Biology in the practical activities of people. The role of biology in human life and practical activities

There are a lot of ways in which a person can use knowledge in biology; for example, here are a few (let’s go from largest to smallest):

· Knowledge environmental laws allows you to regulate human activity within the limits of preserving the ecosystem in which he lives and works (rational environmental management);

· Botany and genetics allow you to increase productivity, fight pests and develop new, necessary and useful varieties;

· Genetics is currently so tightly intertwined with medicine that many diseases that were previously considered incurable are studied and prevented already at the embryonic stages of human development;

· With the help of microbiology, scientists around the world are developing serums and vaccines against viruses and a wide variety of antibacterial drugs.

Differences between living structures and nonliving ones. Properties of living things

Biology - a science that studies the properties of living systems. However, defining what a living system is is quite difficult. The line between living and nonliving is not as easy to draw as it seems. Try to answer the questions: Are viruses alive when they rest outside the host’s body and do not undergo metabolism? Can artificial objects and machines exhibit the properties of living things? What about computer programs? Or languages?

To answer these questions, we can try to isolate a minimum set of properties characteristic of living systems. That is why scientists have established several criteria by which an organism can be classified as living.

The most important of characteristic properties (criteria) of living things are the following:

1. Exchange of matter and energy with the environment. From the point of view of physics, all living systems are open, that is, they constantly exchange both matter and energy with the environment, unlike closed completely isolated from the outside world, and semi-closed, exchanging only energy, but not matter. We will see later that this exchange is a prerequisite for the existence of life.

2. Living systems are capable of accumulating substances received from the environment and, as a result, growth.

3. Modern biology considers the fundamental property of living beings to be the ability to create identical (or almost identical) self-reproduction, that is, reproduction while maintaining most of the properties of the original organism.

4. Identical self-reproduction is inextricably linked with the concept heredity, that is, the transmission of traits and properties to offspring.

5. However, heredity is not absolute - if all daughter organisms exactly copied their parents, then no evolution would be possible, since living organisms would never change. This would lead to the fact that with any sudden change in conditions they would all die. But life is extremely flexible, and organisms adapt to a wide range of conditions. This is possible thanks to variability– the fact that the self-reproduction of organisms is not completely identical; during it, errors and variations arise, which can be material for selection. There is a certain balance between heredity and variability.

6. Variability can be hereditary and non-hereditary. Hereditary variability, that is, the appearance of new variations of traits that are inherited and fixed in a number of generations, serves as material for natural selection. Natural selection is possible among any reproducing objects, not necessarily living ones, if there is competition between them for limited resources. Those objects that, due to variability, have acquired unfavorable characteristics in a given environment will be rejected, therefore, characteristics that give a competitive advantage in the fight will be found more and more often in new objects. This is natural selection - the creative factor of evolution, thanks to which all the diversity of living organisms on Earth arose.

7. Living organisms actively respond to external signals, exhibiting the property irritability.

8. Thanks to their ability to respond to changes in external conditions, living organisms are capable of adaptation- adaptation to new conditions. This property, in particular, allows organisms to survive various disasters and spread to new territories.

9. Adaptation is carried out by self-regulation, that is, the ability to maintain the constancy of certain physical and chemical parameters in a living organism, including in changing environmental conditions. For example, the human body maintains a constant temperature, concentration of glucose and many other substances in the blood.

10. An important property of earthly life is discreteness, that is, discontinuity: it is represented by individual individuals, individuals are combined into populations, populations into species, etc., that is, at all levels of organization of living things there are separate units. Stanislaw Lem's science fiction novel Solaris describes a huge living ocean covering the entire planet. But there are no such life forms on Earth.

Chemical composition of living things

Living organisms consist of a huge number of chemical substances, organic and inorganic, polymeric and low molecular weight. Many chemical elements present in the environment are found in living systems, but only about 20 of them are necessary for life. These elements are called biogenic.

In the process of evolution from inorganic to bioorganic substances, the basis for the use of certain chemical elements in the creation of biological systems is natural selection. As a result of this selection, the basis of all living systems consists of only six elements: carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur, called organogens. Their content in the body reaches 97.4%.

Organogens are the main chemical elements that make up organic substances: carbon, hydrogen, oxygen and nitrogen.

From the point of view of chemistry, the natural selection of organogen elements can be explained by their ability to form chemical bonds: on the one hand, quite strong, that is, energy-intensive, and on the other, quite labile, which could easily succumb to hemolysis, heterolysis, and cyclic redistribution.

The number one organogen is undoubtedly carbon. Its atoms form strong covalent bonds with each other or with atoms of other elements. These bonds can be single or multiple; thanks to these 3 bonds, carbon is able to form conjugated or cumulated systems in the form of open or closed chains and cycles.

Unlike carbon, the organogenic elements hydrogen and oxygen do not form labile bonds, but their presence in an organic, including bioorganic, molecule determines its ability to interact with a biosolvent—water. In addition, hydrogen and oxygen are carriers of the redox properties of living systems; they ensure the unity of redox processes.

The remaining three organogens - nitrogen, phosphorus and sulfur, as well as some other elements - iron, magnesium, which constitute the active centers of enzymes, like carbon, are capable of forming labile bonds. A positive property of organogens is also that they, as a rule, form compounds that are easily soluble in water and therefore concentrate in the body.

There are several classifications of chemical elements contained in the human body. Thus, V.I. Vernadsky, depending on the average content in living organisms, divided the elements into three groups:

1. Macroelements. These are elements whose content in the body is higher than 10 - ²%. These include carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur, calcium, magnesium, sodium and chlorine, potassium, and iron. These are the so-called universal biogenic elements present in the cells of all organisms.

2. Microelements. These are elements whose content in the body ranges from 10 - ² to 10 - ¹²%. These include iodine, copper, arsenic, fluorine, bromine, strontium, barium, and cobalt. Although these elements are contained in organisms in extremely low concentrations (not higher than a thousandth of a percent), they are also necessary for normal life. These are biogenic microelements. Their functions and roles are very diverse. Many microelements are part of a number of enzymes, vitamins, respiratory pigments, some affect growth, development rate, reproduction, etc.

3. Ultramicroelements. These are elements whose content in the body is below 10-¹²%. These include mercury, gold, uranium, radium, etc.

V.V. Kovalsky, based on the degree of importance of chemical elements for human life, divided them into three groups:

1. Irreplaceable elements. They are constantly present in the human body and are part of its inorganic and organic compounds. These are H, O, Ca, N, K, P, Na, S, Mg, Cl, C, I, Mn, Cu, Co, Zn, Fe, Mo, V. A deficiency in the content of these elements leads to disruption of the normal functioning of the body.

2. Impurity elements. These elements are constantly present in the human body, but their biological role has not yet always been clarified or has been poorly studied. These are Ga, Sb, Sr, Br, F, B, Be, Li, Si, Sn, Cs, As, Ba, Ge, Rb, Pb, Ra, Bi, Cd, Cr, Ni, Ti, Ag, Th, Hg , Ce, Se.

3. Microimpurity elements. They are found in the human body, but there is no information about their quantitative content or biological role. These are Sc, Tl, In, La, Sm, Pr, W, Re, Tb, etc. The chemical elements necessary for the construction and functioning of cells and organisms are called biogenic.

Among inorganic substances and components, the main place is occupied by - water.

To maintain the ionic strength and pH environment at which vital processes occur, certain concentrations of inorganic ions are necessary. To maintain a certain ionic strength and connection of the buffer medium, the participation of singly charged ions is necessary: ​​ammonium (NH4+); sodium(Na+); potassium (K+). Cations are not interchangeable; there are special mechanisms that maintain the necessary balance between them.

Inorganic compounds:

Ammonium salts;

Carbonates;

Sulfates;

Phosphates.

Nonmetals:

1. Chlorine (basic). In the form of anions, it participates in the creation of a salt environment, and is sometimes part of some organic substances.

2. Iodine and its compounds take part in some vital processes of organic compounds (living organisms). Iodine is part of the thyroid hormones (thyroxine).

3. Selenium derivatives. Selenocesteine ​​is part of some enzymes.

4. Silicon - is part of cartilage and ligaments, in the form of orthosilicic acid esters, takes part in the stitching of polysaccharide chains.

Many compounds in living organisms are complexes: heme is a complex of iron with a flat paraffin molecule; cobolamine

Magnesium and calcium are the main ones metals, not counting iron, are ubiquitous in biological systems. The concentration of magnesium ions is important for maintaining the integrity and functioning of ribosomes, that is, for protein synthesis.

Magnesium is also part of chlorophyll. Calcium ions take part in cellular processes including muscle contractions. Undissolved salts – participate in the formation of supporting structures:

Calcium phosphate (in bones);

Carbonate (in mollusk shells).

Metal ions of the 4th period are part of a number of vital compounds - enzymes. Some proteins contain iron in the form of iron-sulfur clusters. Zinc ions are found in a significant number of enzymes. Manganese is part of a small number of enzymes, but plays an important role in the biosphere, during the photochemical reduction of water, ensures the release of oxygen into the atmosphere and the supply of electrons to the transport chain during photosynthesis.

Cobalt is part of enzymes in the form of cobalamins (vitamin B 12).

Molybdenum is an essential component of the enzyme nitrodinase (which catalyzes the reduction of atmospheric nitrogen to ammonia in nitrogen-fixing bacteria)

Big number organic matter part of living organisms: acetic acid; acetaldehyde; ethanol (are products and substrates of biochemical transformations).

The main groups of low-molecular compounds of living organisms:

Amino acids are components of proteins

Nucleamides are part of nucleic acids

Mono and oligosaccharides are components of structural tissues

Lipids are components of cell walls.

In addition to the previous ones, there are:

Enzyme cofactors are essential components of a significant number of enzymes and catalyze redox reactions.

Coenzymes are organic compounds that function in certain enzyme reaction systems. For example: nicotinoamidodanine dinucleatide (NAD+). In oxidized form, it is an oxidizer of alcohol groups to carbonyl groups, thereby forming a reducing agent.

Enzyme cofactors are complex organic molecules synthesized from complex precursors that must be present as essential components of food.

Higher animals are characterized by the formation and functioning of substances that control the nervous and endocrine systems - hormones and neurotransmitters. For example, the adrenal hormone triggers the oxidative processing of glycogen during a stressful situation.

Many plants synthesize complex amines with strong biological effects - alkaloids.

Terpenes are compounds of plant origin, components of essential oils and resins.

Antibiotics are substances of microbiological origin, secreted by special types of microorganisms that suppress the growth of other competing microorganisms. Their mechanism of action is varied, for example slowing down the growth of proteins in bacteria.

MKOU"Novokaykent Secondary School"

With. Novokayakent

Kayakent district Republic of Dagestan

OGE. Task 1. “The role of biology in the formation of a modern natural science picture of the world, in the practical activities of people »

(for 9th grade students)

MKOU "Novokayakent Secondary School"

Umalatova Ravganiyat Biybulatovna

Novokayakent village

Explanatory note

This material is OGE. Questions 1. “The role of biology in the formation of a modern natural science picture of the world, in the practical activities of people” is recommended for 9th grade students. The material includes questions with a choice of one correct answer. This material can be used to prepare for the OGE. The work includes 12 questions.

Tasks: test students' knowledge and ability to correctly select one correct answer to a question.

Equipment: handouts with tests.

OGE. Questions 1.“The role of biology in the formation of the modern natural science picture of the world, in the practical activities of people »

1.Science studies the patterns of heredity and variability of organisms

1) genetics

2) taxonomy

3) anthropology

4) biochemistry

3.What science studies human health and ways to preserve it?

1) valeology

2) hygiene

3) medicine

4) physiology

5. Which of the following scientists is considered the founder of the science of genetics?

1) I.I. Mechnikov

2) L. Pasteur

3) G. Mendel

4) C. Darwin

7. The main way to study a plant cell is

1) observation

2) microscopy

3) freezing - chipping

4) coloring

9. The mechanism of protein biosynthesis in the body has been discovered

1) anatomists

2) physiologists

3) biochemists

4) ecologists

11. To put forward a hypothesis means

1) confirm the scientific nature of the data obtained

2) conduct an experiment

3) make a guess

4) summarize changing facts

Sources of information:

1.Biology. General patterns. 9th grade S.G. Mamontov, V.B. Zakharov, N.I. Sonin. -M.: Bustard, 2002, 288 p.

2. Biology Unified State Examination. Section "Plants, mushrooms, lichens". Theory, training tasks: educational manual / A.A. Kirilenko-

Rostov n/a: Legion, 2015 - 320 p.

3. OGE 2017. Biology: thematic training tasks: 9th grade/

G.I. Lerner.- Moscow: Eksmo, 2016.- 272 p.

4. OGE. Biology: standard exam options: O -30 options / ed. V.S. Rokhlova.-M.: Publishing house “National Education”, 2017.- 400 p.

Biology as a science

Biology(from Greek bios- life, logo- word, science) is a complex of sciences about living nature.

The subject of biology is all manifestations of life: the structure and functions of living beings, their diversity, origin and development, as well as interaction with the environment. The main task of biology as a science is to interpret all phenomena of living nature on a scientific basis, taking into account that the whole organism has properties that are fundamentally different from its components.

The term “biology” is found in the works of the German anatomists T. Roose (1779) and K. F. Burdach (1800), but only in 1802 was it first used independently by J. B. Lamarck and G. R. Treviranus to denote the science that studies living organisms.

Biological Sciences

Currently, biology includes a number of sciences that can be systematized according to the following criteria: by subject and predominant research methods and by the level of organization of living nature being studied. According to the subject of study, biological sciences are divided into bacteriology, botany, virology, zoology, and mycology.

Botany is a biological science that comprehensively studies plants and the Earth's vegetation cover. Zoology- a branch of biology, the science of the diversity, structure, life activity, distribution and relationship of animals with their environment, their origin and development. Bacteriology- biological science that studies the structure and vital activity of bacteria, as well as their role in nature. Virology- biological science that studies viruses. The main object of mycology is mushrooms, their structure and characteristics of life. Lichenology- biological science that studies lichens. Bacteriology, virology and some aspects of mycology are often considered as part of microbiology - a branch of biology, the science of microorganisms (bacteria, viruses and microscopic fungi). Systematics or taxonomy, is a biological science that describes and classifies into groups all living and extinct creatures.

In turn, each of the listed biological sciences is divided into biochemistry, morphology, anatomy, physiology, embryology, genetics and systematics (plants, animals or microorganisms). Biochemistry is the science of the chemical composition of living matter, the chemical processes occurring in living organisms and underlying their life activity. Morphology- biological science that studies the form and structure of organisms, as well as the patterns of their development. In a broad sense, it includes cytology, anatomy, histology and embryology. Distinguish between the morphology of animals and plants. Anatomy is a branch of biology (more precisely, morphology), a science that studies the internal structure and shape of individual organs, systems and the organism as a whole. Plant anatomy is considered as part of botany, animal anatomy is considered as part of zoology, and human anatomy is a separate science. Physiology- biological science that studies the life processes of plant and animal organisms, their individual systems, organs, tissues and cells. There is physiology of plants, animals and humans. Embryology (developmental biology)- a branch of biology, the science of the individual development of an organism, including the development of the embryo.

Object genetics are the laws of heredity and variability. Currently, it is one of the most dynamically developing biological sciences.

According to the level of organization of living nature being studied, molecular biology, cytology, histology, organology, biology of organisms and superorganismal systems are distinguished. Molecular biology is one of the youngest branches of biology, a science that studies, in particular, the organization of hereditary information and protein biosynthesis. Cytology, or cell biology, is a biological science, the object of study of which is the cells of both unicellular and multicellular organisms. Histology- biological science, a branch of morphology, the object of which is the structure of tissues of plants and animals. The field of organology includes the morphology, anatomy and physiology of various organs and their systems.

Organismal biology includes all sciences that deal with living organisms, e.g. ethology- the science of behavior of organisms.

The biology of supraorganismal systems is divided into biogeography and ecology. Studies the distribution of living organisms biogeography, whereas ecology- organization and functioning of supraorganismal systems at various levels: populations, biocenoses (communities), biogeocenoses (ecosystems) and the biosphere.

According to the prevailing research methods, we can distinguish descriptive (for example, morphology), experimental (for example, physiology) and theoretical biology.

Identifying and explaining the patterns of structure, functioning and development of living nature at various levels of its organization is a task general biology. It includes biochemistry, molecular biology, cytology, embryology, genetics, ecology, evolutionary science and anthropology. Evolutionary doctrine studies the causes, driving forces, mechanisms and general patterns of evolution of living organisms. One of its sections is paleontology- a science whose subject is the fossil remains of living organisms. Anthropology- a section of general biology, the science of the origin and development of humans as a biological species, as well as the diversity of modern human populations and the patterns of their interaction.

Applied aspects of biology are included in the field of biotechnology, breeding and other rapidly developing sciences. Biotechnology is the biological science that studies the use of living organisms and biological processes in production. It is widely used in the food (baking, cheese-making, brewing, etc.) and pharmaceutical industries (production of antibiotics, vitamins), for water purification, etc. Selection- the science of methods for creating breeds of domestic animals, varieties of cultivated plants and strains of microorganisms with properties necessary for humans. Selection is also understood as the process of changing living organisms, carried out by humans for their needs.

The progress of biology is closely related to the successes of other natural and exact sciences, such as physics, chemistry, mathematics, computer science, etc. For example, microscopy, ultrasound (ultrasound), tomography and other methods of biology are based on physical laws, and the study of the structure of biological molecules and processes occurring in living systems would be impossible without the use of chemical and physical methods. The use of mathematical methods makes it possible, on the one hand, to identify the presence of a natural connection between objects or phenomena, to confirm the reliability of the results obtained, and on the other hand, to model a phenomenon or process. Recently, computer methods, such as modeling, have become increasingly important in biology. At the intersection of biology and other sciences, a number of new sciences arose, such as biophysics, biochemistry, bionics, etc.

Achievements of biology

The most important events in the field of biology, which influenced the entire course of its further development, are: the establishment of the molecular structure of DNA and its role in the transmission of information in living matter (F. Crick, J. Watson, M. Wilkins); deciphering the genetic code (R. Holley, H. G. Korana, M. Nirenberg); discovery of gene structure and genetic regulation of protein synthesis (A. M. Lvov, F. Jacob, J. L. Monod, etc.); formulation of cell theory (M. Schleiden, T. Schwann, R. Virchow, K. Baer); study of patterns of heredity and variability (G. Mendel, H. de Vries, T. Morgan, etc.); formulation of the principles of modern systematics (C. Linnaeus), evolutionary theory (C. Darwin) and the doctrine of the biosphere (V. I. Vernadsky).

“ mad cow disease" (prions).

Work on the Human Genome program, which was carried out simultaneously in several countries and was completed at the beginning of this century, led us to the understanding that humans have about 25–30 thousand genes, but information from most of our DNA is never read , since it contains a huge number of regions and genes encoding traits that have lost significance for humans (tail, body hair, etc.). In addition, a number of genes responsible for the development of hereditary diseases, as well as drug target genes, have been deciphered. However, the practical application of the results obtained during the implementation of this program is postponed until the genomes of a significant number of people have been deciphered, and then it will become clear what their differences are. These goals have been set for a number of leading laboratories around the world working on the implementation of the ENCODE program.

Biological research is the foundation of medicine, pharmacy, and is widely used in agriculture and forestry, the food industry and other branches of human activity.

It is well known that only the “green revolution” of the 1950s made it possible to at least partially solve the problem of providing the rapidly growing population of the Earth with food and livestock with feed through the introduction of new plant varieties and advanced technologies for their cultivation. Due to the fact that the genetically programmed properties of agricultural crops have already been almost exhausted, a further solution to the food problem is associated with the widespread introduction of genetically modified organisms into production.

The production of many food products, such as cheeses, yoghurts, sausages, baked goods, etc., is also impossible without the use of bacteria and fungi, which is the subject of biotechnology.

Knowledge of the nature of pathogens, the processes of many diseases, mechanisms of immunity, patterns of heredity and variability have made it possible to significantly reduce mortality and even completely eradicate a number of diseases, such as smallpox. With the help of the latest achievements of biological science, the problem of human reproduction is also being solved.

A significant part of modern medicines is produced on the basis of natural raw materials, as well as thanks to the successes of genetic engineering, such as, for example, insulin, so necessary for patients with diabetes, is mainly synthesized by bacteria to which the corresponding gene has been transferred.

Biological research is no less important for preserving the environment and the diversity of living organisms, the threat of extinction of which calls into question the existence of humanity.

The greatest significance among the achievements of biology is the fact that they even form the basis for the construction of neural networks and genetic code in computer technology, and are also widely used in architecture and other industries. Without a doubt, the 21st century is the century of biology.

Methods of knowledge of living nature

Like any other science, biology has its own arsenal of methods. In addition to the scientific method of cognition used in other fields, methods such as historical, comparative-descriptive, etc. are widely used in biology.

The scientific method of cognition includes observation, formulation of hypotheses, experiment, modeling, analysis of results and derivation of general patterns.

Observation- this is the purposeful perception of objects and phenomena using the senses or instruments, determined by the task of the activity. The main condition for scientific observation is its objectivity, that is, the ability to verify the data obtained through repeated observation or the use of other research methods, such as experiment. The facts obtained as a result of observation are called data. They can be like high quality(describing smell, taste, color, shape, etc.), and quantitative, and quantitative data is more accurate than qualitative data.

Based on observational data, it is formulated hypothesis- a presumptive judgment about the natural connection of phenomena. The hypothesis is tested in a series of experiments. An experiment is called a scientifically conducted experiment, observation of the phenomenon being studied under controlled conditions, allowing one to identify the characteristics of a given object or phenomenon. The highest form of experiment is modeling- study of any phenomena, processes or systems of objects by constructing and studying their models. Essentially, this is one of the main categories of the theory of knowledge: any method of scientific research, both theoretical and experimental, is based on the idea of ​​modeling.

The experimental and simulation results are subject to careful analysis. Analysis called a method of scientific research by decomposing an object into its component parts or mentally dismembering an object through logical abstraction. Analysis is inextricably linked with synthesis. Synthesis is a method of studying a subject in its integrity, in the unity and interconnection of its parts. As a result of analysis and synthesis, the most successful research hypothesis becomes working hypothesis, and if it can withstand attempts to refute it and still successfully predicts previously unexplained facts and relationships, then it can become a theory.

Under theory understand a form of scientific knowledge that gives a holistic idea of ​​the patterns and essential connections of reality. The general direction of scientific research is to achieve higher levels of predictability. If no facts can change a theory, and the deviations from it that occur are regular and predictable, then it can be elevated to the rank of law- necessary, essential, stable, repeating relationship between phenomena in nature.

As the body of knowledge increases and research methods improve, hypotheses and well-established theories can be challenged, modified, and even rejected, since scientific knowledge itself is dynamic in nature and constantly subject to critical reinterpretation.

Historical method reveals patterns of the appearance and development of organisms, the formation of their structure and function. In a number of cases, with the help of this method, hypotheses and theories that were previously considered false gain new life. This, for example, happened with Charles Darwin’s assumptions about the nature of signal transmission in a plant in response to environmental influences.

Comparative-descriptive method provides for anatomical and morphological analysis of research objects. It underlies the classification of organisms, identifying patterns of emergence and development of various forms of life.

Monitoring is a system of measures for observing, assessing and forecasting changes in the state of the object under study, in particular the biosphere.

Carrying out observations and experiments often requires the use of special equipment, such as microscopes, centrifuges, spectrophotometers, etc.

Microscopy is widely used in zoology, botany, human anatomy, histology, cytology, genetics, embryology, paleontology, ecology and other branches of biology. It allows you to study the fine structure of objects using light, electron, X-ray and other types of microscopes.

Light microscope device. A light microscope consists of optical and mechanical parts. The first includes the eyepiece, objectives and mirror, and the second includes the tube, tripod, base, stage and screw.

The total magnification of the microscope is determined by the formula:

lens magnification $×$ eyepiece magnification $-$ microscope magnification.

For example, if the lens magnifies an object by $8$ times and the eyepiece by $7$, then the total magnification of the microscope is $56$.

Differential centrifugation, or fractionation, allows you to separate particles according to their size and density under the influence of centrifugal force, which is actively used in studying the structure of biological molecules and cells.

The arsenal of biological methods is constantly updated, and at present it is almost impossible to fully cover it. Therefore, some methods used in individual biological sciences will be discussed below.

The role of biology in the formation of the modern natural science picture of the world

At the stage of its formation, biology did not yet exist separately from other natural sciences and was limited only to observation, study, description and classification of representatives of the animal and plant world, i.e. it was a descriptive science. However, this did not prevent the ancient naturalists Hippocrates (c. 460–377 BC), Aristotle (384–322 BC) and Theophrastus (real name Tirtham, 372–287 BC). BC) to make a significant contribution to the development of ideas about the structure of the human body and animals, as well as the biological diversity of animals and plants, thereby laying the foundations of human anatomy and physiology, zoology and botany.

The deepening of knowledge about living nature and the systematization of previously accumulated facts, which occurred in the 16th–18th centuries, culminated in the introduction of binary nomenclature and the creation of a harmonious taxonomy of plants (C. Linnaeus) and animals (J. B. Lamarck).

The description of a significant number of species with similar morphological characteristics, as well as paleontological finds, became prerequisites for the development of ideas about the origin of species and the paths of historical development of the organic world. Thus, the experiments of F. Redi, L. Spallanzani and L. Pasteur in the 17th–19th centuries refuted the hypothesis of spontaneous generation, put forward by Aristotle and prevalent in the Middle Ages, and the theory of biochemical evolution by A. I. Oparin and J. Haldane, brilliantly confirmed by S. Miller and G. Yuri, allowed us to answer the question about the origin of all living things.

If the process of the emergence of living things from non-living components and its evolution in themselves no longer raise doubts, then the mechanisms, paths and directions of the historical development of the organic world are still not fully understood, since neither of the two main competing theories of evolution (synthetic theory of evolution , created on the basis of the theory of C. Darwin, and the theory of J. B. Lamarck) still cannot provide comprehensive evidence.

The use of microscopy and other methods of related sciences, due to progress in the field of other natural sciences, as well as the introduction of experimental practice, allowed the German scientists T. Schwann and M. Schleiden to formulate a cell theory back in the 19th century, later supplemented by R. Virchow and K. Baer. It became the most important generalization in biology, which formed the cornerstone of modern ideas about the unity of the organic world.

The discovery of patterns of transmission of hereditary information by the Czech monk G. Mendel served as an impetus for the further rapid development of biology in the 20th–21st centuries and led not only to the discovery of the universal carrier of heredity - DNA, but also the genetic code, as well as the fundamental mechanisms of control, reading and variability of hereditary information .

The development of ideas about the environment led to the emergence of such a science as ecology, and the formulation teachings about the biosphere as a complex multi-component planetary system of interconnected huge biological complexes, as well as chemical and geological processes occurring on Earth (V.I. Vernadsky), which ultimately makes it possible to at least to a small extent reduce the negative consequences of human economic activity.

Thus, biology played an important role in the formation of the modern natural science picture of the world.

Level organization and evolution. The main levels of organization of living nature: cellular, organismal, population-species, biogeocenotic, biosphere. Biological systems. General characteristics of biological systems: cellular structure, features of chemical composition, metabolism and energy conversion, homeostasis, irritability, movement, growth and development, reproduction, evolution

Level organization and evolution

Living nature is not a homogeneous formation, like a crystal; it is represented by an infinite variety of its constituent objects (about 2 million species of organisms alone are currently described). At the same time, this diversity is not evidence of the chaos reigning in it, since organisms have a cellular structure, organisms of the same species form populations, all populations living on one piece of land or water form communities, and in interaction with bodies of inanimate nature they form biogeocenoses , in turn making up the biosphere.

Thus, living nature is a system, the components of which can be arranged in a strict order: from lower to higher. This principle of organization makes it possible to distinguish individual levels and gives a comprehensive understanding of life as a natural phenomenon. At each level of organization, an elementary unit and an elementary phenomenon are determined. As elementary unit consider a structure or object, changes in which constitute a contribution specific to the corresponding level to the process of preservation and development of life, while this change itself is an elementary phenomenon.

The formation of such a multi-level structure could not happen instantly - this is the result of billions of years of historical development, during which there was a progressive complication of life forms: from complexes of organic molecules to cells, from cells to organisms, etc. Once formed, this structure maintains its existence due to a complex regulatory system and continues to develop, and at each of the levels of organization of living matter, corresponding evolutionary transformations occur.

The main levels of organization of living nature: cellular, organismal, population-species, biogeocenotic, biosphere

Currently, there are several main levels of organization of living matter: cellular, organismal, population-species, biogeocenotic and biosphere.

Cellular level

Although the manifestations of some properties of living things are already due to the interaction of biological macromolecules (proteins, nucleic acids, polysaccharides, etc.), the unit of structure, functions and development of living things is the cell, which is capable of carrying out and coupling the processes of implementation and transmission of hereditary information with metabolism and energy conversion , thereby ensuring the functioning of higher levels of the organization. The elementary unit of the cellular level of organization is the cell, and the elementary phenomenon is the reactions of cellular metabolism.

Organismal level

Organism is an integral system capable of independent existence. Based on the number of cells that make up organisms, they are divided into unicellular and multicellular. The cellular level of organization in unicellular organisms (amoeba vulgaris, green euglena, etc.) coincides with the organismal level. There was a period in the history of the Earth when all organisms were represented only by single-celled forms, but they ensured the functioning of both biogeocenoses and the biosphere as a whole. Most multicellular organisms are represented by a collection of tissues and organs, which in turn also have a cellular structure. Organs and tissues are adapted to perform specific functions. The elementary unit of this level is the individual in its individual development, or ontogenesis, therefore the organismal level is also called ontogenetic. An elementary phenomenon at this level is changes in the body in its individual development.

Population-species level

Population- this is a collection of individuals of the same species, freely interbreeding with each other and living separately from other similar groups of individuals.

In populations there is a free exchange of hereditary information and its transmission to descendants. A population is an elementary unit of the population-species level, and the elementary phenomenon in this case is evolutionary transformations, such as mutations and natural selection.

Biogeocenotic level

Biogeocenosis is a historically established community of populations of different species, interconnected with each other and the environment by metabolism and energy.

Biogeocenoses are elementary systems in which the material and energy cycle occurs, determined by the vital activity of organisms. Biogeocenoses themselves are elementary units of a given level, while elementary phenomena are flows of energy and cycles of substances in them. Biogeocenoses make up the biosphere and determine all the processes occurring in it.

Biosphere level

Biosphere- the shell of the Earth inhabited by living organisms and transformed by them.

The biosphere is the highest level of organization of life on the planet. This shell covers the lower part of the atmosphere, the hydrosphere and the upper layer of the lithosphere. The biosphere, like all other biological systems, is dynamic and is actively transformed by living beings. It itself is an elementary unit of the biosphere level, and the processes of circulation of substances and energy that occur with the participation of living organisms are considered as an elementary phenomenon.

As mentioned above, each of the levels of organization of living matter makes its contribution to a single evolutionary process: in the cell, not only the embedded hereditary information is reproduced, but also its change occurs, which leads to the emergence of new combinations of characteristics and properties of the organism, which in turn are subject to the action of natural selection at the population-species level, etc.

Biological systems

Biological objects of varying degrees of complexity (cells, organisms, populations and species, biogeocenoses and the biosphere itself) are currently considered as biological systems.

A system is a unity of structural components, the interaction of which gives rise to new properties compared to their mechanical totality. Thus, organisms consist of organs, organs are formed by tissues, and tissues form cells.

The characteristic features of biological systems are their integrity, the level principle of organization, as discussed above, and openness. The integrity of biological systems is largely achieved through self-regulation, operating on the feedback principle.

TO open systems include systems between which the exchange of substances, energy and information occurs between them and the environment, for example, plants, in the process of photosynthesis, capture sunlight and absorb water and carbon dioxide, releasing oxygen.

General characteristics of biological systems: cellular structure, features of chemical composition, metabolism and energy conversion, homeostasis, irritability, movement, growth and development, reproduction, evolution

Biological systems differ from bodies of inanimate nature by a set of signs and properties, among which the main ones are cellular structure, chemical composition, metabolism and energy conversion, homeostasis, irritability, movement, growth and development, reproduction and evolution.

The elementary structural and functional unit of a living thing is the cell. Even viruses that belong to non-cellular life forms are incapable of self-reproduction outside cells.

There are two types of cell structure: prokaryotic And eukaryotic. Prokaryotic cells do not have a formed nucleus; their genetic information is concentrated in the cytoplasm. Prokaryotes primarily include bacteria. Genetic information in eukaryotic cells is stored in a special structure - the nucleus. Eukaryotes include plants, animals and fungi. If in unicellular organisms all manifestations of life are inherent in the cell, then in multicellular organisms cell specialization occurs.

There is not a single chemical element found in living organisms that does not exist in inanimate nature, but their concentrations differ significantly in the first and second cases. In living nature, elements such as carbon, hydrogen and oxygen predominate, which are part of organic compounds, while inanimate nature is mainly characterized by inorganic substances. The most important organic compounds are nucleic acids and proteins, which provide the functions of self-reproduction and self-maintenance, but none of these substances is a carrier of life, since neither individually nor in a group they are capable of self-reproduction - this requires an integral complex of molecules and structures, which is the cell.

All living systems, including cells and organisms, are open systems. However, unlike inanimate nature, where mainly the transfer of substances from one place to another or a change in their state of aggregation occurs, living beings are capable of chemical transformation of consumed substances and the use of energy. Metabolism and energy conversion are associated with processes such as nutrition, respiration and excretion.

Under food usually understand the entry into the body, digestion and assimilation of substances necessary for replenishing energy reserves and building the body of the body. According to the method of nutrition, all organisms are divided into autotrophs And heterotrophs.

Autotrophs- these are organisms that are capable of synthesizing organic substances from inorganic ones.

Heterotrophs- These are organisms that consume ready-made organic substances for food. Autotrophs are divided into photoautotrophs and chemoautotrophs. Photoautotrophs use the energy of sunlight to synthesize organic substances. The process of converting light energy into the energy of chemical bonds of organic compounds is called photosynthesis. The vast majority of plants and some bacteria (for example, cyanobacteria) are photoautotrophs. In general, photosynthesis is not a very productive process, as a result of which most plants are forced to lead an attached lifestyle. Chemoautotrophs extract energy for the synthesis of organic compounds from inorganic compounds. This process is called chemosynthesis. Typical chemoautotrophs are some bacteria, including sulfur bacteria and iron bacteria.

The remaining organisms - animals, fungi and the vast majority of bacteria - are heterotrophs.

Respiration is the process of breaking down organic substances into simpler ones, which releases the energy necessary to maintain the life of organisms.

Distinguish aerobic respiration, requiring oxygen, and anaerobic, occurring without the participation of oxygen. Most organisms are aerobes, although anaerobes are also found among bacteria, fungi and animals. With oxygen respiration, complex organic substances can be broken down into water and carbon dioxide.

Excretion usually refers to the removal from the body of metabolic end products and excess of various substances (water, salts, etc.) received from food or formed in it. Excretion processes are especially intense in animals, while plants are extremely economical.

Thanks to metabolism and energy, the body's relationship with the environment is ensured and homeostasis is maintained.

Homeostasis- this is the ability of biological systems to withstand changes and maintain relative constancy of chemical composition, structure and properties, as well as ensure constancy of functioning in changing environmental conditions. Adaptation to changing environmental conditions is called adaptation.

Irritability- this is the universal property of living things to respond to external and internal influences, which underlies the organism’s adaptation to environmental conditions and their survival. The reaction of plants to changes in external conditions consists, for example, in turning leaf blades towards the light, and in most animals it has more complex forms that are reflexive in nature.

Movement- an integral property of biological systems. It manifests itself not only in the form of movement of bodies and their parts in space, for example, in response to irritation, but also in the process of growth and development.

New organisms that appear as a result of reproduction do not receive ready-made characteristics from their parents, but certain genetic programs, the possibility of developing certain characteristics. This hereditary information is realized during individual development. Individual development is expressed, as a rule, in quantitative and qualitative changes in the body. Quantitative changes in the body are called growth. They manifest themselves, for example, in the form of an increase in the mass and linear dimensions of the organism, which is based on the reproduction of molecules, cells and other biological structures.

Development of the organism- this is the appearance of qualitative differences in structure, complication of functions, etc., which is based on cell differentiation.

The growth of organisms can continue throughout life or end at some specific stage. In the first case we talk about unlimited, or open growth. It is characteristic of plants and fungi. In the second case we are dealing with limited, or closed growth, characteristic of animals and bacteria.

The duration of existence of an individual cell, organism, species and other biological systems is limited in time, mainly due to the influence of environmental factors, so constant reproduction of these systems is required. The reproduction of cells and organisms is based on the process of self-duplication of DNA molecules. The reproduction of organisms ensures the existence of the species, and the reproduction of all species inhabiting the Earth ensures the existence of the biosphere.

Heredity call the transmission of characteristics of parental forms over a number of generations.

However, if the characteristics were preserved during reproduction, adaptation to changing environmental conditions would be impossible. In this regard, a property opposite to heredity appeared - variability.

Variability- this is the possibility of acquiring new characteristics and properties during life, which ensures the evolution and survival of the most adapted species.

Evolution is an irreversible process of historical development of living things.

It is based on progressive reproduction, hereditary variability, struggle for existence And natural selection. The action of these factors has led to a huge variety of life forms adapted to different environmental conditions. Progressive evolution has passed through a number of stages: precellular forms, unicellular organisms, increasingly complex multicellular organisms up to humans.

Genetics, its tasks. Heredity and variability are properties of organisms. Genetics methods. Basic genetic concepts and symbolism. Chromosomal theory of heredity. Modern ideas about the gene and genome

Genetics, its tasks

Advances in natural science and cell biology in the 18th–19th centuries allowed a number of scientists to make assumptions about the existence of certain hereditary factors that determine, for example, the development of hereditary diseases, but these assumptions were not supported by relevant evidence. Even the theory of intracellular pangenesis formulated by H. de Vries in 1889, which assumed the existence in the cell nucleus of certain “pangenes” that determine the hereditary inclinations of the organism, and the release into protoplasm of only those of them that determine the type of cell, could not change the situation, as well as the theory of “germ plasm” by A. Weissman, according to which characteristics acquired during the process of ontogenesis are not inherited.

Only the works of the Czech researcher G. Mendel (1822–1884) became the foundation stone of modern genetics. However, despite the fact that his works were cited in scientific publications, his contemporaries did not pay attention to them. And only the rediscovery of the patterns of independent inheritance by three scientists at once - E. Chermak, K. Correns and H. de Vries - forced the scientific community to turn to the origins of genetics.

Genetics is a science that studies the patterns of heredity and variability and methods of managing them.

The tasks of genetics at the present stage are the study of qualitative and quantitative characteristics of hereditary material, analysis of the structure and functioning of the genotype, deciphering the fine structure of the gene and methods for regulating gene activity, searching for genes that cause the development of hereditary human diseases and methods for “correcting” them, creating a new generation of drugs according to the type DNA vaccines, the construction, using genetic and cellular engineering, of organisms with new properties that could produce the medicines and food products needed by humans, as well as the complete deciphering of the human genome.

Heredity and variability - properties of organisms

Heredity is the ability of organisms to transmit their characteristics and properties over a series of generations.

Variability- the ability of organisms to acquire new characteristics during life.

Signs- these are any morphological, physiological, biochemical and other characteristics of organisms by which some of them differ from others, for example eye color. Properties also called any functional characteristics of organisms, which are based on a certain structural characteristic or group of elementary characteristics.

The characteristics of organisms can be divided into quality And quantitative. Qualitative signs have two or three contrasting manifestations, which are called alternative signs, for example, blue and brown eye colors, while quantitative ones (milk yield of cows, wheat yield) do not have clearly defined differences.

The material carrier of heredity is DNA. In eukaryotes, there are two types of heredity: genotypic And cytoplasmic. The carriers of genotypic heredity are localized in the nucleus and will be discussed further, while the carriers of cytoplasmic heredity are the circular DNA molecules located in mitochondria and plastids. Cytoplasmic heredity is transmitted mainly with the egg, therefore it is also called maternal.

A small number of genes are localized in the mitochondria of human cells, but their changes can have a significant impact on the development of the organism, for example, leading to the development of blindness or a gradual decrease in mobility. Plastids play an equally important role in plant life. Thus, in some areas of the leaf, chlorophyll-free cells may be present, which leads, on the one hand, to a decrease in plant productivity, and on the other hand, such variegated organisms are valued in decorative landscaping. Such specimens reproduce mainly asexually, since sexual reproduction often produces ordinary green plants.

Genetics methods

1. The hybridological method, or the method of crossings, consists of selecting parental individuals and analyzing the offspring. In this case, the genotype of an organism is judged by the phenotypic manifestations of genes in descendants obtained through a certain crossing scheme. This is the oldest informative method of genetics, which was most fully first used by G. Mendel in combination with the statistical method. This method is not applicable in human genetics for ethical reasons.

2. The cytogenetic method is based on the study of the karyotype: the number, shape and size of the organism’s chromosomes. The study of these features allows us to identify various developmental pathologies.

3. The biochemical method allows you to determine the content of various substances in the body, especially their excess or deficiency, as well as the activity of a number of enzymes.

4. Molecular genetic methods are aimed at identifying variations in the structure and deciphering the primary nucleotide sequence of the DNA sections under study. They make it possible to identify genes for hereditary diseases even in embryos, establish paternity, etc.

5. The population statistical method makes it possible to determine the genetic composition of a population, the frequency of certain genes and genotypes, genetic load, and also outline the prospects for the development of a population.

6. The method of hybridization of somatic cells in culture makes it possible to determine the localization of certain genes in chromosomes during the fusion of cells of different organisms, for example, a mouse and a hamster, a mouse and a human, etc.

Basic genetic concepts and symbolism

Gene- this is a section of a DNA molecule, or chromosome, that carries information about a certain trait or property of an organism.

Some genes can influence the manifestation of several traits at once. This phenomenon is called pleiotropy. For example, the gene that causes the development of the hereditary disease arachnodactyly (spider fingers) also causes curvature of the lens and pathologies of many internal organs.

Each gene occupies a strictly defined place on the chromosome - locus. Since in the somatic cells of most eukaryotic organisms the chromosomes are paired (homologous), each of the paired chromosomes contains one copy of the gene responsible for a certain trait. Such genes are called allelic.

Allelic genes most often exist in two versions - dominant and recessive. Dominant called an allele that manifests itself regardless of which gene is located on the other chromosome and suppresses the development of the trait encoded by the recessive gene. Dominant alleles are usually designated in capital letters of the Latin alphabet (A, B, C, etc.), and recessive alleles are designated in lowercase letters (a, b, c, etc.). Recessive alleles can only be expressed if they occupy loci on both paired chromosomes.

An organism that has the same alleles on both homologous chromosomes is called homozygous for this gene, or homozygous(AA, aa, AABB, aabb, etc.), and an organism that has different gene variants on both homologous chromosomes - dominant and recessive - is called heterozygous for this gene, or heterozygous(Aa, AaBb, etc.).

A number of genes may have three or more structural variants, for example, blood groups according to the AB0 system are encoded by three alleles - I A, I B, i. This phenomenon is called multiple allelism. However, even in this case, each chromosome of a pair carries only one allele, that is, all three gene variants cannot be represented in one organism.

Genome- a set of genes characteristic of a haploid set of chromosomes.

Genotype- a set of genes characteristic of a diploid set of chromosomes.

Phenotype- a set of characteristics and properties of an organism, which is the result of the interaction of the genotype and the environment.

Since organisms differ from each other in many traits, the patterns of their inheritance can only be established by analyzing two or more traits in the offspring. Crossing, in which inheritance is considered and an accurate quantitative count of the offspring is carried out according to one pair of alternative characteristics, is called monohybrid m, in two pairs - dihybrid, according to a larger number of signs - polyhybrid.

Based on the phenotype of an individual, it is not always possible to determine its genotype, since both an organism homozygous for the dominant gene (AA) and heterozygous (Aa) will have a manifestation of the dominant allele in the phenotype. Therefore, to check the genotype of an organism with cross-fertilization, they use test cross- crossbreeding, in which an organism with a dominant trait is crossed with one homozygous for a recessive gene. In this case, an organism homozygous for the dominant gene will not produce splitting in the offspring, whereas in the offspring of heterozygous individuals there is an equal number of individuals with dominant and recessive traits.

The following conventions are most often used to record crossing schemes:

R (from lat. parenta- parents) - parent organisms;

$♀$ (alchemical sign of Venus - mirror with handle) - maternal specimen;

$♂$ (alchemical sign of Mars - shield and spear) - paternal individual;

$×$ - crossing sign;

F 1, F 2, F 3, etc. - hybrids of the first, second, third and subsequent generations;

F a - offspring from an analyzing cross.

Chromosomal theory of heredity

The founder of genetics, G. Mendel, as well as his closest followers, did not have the slightest idea about the material basis of hereditary inclinations, or genes. However, already in 1902–1903, the German biologist T. Boveri and the American student W. Satton independently suggested that the behavior of chromosomes during cell maturation and fertilization makes it possible to explain the splitting of hereditary factors according to Mendel, i.e., in their opinion, genes must be located on chromosomes. These assumptions became the cornerstone of the chromosomal theory of heredity.

In 1906, English geneticists W. Bateson and R. Punnett discovered a violation of Mendelian segregation when crossing sweet peas, and their compatriot L. Doncaster, in experiments with the gooseberry moth butterfly, discovered sex-linked inheritance. The results of these experiments clearly contradicted Mendelian ones, but if we consider that by that time it was already known that the number of known characteristics for experimental objects far exceeded the number of chromosomes, and this suggested that each chromosome carries more than one gene, and the genes of one chromosomes are inherited together.

In 1910, experiments by T. Morgan's group began on a new experimental object - the Drosophila fruit fly. The results of these experiments made it possible by the mid-20s of the 20th century to formulate the basic principles of the chromosomal theory of heredity, to determine the order of genes in chromosomes and the distances between them, i.e., to draw up the first maps of chromosomes.

Basic provisions of the chromosomal theory of heredity:

1. Genes are located on chromosomes. Genes on the same chromosome are inherited together, or linked, and are called clutch group. The number of linkage groups is numerically equal to the haploid set of chromosomes.
2. Each gene occupies a strictly defined place on the chromosome - a locus.
3. Genes are arranged linearly on chromosomes.
4. Disruption of gene linkage occurs only as a result of crossing over.
5. The distance between genes on a chromosome is proportional to the percentage of crossing over between them.
6. Independent inheritance is typical only for genes on non-homologous chromosomes.

Modern ideas about the gene and genome

In the early 40s of the twentieth century, J. Beadle and E. Tatum, analyzing the results of genetic studies conducted on the neurospora fungus, came to the conclusion that each gene controls the synthesis of an enzyme, and formulated the principle of “one gene - one enzyme” .

However, already in 1961, F. Jacob, J. L. Monod and A. Lvov managed to decipher the structure of the E. coli gene and study the regulation of its activity. For this discovery they were awarded the Nobel Prize in Physiology or Medicine in 1965.

In the process of research, in addition to structural genes that control the development of certain traits, they were able to identify regulatory ones, the main function of which is the manifestation of traits encoded by other genes.

Structure of a prokaryotic gene. The structural gene of prokaryotes has a complex structure, since it includes regulatory regions and coding sequences. The regulatory regions include the promoter, operator, and terminator. Promoter called the region of the gene to which the enzyme RNA polymerase is attached, which ensures the synthesis of mRNA during transcription. WITH operator, located between the promoter and the structural sequence, can bind repressor protein, which does not allow RNA polymerase to begin reading the hereditary information from the coding sequence, and only its removal allows transcription to begin. The structure of the repressor is usually encoded in a regulatory gene located in another part of the chromosome. Reading of information ends at a section of the gene called terminator.

Coding sequence A structural gene contains information about the amino acid sequence of the corresponding protein. The coding sequence in prokaryotes is called cistronome, and the totality of coding and regulatory regions of a prokaryotic gene - operon. In general, prokaryotes, which include E. coli, have a relatively small number of genes located on a single circular chromosome.

The cytoplasm of prokaryotes may also contain additional small circular or open DNA molecules called plasmids. Plasmids are able to integrate into chromosomes and be transmitted from one cell to another. They may carry information about sex characteristics, pathogenicity and antibiotic resistance.

Structure of a eukaryotic gene. Unlike prokaryotes, eukaryotic genes do not have an operon structure, since they do not contain an operator, and each structural gene is accompanied only by a promoter and terminator. In addition, in eukaryotic genes significant regions ( exons) alternate with insignificant ones ( introns), which are completely transcribed into mRNA and then excised during their maturation. The biological role of introns is to reduce the likelihood of mutations in significant regions. The regulation of genes in eukaryotes is much more complex than that described for prokaryotes.

Human genome. In each human cell, the 46 chromosomes contain about 2 m of DNA, tightly packed into a double helix, which consists of approximately 3.2 $×$ 10 9 nucleotide pairs, which provides about 10 1900000000 possible unique combinations. By the end of the 80s of the twentieth century, the location of approximately 1,500 human genes was known, but their total number was estimated at approximately 100 thousand, since humans have approximately 10 thousand hereditary diseases alone, not to mention the number of various proteins contained in cells .

In 1988, the international Human Genome project was launched, which by the beginning of the 21st century ended with a complete decoding of the nucleotide sequence. He made it possible to understand that two different people have 99.9% similar nucleotide sequences, and only the remaining 0.1% determine our individuality. In total, approximately 30–40 thousand structural genes were discovered, but then their number was reduced to 25–30 thousand. Among these genes there are not only unique ones, but also repeated hundreds and thousands of times. However, these genes encode a much larger number of proteins, for example tens of thousands of protective proteins - immunoglobulins.

97% of our genome is genetic “junk” that exists only because it can reproduce well (RNA that is transcribed in these regions never leaves the nucleus). For example, among our genes there are not only “human” genes, but also 60% of genes similar to the genes of the Drosophila fly, and up to 99% of our genes are similar to chimpanzees.

In parallel with the decoding of the genome, chromosome mapping also took place, as a result of which it was possible not only to discover, but also to determine the location of some genes responsible for the development of hereditary diseases, as well as drug target genes.

Decoding the human genome has not yet given a direct effect, since we have received a kind of instruction for assembling such a complex organism as a person, but have not learned how to manufacture it or at least correct errors in it. Nevertheless, the era of molecular medicine is already on the threshold; all over the world, so-called gene preparations are being developed that can block, delete or even replace pathological genes in living people, and not just in a fertilized egg.

We should not forget that in eukaryotic cells DNA is contained not only in the nucleus, but also in mitochondria and plastids. Unlike the nuclear genome, the organization of genes in mitochondria and plastids has much in common with the organization of the prokaryotic genome. Despite the fact that these organelles carry less than 1% of the cell's hereditary information and do not even encode the full set of proteins necessary for their own functioning, they are capable of significantly influencing some of the body's characteristics. Thus, variegation in plants of chlorophytum, ivy and others is inherited by a small number of descendants even when crossing two variegated plants. This is due to the fact that plastids and mitochondria are transmitted mostly with the cytoplasm of the egg, therefore such heredity is called maternal, or cytoplasmic, in contrast to genotypic, which is localized in the nucleus.

Term "biology" is formed from two Greek words “bios” - life and “logos” - knowledge, teaching, science. Hence the classic definition of biology as a science that studies life in all its manifestations.

Biology explores the diversity of existing and extinct living beings, their structure, functions, origin, evolution, distribution and individual development, connections with each other, between communities and with inanimate nature.

Biology examines general and particular patterns inherent in life in all its manifestations and properties: metabolism, reproduction, heredity, variability, adaptability, growth, development, irritability, mobility, etc.

Research methods in biology

1. Observation- the simplest and most accessible method. For example, you can observe seasonal changes in nature, in the life of plants and animals, animal behavior, etc.
2. Description biological objects (oral or written description).
3. Comparison– finding similarities and differences between organisms, used in taxonomy.
4. Experimental method(in laboratory or natural conditions) – biological research using various instruments and methods of physics and chemistry.
5. Microscopy– study of the structure of cells and cellular structures using light and electron microscopes. Light microscopes allow you to see the shapes and sizes of cells and individual organelles. Electronic – small structures of individual organelles.
6. Biochemical method- study of the chemical composition of cells and tissues of living organisms.
7. Cytogenetic– a method of studying chromosomes under a microscope. You can detect genomic mutations (for example, Down syndrome), chromosomal mutations (changes in the shape and size of chromosomes).
8. Ultracentrifugation- isolation of individual cellular structures (organelles) and their further study.
9. Historical method– comparison of the obtained facts with previously obtained results.
10. Modeling– creation of various models of processes, structures, ecosystems, etc. in order to predict changes.
11. Hybridological method– the method of crossing, the main method of studying the patterns of heredity.
12. Genealogical method– a method of compiling pedigrees, used to determine the type of inheritance of a trait.
13. Twin method– a method that allows you to determine the share of influence of environmental factors on the development of traits. Applies to identical twins.

Connection of biology with other sciences.

The diversity of living nature is so great that modern biology must be presented as a complex of sciences. Biology underlies such sciences as medicine, ecology, genetics, selection, botany, zoology, anatomy, physiology, microbiology, embryology etc. Biology, together with other sciences, formed such sciences as biophysics, biochemistry, bionics, geobotany, zoogeography, etc. In connection with the rapid development of science and technology, new directions in the study of living organisms are emerging, and new sciences related to biology are appearing. This once again proves that the living world is multifaceted and complex and it is closely connected with inanimate nature.

Basic biological sciences - objects of their study

1. Anatomy is the external and internal structure of organisms.
2. Physiology – life processes.
3. Medicine - human diseases, their causes and methods of treatment.
4. Ecology – relationships between organisms in nature, patterns of processes in ecosystems.
5. Genetics - the laws of heredity and variability.
6. Cytology is the science of cells (structure, vital activity, etc.).
7. Biochemistry – biochemical processes in living organisms.
8. Biophysics – physical phenomena in living organisms.
9. Breeding is the creation of new and improvement of existing varieties, breeds, strains.
10. Paleontology – fossil remains of ancient organisms.
11. Embryology - development of embryos.

A person can apply knowledge in the field of biology:

• for the prevention and treatment of diseases
• when providing first aid victims of accidents;
• in crop production, livestock farming
• in environmental activities that contribute to solving global environmental problems (knowledge about the interrelations of organisms in nature, about factors that negatively affect the state of the environment, etc.). BIOLOGY AS A SCIENCE

Signs and properties of living things:

1. Cellular structure. The cell is a single structural and functional unit, as well as a unit of development for almost all living organisms on Earth. Viruses are an exception, but even they exhibit living properties only when they are in a cell. Outside the cell they do not show any signs of life.

2. Unity of chemical composition. Living things are made up of the same chemical elements as non-living things, but in living things 90% of the mass comes from four elements: S, O, N, N, which are involved in the formation of complex organic molecules, such as proteins, nucleic acids, carbohydrates, lipids.

3. Metabolism and energy are the main properties of living things. It is carried out as a result of two interrelated processes: the synthesis of organic substances in the body (due to external sources of energy from light and food) and the process of decomposition of complex organic substances with the release of energy, which is then consumed by the body. Metabolism ensures the constancy of the chemical composition in continuously changing environmental conditions.

4. Openness. All living organisms are open systems, i.e. systems that are stable only under the condition of a continuous supply of energy and matter from the environment.

5. Self-reproduction (reproduction). The ability to self-reproduce is the most important property of all living organisms. It is based on information about the structure and functions of any living organism, embedded in nucleic acids and ensuring the specificity of the structure and vital activity of a living organism.

6. Self-regulation. Thanks to the mechanisms of self-regulation, the relative constancy of the internal environment of the body is maintained, i.e. the constancy of the chemical composition and the intensity of the physiological processes are maintained - homeostasis.

7. Development and growth. In the process of individual development (ontogenesis), the individual properties of the organism gradually and consistently appear (development) and its growth occurs (increase in size). In addition, all living systems evolve - change during historical development (phylogeny).

8. Irritability. Any living organism is capable of responding to external and internal influences.

9. Heredity. All living organisms are capable of preserving and transmitting basic characteristics to offspring.

10. Variability. All living organisms are capable of changing and acquiring new characteristics.

Basic levels of organization of living nature

All living nature is a collection of biological systems. Important properties of living systems are multilevel and hierarchical organization. The parts of biological systems are themselves systems made up of interconnected parts. At every level, every biological system is unique and different from other systems.

Scientists, based on the characteristics of the manifestation of the properties of living things, have identified several levels of organization of living nature:

1. Molecular level - represented by molecules of organic substances (proteins, lipids, carbohydrates, etc.) found in cells. At the molecular level, one can study the properties and structures of biological molecules, their role in the cell, in the life of the organism, and so on. For example, doubling the DNA molecule, protein structure, and so on.

2. Cellular level – represented by cells. At the cellular level, the properties and signs of living things begin to appear. At the cellular level, one can study the structure and functions of cells and cellular structures, the processes occurring in them. For example, the movement of cytoplasm, cell division, protein biosynthesis in ribosomes, and so on.

3. Organ-tissue level – represented by tissues and organs of multicellular organisms. At this level, one can study the structure and functions of tissues and organs, the processes occurring in them. For example, contraction of the heart, movement of water and salts through vessels, and so on.

4. Organismal level – represented by unicellular and multicellular organisms. At this level, the organism is studied as a whole: its structure and vital functions, mechanisms of self-regulation of processes, adaptation to living conditions, and so on.

5. Population-species level– represented by populations consisting of individuals of the same species living together for a long time in a certain territory. The life of one individual is genetically determined, and under favorable conditions the population can exist indefinitely. Since at this level the driving forces of evolution begin to operate - the struggle for existence, natural selection, etc. At the population-species level, they study the dynamics of the number of individuals, the age-sex composition of the population, evolutionary changes in the population, and so on.

6. Ecosystem level– represented by populations of different species living together in a certain territory. At this level, the relationships between organisms and the environment, the conditions that determine the productivity and sustainability of ecosystems, changes in ecosystems, and so on are studied.

7. Biosphere level– the highest form of organization of living matter, uniting all ecosystems of the planet. At this level, processes are studied on the scale of the entire planet - cycles of matter and energy in nature, global environmental problems, changes in the Earth's climate, etc. Currently, the study of human influence on the state of the biosphere in order to prevent a global environmental crisis is of paramount importance.

Ticket 1 1.Biology as a science, its achievements, connections with other sciences. Methods for studying living objects. The role of biology in human life and practical activities. 2. The plant kingdom, its differences from other kingdoms of living nature. Explain which group of plants currently occupies a dominant position on Earth. Find representatives of this group among living plants or herbarium specimens. 3.Using knowledge about metabolism and energy conversion in the human body, give a scientific explanation of the effect of physical inactivity, stress, bad habits, and overeating on metabolism.

1. Biology (from Greek bios life, logos science) the science of life. She studies living organisms, their structure, development and origin, relationships with their environment and with other living organisms. 2. Biology - a set of sciences about life, about living nature (see table “System of biological sciences”). I. Biology as a science, its achievements in connection with other sciences. Methods for studying living objects. The role of biology in human life and practical activities.

3. Basic methods in biology 1.observation (allows you to describe biological phenomena), 2.comparison (makes it possible to find general patterns in the structure and life of various organisms), 3.experiment or experience (helps the researcher study the properties of biological objects), 4.modeling (processes that are inaccessible to observation or experimental reproduction are simulated), 5. historical method (based on data about the modern organic world and its past, the processes of development of living nature are learned).

4. Achievements of biology: 1). Description of the large number of species of living organisms existing on Earth; 2). Creation of cellular, evolutionary, chromosome theory; 3). The discovery of the molecular structure of the structural units of heredity (genes) served as the basis for the creation of genetic engineering. 4). The practical application of the achievements of modern biology makes it possible to obtain industrially significant amounts of biologically active substances.

6). Thanks to knowledge of the laws of heredity and variability, great successes have been achieved in agriculture in the creation of new highly productive breeds of domestic animals and varieties of cultivated plants. 5). Based on the study of relationships between organisms, biological methods for controlling crop pests have been created.

7).Great importance in biology is attached to elucidating the mechanisms of protein biosynthesis and the secrets of photosynthesis, which will open the way to obtaining organic nutrients. In addition, the use in industry (in construction, when creating new machines and mechanisms) of the principles of organization of living beings (bionics) brings at present and will give in the future a significant economic effect. The honeycomb design formed the basis for the production of "honeycomb panels" for construction

In such a situation, the only basis for increasing food resources can be the intensification of agriculture. An important role in this process will be played by the development of new highly productive forms of microorganisms, plants and animals, and the rational, scientifically based use of natural resources.

1. Plants are autotrophs and are capable of photosynthesis; 2. The presence of plastids with pigments in the cells; 3. The cells are surrounded by a cellulose wall; 4.Presence of vacuoles with cell sap in the cells; 5.Unlimited growth; 6. There are plant hormones - phytohormones; 7. Osmotic type of nutrition (receipt of nutrients in the form of aqueous solutions entering through the cell membrane).

Angiosperms or flowering plants are the largest division of modern higher plants, numbering about 250 thousand species. They grow in all climatic zones and are part of all biogeocenoses of the globe. This indicates their high adaptability to modern conditions of existence on Earth.

Adaptations in angiosperms (flowering plants) that allowed them to occupy a dominant position on Earth: I. The vegetative organs of flowering plants achieve the greatest complexity and diversity. II. Flowering plants have a more advanced conductive system, which provides better water supply to the plant. III. For the first time, flowering plants have a new organ - the flower. The ovules are enclosed in a closed cavity of the ovary, formed by one or more fused carpels. The seeds are enclosed in the fruit. Double fertilization appeared, which sharply distinguishes them from all other groups of the plant world. IV. The most important transformations took place in the conductive system. Instead of tracheids, vessels become the main conducting elements of the xylem, which significantly accelerates the movement of the ascending current. Thus, angiosperms received additional opportunities in the competition and ultimately became “winners” in the struggle for existence.

III. Using knowledge about metabolism and energy conversion in the human body, give a scientific explanation of the effect of physical inactivity, stress, bad habits, and overeating on metabolism. The body receives many substances from the outside, processes them, obtaining energy or those molecules that the body needs to build its own tissues. The resulting metabolic products are excreted from the body. The totality of all reactions of dissimilation (the breakdown of substances with the release of energy) and assimilation (the synthesis of substances necessary for the body) is called metabolism. In a healthy body, assimilation and dissimilation are strictly balanced. All metabolic reactions are regulated by the nervous and endocrine systems. Metabolic disorders underlie many human diseases.

1. Physical inactivity - reduced physical activity, lack of physical activity - leads to a decrease in the performance of muscles, the cardiovascular system and, as a consequence, metabolic disorders and a deterioration in the condition of the whole organism as a whole. Nutrients not spent on physical activity are stored, which often leads to obesity. Overeating also contributes to this (2).

3. Stress is a protective reaction of the body that allows it to survive in times of danger. Stress mobilizes the body's capabilities, is accompanied by the release of hormones, increases the intensity of cardiovascular activity, etc. However, severe and especially prolonged stress can lead to depletion of human strength and metabolic disorders.

4. Constant consumption of alcoholic beverages has a very strong negative effect on metabolism. In alcoholics, oxidizing ethyl alcohol gives the body a certain amount of energy, but it also produces very toxic substances that kill liver and brain cells. Gradually, the appetite of alcoholics decreases, and they stop eating normal amounts of proteins, fats and carbohydrates, replacing them with alcoholic beverages, which leads to destruction of the body. Chronic alcoholics always have damaged liver, they lose weight, and gradual muscle destruction occurs.

5. Smoking also has a strong negative effect on metabolism, since it destroys the lungs and prevents the body from receiving the required amount of oxygen. In addition, smoking greatly increases the likelihood of developing lung cancer.

6. Narcotic substances, participating in metabolism, cause addiction; subsequently, the cessation of the intake of nicotine, alcohol, etc. is accompanied by withdrawal symptoms - a sharp deterioration in well-being. Thus, physiological and psychological dependence on drugs occurs.