of fertilization, development and growth, as well as the aging of an individual organism are taken into account. The study of this level is carried out by such sciences as physiology, embryology, genetics, anatomy, paleontology.
Supraorganismal levels of life organization
Here, it is no longer organisms and their structural parts that are taken into account, but a certain set of living beings.
1. Population-species level. The basic unit here is the population - a set of organisms of a certain species that inhabits a clearly defined area. All individuals are capable of free interbreeding with each other. Such sciences as taxonomy, ecology, population genetics, biogeography, taxonomy participate in the study of this level.
2. Ecosystem level- here, a stable community of different populations is taken into account, the existence of which is closely related to each other and depends on climatic conditions, etc. Ecology is mainly studying this level of organization
3. Biosphere level- this is highest form organization of life, which is a global complex of biogeocenoses of the entire planet.
All living organisms in nature consist of the same levels of organization; this is a characteristic biological pattern common to all living organisms.
The following levels of organization of living organisms are distinguished - molecular, cellular, tissue, organ, organism, population-species, biogeocenotic, biospheric.
Rice. 1. Molecular genetic level
1. Molecular genetic level. This is the most elementary level characteristic of life (Fig. 1). No matter how complex or simple the structure of any living organism, they all consist of the same molecular compounds. An example of this is nucleic acids, proteins, carbohydrates and other complex molecular complexes of organic and inorganic substances. They are sometimes called biological macromolecular substances. At the molecular level, there various processes life of living organisms: metabolism, energy conversion. With the help of the molecular level, the transfer of hereditary information is carried out, individual organelles are formed and other processes occur.
Rice. 2. Cellular level
2. Cellular level. The cell is the structural and functional unit of all living organisms on Earth (Fig. 2). Individual organelles in the cell have a characteristic structure and perform a specific function. The functions of individual organelles in the cell are interconnected and perform common life processes. In unicellular organisms (unicellular algae and protozoa), all life processes take place in one cell, and one cell exists as a separate organism. Remember unicellular algae, chlamydomonas, chlorella and protozoa - amoeba, infusoria, etc. In multicellular organisms, one cell cannot exist as a separate organism, but it is an elementary structural unit of the organism.
Rice. 3. Tissue level
3. Tissue level. A set of cells and intercellular substances similar in origin, structure and functions forms a tissue. The tissue level is typical only for multicellular organisms. Also, individual tissues are not an independent integral organism (Fig. 3). For example, the bodies of animals and humans are made up of four different tissues (epithelial, connective, muscle, and nervous). Plant tissues are called: educational, integumentary, supporting, conductive and excretory. Recall the structure and functions of individual tissues.
Rice. 4. Organ level
4. Organ level. In multicellular organisms, the union of several identical tissues, similar in structure, origin, and functions, forms the organ level (Fig. 4). Each organ contains several tissues, but among them one is the most significant. A separate organ cannot exist as a whole organism. Several organs, similar in structure and function, unite to form an organ system, for example, digestion, respiration, blood circulation, etc.
Rice. 5. Organism level
5. Organism level. Plants (chlamydomonas, chlorella) and animals (amoeba, infusoria, etc.), whose bodies consist of one cell, are an independent organism (Fig. 5). A separate individual of multicellular organisms is considered as a separate organism. In each individual organism, all the vital processes characteristic of all living organisms take place - nutrition, respiration, metabolism, irritability, reproduction, etc. Each independent organism leaves behind offspring. In multicellular organisms, cells, tissues, organs and organ systems are not a separate organism. Only complete system organs specialized in performing various functions forms a separate independent organism. The development of an organism, from fertilization to the end of life, takes a certain period of time. This individual development of each organism is called ontogeny. An organism can exist in close relationship with the environment.
Rice. 6. Population-species level
6. Population-species level. A set of individuals of one species or group that exists for a long time in a certain part of the range relatively apart from other sets of the same species constitutes a population. At the population level, the simplest evolutionary transformations are carried out, which contributes to the gradual emergence of a new species (Fig. 6).
Rice. 7 Biogeocenotic level
7. Biogeocenotic level. The totality of organisms of different species and varying complexity of organization, adapted to the same conditions natural environment, is called biogeocenosis, or natural community. The composition of biogeocenosis includes numerous types of living organisms and environmental conditions. In natural biogeocenoses, energy is accumulated and transferred from one organism to another. Biogeocenosis includes inorganic, organic compounds and living organisms (Fig. 7).
Rice. 8. Biosphere level
8. Biosphere level. The totality of all living organisms on our planet and their common natural habitat constitutes the biospheric level (Fig. 8). At the biospheric level, modern biology decides global problems, for example, determining the intensity of formation of free oxygen vegetation cover Earth or changes in the concentration of carbon dioxide in the atmosphere associated with human activities. main role at the biospheric level, "living substances" perform, that is, the totality of living organisms that inhabit the Earth. Also at the biospheric level, "bio-inert substances" are important, formed as a result of the vital activity of living organisms and "inert" substances (i.e., environmental conditions). At the biospheric level, the circulation of substances and energy on Earth takes place with the participation of all living organisms of the biosphere.
levels of organization of life. population. Biogeocenosis. Biosphere.
Complete the table showing the structural features of each level of the organization:
| Serial number |
Organization levels |
Peculiarities |
