Organization levels living systems reflect subordination, hierarchy structural organization life; differ from each other in the complexity of the organization of the system (the cell is simpler in comparison with a multicellular organism or population).

Standard of living - this is a form and a way of its existence (a virus exists in the form of a DNA or RNA molecule enclosed in a protein shell - a form of a virus's existence. However, a virus exhibits the properties of a living system only when it gets into a cell of another organism, where it multiplies - a way of its existence).

THEMATIC ASSIGNMENTS

Part A

A1. The level at which the processes of biogenic migration of atoms are studied is called:

1) biogeocenotic
2) biosphere
3) population-specific
4) molecular genetic

A2. At the population-species level, they study:

1) gene mutations
2) the relationship of organisms of the same species
3) organ systems
4) metabolic processes in the body

A3. Maintaining relative consistency chemical composition organism is called

1) metabolism
2) assimilation
3) homeostasis
4) adaptation

A4. The occurrence of mutations is associated with such a property of the organism as

1) heredity
2) variability
3) irritability
4) self-reproduction

A5. Which of the listed biological systems forms the most high level life?

1) amoeba cell
2) smallpox virus
3) a herd of deer
4) nature reserve

A6. Taking a hand off a hot object is an example

1) irritability
2) the ability to adapt
3) inheritance of traits from parents
4) self-regulation

A7. Photosynthesis, protein biosynthesis are examples

1) plastic metabolism
2) energy metabolism
3) nutrition and respiration
4) homeostasis

A8. Which of the terms is synonymous with the concept of "metabolism"?

1) anabolism
2) catabolism
3) assimilation
4) metabolism

Part B

IN 1. Select the processes studied at the molecular genetic level of life:

1) DNA replication
2) inheritance of Down's disease
3) enzymatic reactions
4) the structure of mitochondria
5) the structure of the cell membrane
6) blood circulation

IN 2. Correlate the nature of adaptation of organisms with the conditions to which they were developed

Part C

C1. What adaptations of plants provide them with reproduction and dispersal?
C2. What is common and what are the differences between different levels of organization of life?

By the 1960s. in biology there is an idea about the levels organization of living things as a concrete expression of the increasingly complex orderorganic world. Life on Earth is represented by organisms of a kindbuildings belonging to certain systematic groups (species), as well ascommunities of varying complexity (biogeocenosis, biosphere). In turn, organismscharacterized by organ, tissue, cellular and molecular organization.Each organism, on the one hand, consists of specialized subordinatessystems of organization (organs, tissues, etc.), on the other hand, it is itselfrelatively isolated unit in the composition of supraorganism biologicalsystems (species, biogeocenoses and biosphere as a whole). Organization levels livematter are shown in Fig. one

Fig. 1. Organizational levels of the living

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

Table 1

Characteristics of the levels of organization of the living

The world of living nature is a collection of biological systems different levels organization and various subordination. They are in continuous 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 vital processes 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 that live on Earth. There are no cellular life forms, but the existence of viruses only confirms this rule, since they can manifest 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 association of several types of tissues. For example, human skin as an organ includes epithelium and connective tissue, which together perform whole line functions among which the most significant is protective.

Organic- a multicellular organism is an integral system of organs specialized to perform various functions. Differences between plants and animals in structure and nutrition. The relationship of organisms with the environment, their adaptability to it.

Population-specific- a set of organisms of the same total species, united by a common habitat, creates a population as a system of a supraorganismic order. In this system, the simplest, elementary evolutionary transformations are carried out.

Biogeocenotic- biogeocenosis - a set of organisms of different types and varying complexity of organization, all factors of the environment.

Biosphere- the biosphere is the highest level of organization of living matter on our planet, including all life on Earth. Thus, wildlife is a complexly organized hierarchical system.

2. Reproduction at the cellular level, mitosis and its biological role

Mitosis (from the 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 way of reproduction (reproduction) of cells, ensuring 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 chromosome duplication in it through their longitudinal splitting and uniform distribution between daughter cells. The onset of mitosis is preceded by a preparatory period that includes energy storage, synthesis of deoxyribonucleic acid (DNA), and reproduction of centrioles. The source of energy is energy-rich, or so-called high-energy compounds. Mitosis is not accompanied by increased respiration, since oxidative processes occur in the interphase (filling the "energy reservoir"). Periodic filling and emptying of the energy reserve of ara is the basis of the energy of mitosis.

The stages of mitosis are as follows. One process. Mitosis is usually divided into 4 stages: prophase, metaphase, anaphase, and telophase.

Rice. 2. Mitosis in the meristematic cells of the onion root (micrograph). Interphase

Rice. 3. Mitosis in the meristematic clays of the onion root (photomicrograph). Prophase (the figure of a loose ball)

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 CHROMOSOM to the equatorial plane (metakinesis, or prometaphase), the formation of an equatorial PLATE ("mother star") and in the separation of chromatids, or sister chromosomes.

Rice. 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. 7. Mitosis in the meristematic cells of the onion root (micrograph). Anaphase

ANAPHASE - the stage of the divergence of chromosomes to the poles. Anaphase movement is associated with the elongation of the central filaments of VERETIN, pushing the mitotic poles, and with the shortening of the chromosomal MICROTUBULES of the mitotic apparatus. Elongation of the central filaments of VERETENA occurs either due to the POLARIZATION of "spare macromolecules", completing the construction of the spindle MICROTUBES, 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, capable of contraction without thickening. TELOPHASE - consists in the reconstruction of daughter nuclei from chromosomes gathered at the poles, division of the cell body (CYTOTYMIA, 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 plant cell) or by the formation of a division furrow (in an animal cell).

Fig. 8. Mitosis in the meristematic cells of the onion root (micrograph). Early telophase

Rice. 9. Mitosis in the meristematic cells of the onion root (micrograph). Late telophase

The mechanism of cytotomy is associated either with a contraction of the gelled CYTOPLASM ring encircling the EQUATOR (the "contractible ring" hypothesis), or with the expansion of the cell surface due to the straightening of looped protein chains (the "MEMBRAN expansion" hypothesis)

Duration of mitosis- depends on the size of cells, their ploidy, the number of nuclei, as well as on environmental conditions, in particular on temperature. In animal cells, mitosis lasts 30-60 minutes, in plant cells 2-3 hours. Longer stages of mitosis associated with synthesis processes (preprophase, prophase, telophase) self-movement of chromosomes (metakinesis, anaphase) occurs quickly.

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 during their functioning (replacement of dead erythrocytes, emerging skin cells, intestinal epithelium, etc.) In protozoa, mitosis provides asexual reproduction.

3. Gametogenesis, characteristics of germ cells, fertilization

Sexual cells (gametes) - male sperm 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 a doubling of the number of chromosomes, restoration of their diploid set in the zygote. Features of gametes are a single, haploid set of chromosomes in comparison with the diploid set of chromosomes in body cells2. The 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 genital both sperm 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 the primary germ cells is very intense. It begins with the onset of puberty and continues throughout the reproductive period. Reproduction of female primary germ cells in lower vertebrates lasts almost all life. In humans, these cells multiply with the greatest intensity only in the intrauterine period of development. After the formation of the female sex glands - the ovaries, the primary sex cells stop dividing, most of they die and dissolve, the rest remain dormant until puberty.

The second stage is the growth period. In immature male gametes, this period is not sharply expressed. The size of male gametes increases slightly. On the contrary, future eggs - oocytes sometimes increase hundreds, thousands and even millions of times. In some animals, oocytes grow very quickly - within days or weeks; in other species, growth continues for months or years. The growth of oocytes is carried out at the expense of substances formed by other cells in the body.

The third stage is the maturation period, or meiosis (Figure 1).

Rice. 9. Scheme of formation of germ cells

Cells entering the period of meiosis contain a diploid set of chromosomes and already a doubled 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 the germ cells - fertilization - in the process of maturation, the number of chromosomes in them decreases (is reduced), i.e. from the diploid set (2n) a haploid set (n) is formed. The regularities of the passage of meiosis in male and female germ cells are essentially the same.

Bibliography

Gorelov A.A.Concepts of modern natural science. - M .: Center, 2008.


Dubnischeva T.Ya. and others. Modern natural science. - M .: Marketing, 2009.


Lebedeva N.V., Drozdov N.N., Krivolutskiy D.A. Biological diversity... M., 2004.


Mamontov S.G. Biology. M., 2007.


Yarygin V. Biology. M., 2006.


There are such levels of organization of living matter - levels of biological organization: molecular, cellular, tissue, organ, organismic, population-specific 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 by: biochemistry, molecular genetics, molecular biology, genetics, biophysics.

Cell 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, microbiology.

Tissue organization level- This is the level at which the structure and functioning of tissues is studied. This level is investigated by histology and histochemistry.

Organ level of organization- this is the level of organs of multicellular organisms. This level is studied by anatomy, physiology, embryology.

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

Population-specific level is the level of the 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 influence on the gene pool (microevolution), the problem of species conservation.

Ecosystem level of organization is the level of microecosystems, mesoecosystems, macroecosystems. At this level, the 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 is studied by ecology.

There are also biosphere level of organization living matter. The biosphere is a gigantic ecosystem that occupies part of the geographic shell of the Earth. It's a mega ecosystem. In the biosphere, there is a cycle of substances 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, the breakdown and synthesis of molecules that make up cells occurs; 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 in the course of dissimilation (as well as the accumulation of energy when synthesized substances are deposited into the supply). Dissimilation - the processes of splitting (anaerobic or aerobic) of complex organic compounds, going with the release of energy necessary for the implementation of the body's vital functions. Unlike bodies of inanimate nature, exchange with the environment for living organisms is a condition of 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 course of a large number of reactions in a small volume is achieved through the orderly distribution of individual metabolic links in the cell (the principle of compartmentalization). Metabolic processes are regulated by biocatalysts - special protein enzymes. Each enzyme has a 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 nonbiological 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 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 the necessary substances for their vital activity. Autotrophs - organisms synthesizing from inorganic substances organic compounds using the energy of sunlight (photosynthetics - green plants, algae, some bacteria) or energy obtained from the oxidation of an inorganic substrate (chemosynthetics - sulfur, iron bacteria and some others), Autotrophic organisms are able to synthesize all components of the cell. The role of photosynthetic autotrophs in nature is decisive - being the primary producer of organic matter in the biosphere, they ensure the existence of all other organisms and the course of 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, 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 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) 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 life span of an individual organism is limited. Reproduction more than compensates for the losses caused by 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, in the currently existing numerous and diverse species of living organisms, we find different shapes reproduction. Many types of organisms combine several methods of reproduction. It is necessary to single out two fundamentally different types of reproduction of organisms - asexual (primary and more ancient type 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 mother's body. In all forms of asexual reproduction, the offspring have a genotype (a 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, formed as a result of combining sets of chromosomes of merged gamete nuclei. Thus, in the nucleus of the zygote, a new combination of hereditary inclinations (genes), introduced equally by both parents, is created. And the daughter organism developing from the zygote will have a new combination of traits. 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 is an essential factor in evolution. This is the significant advantage of sexual reproduction over asexual. The ability of living organisms to reproduce itself 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 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. Reproduction of organisms ensures 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 (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 encoded in the molecular structure of DNA (in some viruses, in RNA). The genes encoded information about the structure of synthesized proteins, enzymatic and structural. A genetic code is a system for "recording" information about the sequence of amino acids in synthesized proteins using the sequence of nucleotides in a DNA molecule. The set of all genes of an organism is called the genotype, and the set of traits is called the phenotype. The phenotype depends on both the genotype and the factors of internal and external environment that influence 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 versatile. Thanks to heredity, traits are transmitted from generation to generation that ensure the adaptability of organisms to their habitat. If during the reproduction of organisms only the continuity of existing signs and properties were manifested, then against the background of changing conditions of the external environment, the existence of organisms would be impossible, since a necessary condition for the life of organisms is their adaptation to environmental conditions. Variability is manifested 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, which differ in the mechanisms of occurrence, the nature of changes in traits 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. Genotypic variability can be based on mutations (mutational variability) or new combinations of genes that arise during fertilization during sexual reproduction. In the mutational form, the changes are associated primarily with errors in the replication of nucleic acids. Thus, the emergence of new genes that carry new genetic information occurs; new signs appear. And if the newly emerging traits are useful to the body in specific conditions, then they are "picked up" and "fixed" by natural selection. Thus, the adaptability of organisms to environmental conditions, a variety of organisms is 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 characters 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 significance of modification variability lies in the fact that it ensures the organism's adaptability to environmental factors during its life.

Individual development of organisms

All living organisms are characterized by the 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 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 a "genetic program" (embedded in the genes of the chromosomes of the zygote) and is carried out in specific environmental conditions, which significantly affects the process of realization of genetic information during the individual existence of an individual. On the early stages individual development, intensive growth (increase in mass and size) occurs, due to the reproduction of molecules, cells and other structures, and differentiation, i.e. the appearance of differences in the structure and the 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 effect 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, increasing as the anthropogenic impact on nature intensifies. In various fields of biology, medicine, veterinary medicine and other sciences, studies are widely carried out to study the processes of normal and pathological development of organisms, 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 (influences) and adequately respond to them. In organisms, irritability is accompanied by a complex of changes expressed in metabolic shifts, 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 is 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 in 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, underlies the biosynthesis of macromolecules. Genome replication corresponds to the informational transition DNA → DNA. 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 transmission into three groups:

Common - found in most living organisms;

Special - occurring as an exception, in viruses and at mobile elements of the genome or in a biological experiment;

Unknown - not found.

DNA replication (DNA → DNA)

DNA is the main way of transferring information between generations of living organisms, therefore 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 that, DNA polymerase and 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 piece of DNA is copied to the synthesized molecule messenger RNA... Transcription is carried out transcription factors and RNA polymerase... V eukaryotic cell the primary transcript (pre-mRNA) is often edited. This process is called splicing.

Translation (RNA → protein)

Mature mRNA is read ribosomes in the process of broadcasting. V prokaryotic cells, the process of transcription and translation is not spatially separated, and these processes are coupled. V eukaryotic cells of the place of transcription cell nucleus separated from the broadcast location ( cytoplasm) nuclear membrane, therefore, mRNA transported from the core into the cytoplasm. mRNA is read by the ribosome in the form of three nucleotide"Words". Complexes initiation factors and elongation factors deliver aminoacylated transport RNA to the mRNA-ribosome complex.

5. Reverse transcription is the process of formation of 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", relative to transcription, direction.

The idea of ​​reverse transcription was initially very unpopular, as it contradicted central dogma of molecular biology which suggested that DNA transcribed in RNA and beyond broadcasted into proteins. Occurs in retroviruses, For example, Hiv and in case retrotransposons.

Transduction(from lat. transductio- moving) - transfer process bacterial DNA from one cell to another bacteriophage... General transduction is used in bacterial genetics for genome mapping and design strains... Both temperate and virulent phages are capable of transduction, the latter, however, destroy the bacterial population, therefore transduction with their help does not have of great importance neither in nature, nor during research.

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

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

The presence of a selective marker

Availability of convenient restriction sites

Bacterial plasmids most often act as vectors.

LEVELS OF ORGANIZATION OF LIFE

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 lawful relationships and connections with each other. The main biological categories, such as genome (genotype), cell, organism, population, biogeocenosis, biosphere, are systems. A hierarchical called a system in which parts, or elements, are arranged in order from lowest to highest. So, 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 makes it possible to single out individual levels, which is convenient from the point of view of studying life as a complex natural phenomenon.

In biomedical science, it is widely used level classification in accordance with the most important parts, structures and components of the body, which are direct objects of study for researchers of different specialties. Such objects can be an organism as such, organs, tissues, cells, intracellular structures, molecules. The selection of the levels of the considered classification is in good agreement with the resolving power of the methods used by biologists and doctors: the study of an object with the naked eye, using a magnifying glass, light-optical microscope, electron microscope, modern physical and chemical methods. The connection between these levels and the typical sizes of the studied biological objects is obvious (Table 1.1).

Table 1.1. The level of organization (study), allocated in a multicellular organism (according to E. Ds. Roberts et al., 1967, with changes)

The interpenetration of ideas and methods of various areas of natural science (physics, chemistry, biology), the emergence of sciences at the junction of these areas (biophysics, biochemistry, molecular biology) led to the expansion of the classification, up to the allocation of molecular and electron-atomic levels. Biomedical research carried out at these levels is already giving a practical outlet in health care. Thus, devices based on the phenomena of electronic paramagnetic and nuclear magnetic resonance are successfully used to diagnose diseases and conditions of the body.

The ability to investigate fundamental biological processes in the body at the cellular, subcellular and even molecular levels is outstanding, but not the only one. hallmark modern biology. Typical of her is a deep interest in the processes in the communities of organisms that determine the planetary role of life.

Thus, the classification was supplemented by supraorganismic levels, such as species, biogeocenotic, and biospheric.

Most of the specific biomedical and anthropobiological sciences adhere to the above classification. This is not surprising, since it reflects the levels of organization of living nature through the historically established levels of its study. The task of the course of biology of a medical university is to teach the most full description biological "inheritance" of people. To solve this problem, it is advisable to use the classification that most closely reflects precisely levels of organization of life.

In the named classification, molecular-genetic, cellular, organismic, or ontogenetic, population-species, biogeocenotic levels are distinguished. The peculiarity of this classification lies in the fact that the individual levels of the hierarchical system of life are determined 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 the preservation and development of life. The correspondence of the allocated levels to the nodal 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 for molecular genetic level serves as a gene - a fragment of a nucleic acid molecule, in which a quantity of biological (genetic) information determined in a qualitative and quantitative relation is recorded. An elementary phenomenon lies primarily in the process constant reduplication, or self-reproduction, with the possibility of some changes in the content of the information encoded in the gene. By means of DNA reduplication, the biological information contained in genes is copied, which ensures the continuity and preservation (conservatism) of the properties of organisms in a number of generations. Reduplication is thus the basis of heredity.

Due to the limited stability of molecules or synthesis errors in DNA (from time to time, but inevitably), abnormalities occur that alter the information of the genes. In the subsequent DNA replication, these changes are reproduced in copy molecules and inherited by organisms of the daughter generation. These changes arise and replicate naturally, which makes DNA reduplication constant, i.e. sometimes with some changes. Such changes in genetics are called gene(or true) mutations. The reduplication convariance thus serves as the basis for mutational variability.

The biological information contained in DNA molecules is not directly involved in life processes. It transforms into an active form, being transferred into protein molecules. The marked transfer is carried out thanks to the mechanism matrix synthesis, in which the original DNA serves, as in the case of reduplication, a template (form), but for the formation of not a daughter DNA molecule, but a messenger RNA that controls the biosynthesis of proteins. The abovementioned gives reason to classify the matrix synthesis of information macromolecules as an elementary phenomenon at the molecular-genetic level of the organization of life.





The embodiment of biological information in specific life processes requires special structures, energy and various chemical substances(substrates). The conditions described above in living nature are provided by a cell serving as an elementary structure cellular level. An elementary phenomenon is presented reactions of cellular metabolism, constituting the basis of the flows of energy, substances and information. Due 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 conversion 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 organism / that level is an individual in its development from the moment of inception to the termination of existence as a living system, which also allows us to call this level ontogenetic. Natural changes in the body individual development constitute an elementary phenomenon of 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. In the course of ontogenesis, under certain environmental conditions, the hereditary information is embodied in biological structures and processes; on the basis of the genotype, the phenotype of organisms of this species is formed.

Elementary unit population-species level serves population - a set 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 the genotypes of individuals of the next generation. The population, due to the possibility of interpopulation crosses, 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 evolutionary meaningful changes gene pool, which represent elementary phenomena at a given level.

Organisms of one species inhabit an area with known abiotic parameters (climate, soil chemistry, hydrological conditions) and interact with organisms of other species. In the process of joint historical development on a certain territory of organisms of different systematic groups, dynamic, time-stable communities are formed - biogeocenoses, which serve as an elementary unit biogeocenotic(ecosystem) level. An elementary phenomenon at the considered level is represented by flows of energy and circulation of substances. The leading role in these cycles and flows belongs to living organisms. Biogeocenosis is a system open in material and energy terms. Biogeocenoses, differing in the 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 distinguished 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 heredity phenomena and true mutational variability are associated with convariant reduplication at the molecular genetic level. Special role the cellular level consists of energy, material and information support happening at all other levels. At the ontogenetic level, the biological information in the genes is converted into a complex of characteristics and properties of the organism. The resulting phenotype 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 in the formation of communities of organisms of different species, adapted to cohabitation in a particular habitat. An important distinguishing feature of such communities is their stability over time.

The levels considered reflect general structure evolutionary process, the natural result of which is a person. Therefore, the elementary structures and phenomena typical for these levels apply to people, albeit with some peculiarities due to their social essence.