"Biosphere and Civilization" - Abiotic factors. Basic concepts of ecology. Environmental factor. Herbivores. American scientist. The book by V.I. Vernadsky "Biosphere". Human activities. The greenhouse effect. Ecological niche. Limiting factors. The lower boundary of the biosphere. Excess water. Edward Suess. Autotrophs. Anthropogenic factor. Consumption of water. Population growth. The position of the view in space. Compensating properties.
"The concept of the biosphere" - Human reactions to changes in the biosphere. Malaria. Evolution of the biosphere. Living matter in the biosphere. Films of life in the ocean. Portrait of Jean-Baptiste Lamarck. Sargassum algae. How philosophers represent the noosphere. Decomposition of organics and inorganics. An example of unsuccessful human intervention. Noosphere. Alive organisms. Special chemical composition. The nitrogen cycle. Composition of the biosphere. Riftia. Anaerobic bacteria.
"Biosphere as a global ecosystem" - Biosphere as a global biosystem and ecosystem. Inanimate nature. Living environments of organisms on Earth. Man as an inhabitant of the biosphere. Shell of the Earth. Biological circulation. Environmental factors. Alive organisms. Person. The biosphere as a global biosystem. Features of the biosphere level of living matter.
"Biosphere is a living shell of the Earth" - Inanimate nature. The appearance of the ancient inhabitants of our planet. Alive organisms. Rocks. Vegetation cover. Heat. Biosphere. Land. Green plants. Creatures.
"Composition and structure of the biosphere" - The boundaries of the biosphere. Evolutionary state. Vernadsky. Limiting factor. Hydrosphere. Earthly shell. Living substance. Lithosphere. Ozone layer. Noosphere. The structure of the biosphere. Biosphere. Atmosphere.
"Study of the Biosphere" - Bacteria, spores and pollen of plants. Interaction. The origin of life on Earth. What is the approximate age of the planet Earth? Viability. All organisms are united into 4 kingdoms of living nature. Variety of organisms. 40 thousand. years ago modern man appeared. How many types of mushrooms exist. The boundaries of the biosphere. Test yourself. What supplies the biosphere to the hydrosphere. Game "Biosphere". The variety of organisms on Earth.
MBOU Yasnogorskaya secondary school
Biology
10 A class
Textbook
Topic:
Target:
Tasks:
Equipment:
During the classes:
Slide 1
1.
Discussion on issues (slide number 2)
1. What is the noosphere?
2. Learning new material
Lesson plan:
3. Structural elements.
4. Basic processes.
5. Features of the organization.
3. Anchoring
The teacher sums up:
Questions
D / z. par.13. questions.
Prepare messages:
4.the living environment of organisms
5 environmental factors
6. Abiotic factors
7. Biotic factors
8. Anthropogenic factors
MBOU Yasnogorskaya secondary school
Beketova Nurziya Falyakhetdinovna
Biology
10 A class
Basic level program for general education institutions
Textbook Ponomareva I.N., Kornilova O.A., Loshchilina T.E., Izhevsky P.V. General biology
Topic: Features of the biospheric level of organization of living matter and its role in ensuring life on Earth.
Target: to summarize information about the global ecosystem of the Earth - the biosphere, the features of the biosphere level of organization of living matter and its role in ensuring life on Earth;
Tasks:
1. Check the ability to apply the knowledge gained about the biosphere level of the organization to substantiate situations, express and scientifically substantiate their point of view;
2. Continue the development of general educational skills (highlight the main thing, establish cause-and-effect relationships, work with schemes, establish the correctness of the statements made and the sequence of objects and phenomena);
3. To form a cognitive interest in the subject, develop communication and the ability to do work in groups;
4. Objectively assess the level of knowledge and skills of schoolchildren according to the studied section "Biosphere level of life organization"
Equipment: table "Biosphere and its boundaries", presentation.
During the classes:
Slide 1
1. Generalization and systematization of knowledge
Discussion on issues (slide number 2)
1. What is the noosphere?
2. Who is the founder of the noosphere?
3. From what moment (in your opinion) did a person begin to influence (negatively) the biosphere?
4. What happens if the upper limit of the biosphere's capacity is exceeded?
5. Give examples of the impact of society on nature, which goes through the channels of positive feedback. What do you think of it?
2. Learning new material
Lesson plan:
1. Features of the biosphere level.
2. Characteristics of the biosphere level.
3. Structural elements.
4. Basic processes.
5. Features of the organization.
6. The meaning of the biosphere level.
3. Anchoring
The teacher sums up:
The biospheric standard of living is characterized by special qualities, the degree of complexity and patterns of organization; it includes living organisms and the natural communities they form, geographic envelopes and anthropogenic activities. At the biosphere level, very important global processes take place that provide the possibility of the existence of life on Earth: the formation of oxygen, the absorption and transformation of solar energy, the maintenance of a constant gas composition, the implementation of biochemical cycles and energy flow, the development of biological diversity of species and ecosystems. The variety of life forms on Earth ensures the stability of the biosphere, its integrity and unity. The main strategy of life at the biosphere level is to preserve the diversity of forms of living matter and the infinity of life, to ensure the dynamic stability of the biosphere.
4. Summing up and control of knowledge
Schoolchildren are invited to test their knowledge and skills in this section.
Questions
1. You know that the biospheric level of organization of living things is the highest and most complex. List the lower levels of life organization included in the biosphere level, in the order of their complexity.
2. Name the signs that allow to characterize the biosphere as a structural level of life organization.
3. What are the main components that form the structure of the biosphere?
4. Name the main processes inherent in the biosphere.
5. Why is the economic and ethnocultural activity of man related to the main processes in the biosphere?
6. What phenomena organize the stability of the biosphere, that is, control the processes in it?
7. Knowledge of what, in addition to the structure, processes and organization, is necessary for a complete understanding of the structure of the biosphere?
8. Formulate a general conclusion about the importance of the biospheric level of organization of life on Earth.
D / z. par.13. questions.
Prepare messages:
1. man as a factor in the biosphere.
2.Scientific basis for the conservation of the biosphere
3. Objectives of sustainable development
4.the living environment of organisms
5 environmental factors
6. Abiotic factors
7. Biotic factors
8. Anthropogenic factors
Basic level program for general education institutions
Textbook Ponomareva I.N., Kornilova O.A., Loshchilina T.E., Izhevsky P.V. General biology
Topic: Features of the biospheric level of organization of living matter and its role in ensuring life on Earth.
Target: to summarize information about the global ecosystem of the Earth - the biosphere, the features of the biosphere level of organization of living matter and its role in ensuring life on Earth;
Tasks:
1. Check the ability to apply the knowledge gained about the biosphere level of the organization to substantiate situations, express and scientifically substantiate their point of view;
2. Continue the development of general educational skills (highlight the main thing, establish cause-and-effect relationships, work with schemes, establish the correctness of the statements made and the sequence of objects and phenomena);
3. To form a cognitive interest in the subject, develop communication and the ability to do work in groups;
4. Objectively assess the level of knowledge and skills of schoolchildren according to the studied section "Biosphere level of life organization"
Equipment: table "Biosphere and its boundaries", presentation.
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Objectively assess the level of knowledge and skills of schoolchildren according to the studied section "Biosphere level of life organization"
Equipment: table "Biosphere and its boundaries", presentation.
During the classes:
Slide 1
1. Generalization and systematization of knowledge
Discussion on issues (slide number 2)
1. What is the noosphere?
2. Who is the founder of the noosphere?
3. From what moment (in your opinion) did a person begin to influence (negatively) the biosphere?
4. What happens if the upper limit of the biosphere's capacity is exceeded?
5. Give examples of the impact of society on nature, which goes through the channels of positive feedback. What do you think of it?
2. Learning new material
Lesson plan:
1. Features of the biosphere level.
2. Characteristics of the biosphere level.
3. Structural elements.
4. Basic processes.
5. Features of the organization.
6. The meaning of the biosphere level.
3. Anchoring
The teacher sums up:
The biospheric standard of living is characterized by special qualities, the degree of complexity and patterns of organization; it includes living organisms and the natural communities they form, geographic envelopes and anthropogenic activities. At the biosphere level, very important global processes take place that provide the possibility of the existence of life on Earth: the formation of oxygen, the absorption and transformation of solar energy, the maintenance of a constant gas composition, the implementation of biochemical cycles and energy flow, the development of biological diversity of species and ecosystems. The variety of life forms on Earth ensures the stability of the biosphere, its integrity and unity. The main strategy of life at the biosphere level is to preserve the diversity of forms of living matter and the infinity of life, to ensure the dynamic stability of the biosphere.
4. Summing up and control of knowledge
Schoolchildren are invited to test their knowledge and skills in this section.
Questions
1. You know that the biospheric level of organization of living things is the highest and most complex. List the lower levels of life organization included in the biosphere level, in the order of their complexity.
2. Name the signs that allow to characterize the biosphere as a structural level of life organization.
3. What are the main components that form the structure of the biosphere?
4. Name the main processes inherent in the biosphere.
5. Why is the economic and ethnocultural activity of man related to the main processes in the biosphere?
6. What phenomena organize the stability of the biosphere, that is, control the processes in it?
7. Knowledge of what, in addition to the structure, processes and organization, is necessary for a complete understanding of the structure of the biosphere?
8. Formulate a general conclusion about the importance of the biospheric level of organization of life on Earth.
D / z. par.13. questions.
Prepare messages:
1. man as a factor in the biosphere.
2.Scientific basis for the conservation of the biosphere
3. Objectives of sustainable development
4.the living environment of organisms
5 environmental factors
6. Abiotic factors
7. Biotic factors
8. Anthropogenic factors
Naturalistic biology Aristotle: - Divided the animal kingdom into two groups: those with blood and those without blood. - Man at the top of blood animals (anthropocentrism). K. Linnaeus: -developed a harmonious hierarchy of all animals and plants (species - genus - detachment - class), -introduced precise terminology for describing plants and animals.
Evolutionary biology The question of the origin and essence of life. J. B. Lamarck proposed the first evolutionary theory in 1809 by J. Cuvier - the theory of catastrophes. C. Darwin evolutionary theory in 1859 evolutionary theory in 1859 Modern (synthetic) theory of evolution (represents the synthesis of genetics and Darwinism).
Molecular genetic level The level of functioning of biopolymers (proteins, nucleic acids, polysaccharides), etc., underlying the vital processes of organisms. Elementary structural unit - gene The carrier of hereditary information is a DNA molecule.
Nucleic acids Complex organic compounds that are phosphorus-containing biopolymers (polynucleotides). Types: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The body's genetic information is stored in DNA molecules. They have the property of molecular dissymmetry (asymmetry), or molecular chirality - they are optically active.
DNA consists of two strands twisted into a double helix. RNA contains 4-6 thousand individual nucleotides, DNA - thousands. A gene is a section of a DNA or RNA molecule.
Cellular level At this level, there is a spatial delimitation and ordering of vital processes due to the division of functions between specific structures. The main structural and functional unit of all living organisms is the cell. The history of life on our planet began from this level of organization.
All living organisms are composed of cells and their waste products. New cells are formed by dividing preexisting cells. All cells are similar in chemical composition and metabolism. The activity of the organism as a whole is composed of the activity and interaction of individual cells.
In the 1830s. the cell nucleus was discovered and described. All cells consist of: 1) a plasma membrane that controls the transfer of substances from the environment to the cell and vice versa; 2) cytoplasm with a varied structure; 3) the cell nucleus, which contains genetic information.
Ontogenetic (organismic) level An organism is an integral unicellular or multicellular living system capable of independent existence. Ontogenesis is the process of individual development of an organism from birth to death, the process of realization of hereditary information.
Population - a set of individuals of the same species occupying a certain territory, reproducing itself for a long time and having a common genetic fund. A species is a set of individuals similar in structure and physiological properties, having a common origin, able to interbreed freely and give fertile offspring.
Biogeocenotic level Biogeocenosis, or ecological system (ecosystem) - a set of biotic and abiotic elements interconnected by the exchange of matter, energy and information, within which the circulation of substances in nature can take place.
Biogeocenosis is an integral self-regulating system, consisting of: 1) producers (producing), directly processing inanimate matter (algae, plants, microorganisms); 2) consumers of the first order - substance and energy are obtained through the use of producers (herbivores); 3) consumers of the second order (predators, etc.); 4) scavengers (saprophytes and saprophages) feeding on dead animals; 5) decomposers are a group of bacteria and fungi that decompose the remains of organic matter.
Federal Agency for Healthcare and Social
Test work in biology
Qualitative features of living matter. Levels of organization of the living.
The chemical composition of the cell (proteins, their structure and functions)
Completed by a student
1 course 195 groups
correspondence department
Faculty of Pharmacy
Chelyabinsk 2009
Qualitative features of living matter. Organizational levels of the living
Any living system, no matter how complex it is organized, consists of biological macromolecules: nucleic acids, proteins, polysaccharides, and other important organic substances. From this level, various vital processes of the organism begin: metabolism and energy conversion, transmission of hereditary information, etc.
The cells of multicellular organisms form tissues - systems of similar structure and functions of cells and intercellular substances associated with them. Tissues integrate into larger functional units called organs. The internal organs are characteristic of animals; here they are part of organ systems (respiratory, nervous, etc.). For example, the digestive system: the oral cavity, pharynx, esophagus, stomach, duodenum, small intestine, large intestine, anus. Such specialization, on the one hand, improves the functioning of the body as a whole, and on the other hand, it requires an increase in the degree of coordination and integration of various tissues and organs.
A cell is a structural and functional unit, as well as a unit of development for all living organisms living on Earth. At the cellular level, the transmission of information and the transformation of substances and energy are coupled.
The elementary unit of the organismic level is an individual, which is considered in development - from the moment of inception to the end of existence - as a living system. Organ systems emerge that are specialized to perform various functions.
A set of organisms of the same species, united by a common habitat, in which a population is created - a supraorganismic system. Elementary evolutionary transformations are carried out in this system.
Biogeocenosis - a set of organisms of different types and varying complexity of organization with the factors of their habitat. In the process of joint historical development of organisms of different systematic groups, dynamic, stable communities are formed.
The biosphere is the totality of all biogeocenoses, a system that encompasses all the phenomena of life on our planet. At this level, there is a circulation of substances and a transformation of energy associated with the vital activity of all living organisms.
Table 1. Levels of organization of living matter
Molecular
The initial level of organization of the living. The subject of research is molecules of nucleic acids, proteins, carbohydrates, lipids and other biological molecules, i.e. molecules in the cell. Any living system, no matter how complex it is organized, consists of biological macromolecules: nucleic acids, proteins, polysaccharides, and other important organic substances. From this level, various vital processes of the organism begin: metabolism and energy conversion, transmission of hereditary information, etc.
Cellular
Study of cells that act as independent organisms (bacteria, protozoa and some other organisms) and cells that make up multicellular organisms.
Fabric
Cells that have a common origin and perform similar functions form tissues. There are several types of animal and plant tissues with different properties.
Organ
In organisms, starting with coelenterates, organs (organ systems) are formed, often from tissues of various types.
Organic
This level is represented by unicellular and multicellular organisms.
Population-specific
Organisms of the same species, living together in certain areas, make up a population. Now on Earth there are about 500 thousand species of plants and about 1.5 million species of animals.
Biogeocenotic
It is represented by a set of organisms of different types, depending on each other to one degree or another.
Biosphere
The highest form of organization of the living. Includes all biogeocenoses associated with general metabolism and energy conversion.
Each of these levels is quite specific, has its own patterns, its own research methods. It is even possible to single out the sciences that conduct their research at a certain level of organization of living things. For example, at the molecular level, living things are studied by such sciences as molecular biology, bioorganic chemistry, biological thermodynamics, molecular genetics, etc. Although the levels of organization of living things stand out, they are closely related to each other and follow from one another, which speaks of the integrity of living nature.
Cell membrane. The surface apparatus of the cell, its main parts, their purpose
A living cell is a fundamental part of the structure of living matter. It is the simplest system that possesses the whole range of properties of living things, including the ability to transfer genetic information. The cell theory was created by German scientists Theodor Schwann and Matthias Schleiden. Its main position is the assertion that all plant and animal organisms consist of cells that are similar in structure. Research in the field of cytology has shown that all cells carry out metabolism, are capable of self-regulation and can transmit hereditary information. The life cycle of any cell ends either by division and continuation of life in a renewed form, or by death. At the same time, it turned out that cells are very diverse, they can exist as unicellular organisms or as part of multicellular organisms. The lifespan of cells may not exceed several days, or may coincide with the lifespan of the organism. The size of cells varies greatly: from 0.001 to 10 cm. Cells form tissues, several types of tissues - organs, groups of organs associated with the solution of any general problems are called systems of the body. Cells have a complex structure. It is separated from the external environment by a shell, which, being loose and loose, ensures the interaction of the cell with the outside world, the exchange of matter, energy and information with it. Cell metabolism serves as the basis for another of their most important properties - the preservation of stability, stability of the conditions of the internal environment of the cell. This property of cells, inherent in the entire living system, is called homeostasis. Homeostasis, that is, the constancy of the composition of the cell, is maintained by metabolism, that is, metabolism. Metabolism is a complex, multistage process that includes the delivery of initial substances into the cell, the production of energy and proteins from them, the removal of the produced useful products, energy and waste from the cell into the environment.
The cell membrane is the cell membrane that performs the following functions:
separation of the contents of the cell and the external environment;
regulation of metabolism between the cell and the environment;
the place of occurrence of some biochemical reactions (including photosynthesis, oxidative phosphorylation);
the union of cells into tissues.
The membranes are divided into plasma (cell membranes) and outer ones. The most important property of the plasma membrane is semi-permeability, that is, the ability to pass only certain substances. Glucose, amino acids, fatty acids and ions slowly diffuse through it, and the membranes themselves can actively regulate the diffusion process.
According to modern data, plasma membranes are lipoprotein structures. Lipids spontaneously form a bilayer, and membrane proteins "float" in it. There are several thousand different proteins in membranes: structural, carriers, enzymes, and others. It is assumed that there are pores between the protein molecules through which hydrophilic substances can pass (the lipid bilayer interferes with their direct penetration into the cell). Glycosyl groups are attached to some molecules on the membrane surface, which are involved in the process of cell recognition during tissue formation.
Different types of membranes differ in their thickness (usually it ranges from 5 to 10 nm). The consistency of the lipid bilayer resembles olive oil. Depending on external conditions (cholesterol is the regulator), the structure of the bilayer can change so that it becomes more liquid (the activity of the membranes depends on this).
Transport of substances across plasma membranes is an important problem. It is essential for the delivery of nutrients to the cell, the elimination of toxic waste products, and the creation of gradients to maintain nerve and muscle activity. There are the following mechanisms for the transport of substances through the membrane:
diffusion (gases, fat-soluble molecules penetrate directly through the plasma membrane); with facilitated diffusion, a water-soluble substance passes through the membrane through a special channel created by any specific molecule;
osmosis (diffusion of water through semi-permeable membranes);
active transport (the transfer of molecules from a region with a lower concentration to a region with a higher one, for example, by means of special transport proteins, requires the expenditure of ATP energy);
during endocytosis, the membrane forms invaginations, which are then transformed into vesicles or vacuoles. Distinguish between phagocytosis - the absorption of solid particles (for example, by blood leukocytes) - and pinocytosis - the absorption of liquids;
exocytosis is a process opposite to endocytosis; undigested residues of solid particles and liquid secretions are removed from the cells.
Above the plasma membrane of the cell, supramembrane structures can be located. Their structure is a wet classification feature. In animals it is a glycocalyx (protein-carbohydrate complex), in plants, fungi and bacteria, it is a cell wall. The cell wall of plants includes cellulose, fungi - chitin, bacteria - protein-polysaccharide complex murein.
The basis of the surface apparatus of cells (PAA) is the outer cell membrane, or plasmalemma. In addition to the plasmalemma, PAA contains a supramembrane complex, while eukaryotes also have a submembrane complex.
The main biochemical components of the plasmalemma (from the Greek. Plasma - formation and lemma - shell, crust) are lipids and proteins. Their quantitative ratio in most eukaryotes is 1: 1, while in prokaryotes, proteins predominate in the plasmalemma. A small amount of carbohydrates is found in the outer cell membrane and fat-like compounds (in mammals - cholesterol, fat-soluble vitamins) can be found.
The supramembrane complex of the surface apparatus of cells is characterized by a variety of structures. In prokaryotes, the supramembrane complex in most cases is represented by a cell wall of varying thickness, which is based on the complex glycoprotein murein (in archaea - pseudomurein). In a number of eubacteria, the outer part of the supramembrane complex consists of another membrane with a high content of lipopolysaccharides. In eukaryotes, the universal component of the supramembrane complex is carbohydrates - components of glycolipids and glycoproteins of the plasmalemma. Due to this, it was originally called glycocalyx (from the Greek glycos - sweet, carbohydrate and Latin callum - thick skin, shell). In addition to carbohydrates, the glycocalyx includes peripheral proteins above the bilipid layer. More complex variants of the supramembrane complex are found in plants (cellulose cell wall), fungi, and arthropods (chitin outer cover).
The submembrane (from Latin sub - sub) complex is characteristic only of eukaryotic cells. It consists of a variety of protein filamentous structures: thin fibrils (from the Latin fibril - filament, thread), microfibrils (from the Greek micro - small), skeletal (from the Greek skeleton - dried) fibrils and microtubules. They are linked to each other by proteins and form the musculoskeletal system of the cell. The submembrane complex interacts with proteins of the plasma membrane, which, in turn, are associated with the supramembrane complex. As a result, the PAK is a structurally integral system. This allows it to perform functions important for the cell: insulating, transport, catalytic, receptor-signaling and contact.
The chemical composition of the cell (proteins, their structure and functions)
Chemical processes in a cell are one of the basic conditions for its life, development, and functioning.
PAGE_BREAK--
All cells of plant and animal organisms, as well as microorganisms, are similar in chemical composition, which indicates the unity of the organic world.
Out of 109 elements of Mendeleev's periodic system, a significant majority of them are found in cells. Some elements are contained in cells in a relatively large amount, others - in a small amount (table 2).
Table 2. Content of chemical elements in the cell
The elements
Quantity (in%)
The elements
Quantity (in%)
Oxygen
In the first place among the substances of the cell is water. It makes up almost 80% of the cell mass. Water is the most important component of the cell, not only in terms of quantity. It plays an essential and diverse role in the life of the cell.
Water determines the physical properties of the cell - its volume, elasticity. The importance of water in the formation of the structure of molecules of organic substances, in particular the structure of proteins, which is necessary for the performance of their functions. The importance of water as a solvent is great: many substances enter the cell from the external environment in an aqueous solution, and waste products are removed from the cell. Finally, water is a direct participant in many chemical reactions (breakdown of proteins, carbohydrates, fats, etc.).
The biological role of water is determined by the peculiarity of its molecular structure, the polarity of its molecules.
The inorganic substances of the cell, in addition to water, also include salts. For vital processes, of the cations that make up the salts, the most important are K +, Na +, Ca2 +, Mg2 +, of the anions - HPO4-, H2PO4-, Cl-, HCO3-.
The concentration of cations and anions in the cell and in its environment is, as a rule, sharply different. As long as the cell is alive, the ratio of ions inside and outside the cell is steadily maintained. After the death of the cell, the content of ions in the cell and in the medium is quickly equalized. The ions contained in the cell are of great importance for the normal functioning of the cell, as well as for maintaining a constant reaction within the cell. Despite the fact that acids and alkalis are continuously formed in the process of vital activity, normally the reaction of the cell is weakly alkaline, almost neutral.
Inorganic substances are contained in the cell not only in a dissolved state, but also in a solid state. In particular, the strength and hardness of bone tissue is provided by calcium phosphate, and shellfish - by calcium carbonate.
Organic substances form about 20 - 30% of the cell composition.
Biopolymers include carbohydrates and proteins. The composition of carbohydrates includes atoms of carbon, oxygen, hydrogen. Distinguish between simple and complex carbohydrates. Simple - monosaccharides. Complex - polymers, the monomers of which are monosaccharides (oligosaccharides and polysaccharides). With an increase in the number of monomer units, the solubility of polysaccharides decreases, the sweet taste disappears.
Monosaccharides are solid, colorless crystalline substances that dissolve well in water and very poorly (or not at all) dissolve in organic solvents. Among monosaccharides, trioses, tetroses, pentoses and hexoses are distinguished. Among oligosaccharides, the most common are disaccharides (maltose, lactose, sucrose). Polysaccharides are most often found in nature (cellulose, starch, chitin, glycogen). Their monomers are glucose molecules. They partially dissolve in water, swelling to form colloidal solutions.
Lipids are water-insoluble fats and fat-like substances, consisting of glycerol and high molecular weight fatty acids. Fats are esters of the trihydric alcohol of glycerol and higher fatty acids. Animal fats are found in milk, meat, subcutaneous tissue. In plants - in seeds, fruits. In addition to fats, cells also contain their derivatives - steroids (cholesterol, hormones and fat-soluble vitamins A, D, K, E, F).
Lipids are:
structural elements of cell membranes and cell organelles;
energetic material (1 g of fat, being oxidized, releases 39 kJ of energy);
spare substances;
perform a protective function (in marine and polar animals);
affect the functioning of the nervous system;
a source of water for the body (1 kg, being oxidized, gives 1.1 kg of water).
Nucleic acids. The name "nucleic acids" comes from the Latin word "nucleus", i.e. nucleus: they were first found in cell nuclei. The biological significance of nucleic acids is very high. They play a central role in the storage and transmission of the hereditary properties of the cell, which is why they are often called hereditary substances. Nucleic acids provide in the cell the synthesis of proteins, exactly the same as in the mother cell and the transfer of hereditary information. There are two types of nucleic acids - deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
A DNA molecule consists of two spirally twisted chains. DNA is a polymer whose monomers are nucleotides. Nucleotides are compounds consisting of a phosphoric acid molecule, a deoxyribose carbohydrate and a nitrogenous base. DNA has four types of nitrogenous bases: adenine (A), guanine (G), cytosine (C), thymine (T). Each DNA strand is a polynucleotide consisting of several tens of thousands of nucleotides. Duplication of DNA - reduplication - ensures the transfer of hereditary information from the mother cell to the daughter.
RNA is a polymer, structurally similar to one DNA strand, but smaller. RNA monomers are nucleotides consisting of phosphoric acid, ribose carbohydrate and nitrogenous base. Instead of thymine, uracil is present in the RNA. There are three types of RNA: informational (i-RNA) - transfers information about the structure of a protein from a DNA molecule; transport (t-RNA) - transports amino acids to the site of protein synthesis; ribosomal (r-RNA) - contained in ribosomes, is involved in maintaining the structure of the ribosome.
A very important role in the bioenergetics of the cell is played by the adenyl nucleotide, to which two phosphoric acid residues are attached. This substance is called adenosine triphosphoric acid (ATP). ATP is a universal biological energy accumulator: the light energy of the sun and the energy contained in the food consumed are stored in the ATP molecules. ATP is an unstable structure; during the transition of ATP to ADP (adenosine diphosphate), 40 kJ of energy is released. ATP is formed in the mitochondria of animal cells and during photosynthesis in plant chloroplasts. ATP energy is used to perform chemical (synthesis of proteins, fats, carbohydrates, nucleic acids), mechanical (movement, muscle work) work, transformation into electrical or light (discharges of electric rays, eels, glow of insects) energy.
Proteins are non-periodic polymers, the monomers of which are amino acids. All proteins contain atoms of carbon, hydrogen, oxygen, nitrogen. Many proteins also contain sulfur atoms. There are proteins, which also include metal atoms - iron, zinc, copper. The presence of acidic and basic groups determines the high reactivity of amino acids. A water molecule is released from the amino group of one amino acid and the carboxyl of another, and the released electrons form a peptide bond: CO-NN (discovered in 1888 by Professor A.Ya.Danilevsky), therefore proteins are called polypeptides. Protein molecules are macromolecules. Many amino acids are known. But as monomers of any natural proteins - animal, plant, microbial, viral - only 20 amino acids are known. They are called "magic". The fact that proteins of all organisms are built from the same amino acids is another proof of the unity of the living world on Earth.
There are 4 levels of organization in the structure of protein molecules:
1. Primary structure - a polypeptide chain of amino acids linked in a specific sequence by covalent peptide bonds.
2. Secondary structure - a helical polypeptide chain. Numerous hydrogen bonds arise between the peptide bonds of adjacent turns and other atoms, providing a strong structure.
3. Tertiary structure - configuration specific for each protein - globule. Held by low-strength hydrophobic bonds or cohesion forces between non-polar radicals, which are found in many amino acids. There are also covalent S-S bonds arising between the radicals of the sulfur-containing amino acid cysteine, which are distant from each other.
4. A quaternary structure arises when several macromolecules combine to form aggregates. So, the hemoglobin of human blood is an aggregate of four macromolecules.
Violation of the natural structure of a protein is called denaturation. It occurs under the influence of high temperature, chemicals, radiant energy, and other factors.
The role of protein in the life of cells and organisms:
building (structural) - proteins - the building material of the body (shells, membranes, organelles, tissues, organs);
catalytic function - enzymes that accelerate reactions hundreds of millions of times;
musculoskeletal function - proteins that make up the bones of the skeleton, tendons; movement of flagellates, ciliates, muscle contraction;
transport function - blood hemoglobin;
protective - blood antibodies neutralize foreign substances;
energy function - when proteins are broken down, 1 g releases 17.6 kJ of energy;
regulatory and hormonal - proteins are part of many hormones and take part in the regulation of the body's life processes;
receptor - proteins carry out the process of selective recognition of individual substances and their attachment to molecules.
Cell metabolism. Photosynthesis. Chemosynthesis
A prerequisite for the existence of any organism is a constant influx of nutrients and a constant release of the end products of chemical reactions occurring in cells. Nutrients are used by organisms as a source of atoms of chemical elements (primarily carbon atoms), from which all structures are built or renewed. In addition to nutrients, the body also receives water, oxygen, and mineral salts.
Organic substances that enter the cells (or synthesized during photosynthesis) are broken down into building blocks - monomers and sent to all cells of the body. Some of the molecules of these substances are spent on the synthesis of specific organic substances inherent in a given organism. Cells synthesize proteins, lipids, carbohydrates, nucleic acids and other substances that perform various functions (building, catalytic, regulatory, protective, etc.).
Another part of the low-molecular-weight organic compounds that enter the cells goes to the formation of ATP, the molecules of which contain the energy intended directly for doing work. Energy is necessary for the synthesis of all specific substances of the body, maintaining its highly ordered organization, active transport of substances inside cells, from one cell to another, from one part of the body to another, for the transmission of nerve impulses, movement of organisms, maintaining a constant body temperature (in birds and mammals ) and for other purposes.
In the course of the transformation of substances in cells, end products of metabolism are formed, which can be toxic to the body and are removed from it (for example, ammonia). Thus, all living organisms constantly consume certain substances from the environment, transform them and release final products into the environment.
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The set of chemical reactions taking place in the body is called metabolism or metabolism. Depending on the general direction of the processes, catabolism and anabolism are distinguished.
Catabolism (dissimilation) is a set of reactions leading to the formation of simple compounds from more complex ones. For example, the reactions of hydrolysis of polymers to monomers and the cleavage of the latter to carbon dioxide, water, ammonia, i.e. reactions of energy metabolism, during which the oxidation of organic substances and the synthesis of ATP occurs.
Anabolism (assimilation) is a set of reactions for the synthesis of complex organic substances from simpler ones. These include, for example, nitrogen fixation and protein biosynthesis, the synthesis of carbohydrates from carbon dioxide and water during photosynthesis, the synthesis of polysaccharides, lipids, nucleotides, DNA, RNA and other substances.
The synthesis of substances in the cells of living organisms is often denoted by the concept of plastic metabolism, and the degradation of substances and their oxidation, accompanied by the synthesis of ATP, is denoted by energy metabolism. Both types of exchange form the basis of the vital activity of any cell, and therefore, of any organism, and are closely related to each other. On the one hand, all plastic exchange reactions require an expenditure of energy. On the other hand, for the implementation of reactions of energy metabolism, constant synthesis of enzymes is necessary, since their life expectancy is short. In addition, substances used for respiration are formed during plastic metabolism (for example, during photosynthesis).
Photosynthesis is the process of the formation of organic matter from carbon dioxide and water in the light with the participation of photosynthetic pigments (chlorophyll in plants, bacteriochlorophyll and bacteriorhodopsin in bacteria). In modern plant physiology, photosynthesis is more often understood as a photoautotrophic function - a combination of processes of absorption, conversion and use of the energy of light quanta in various endergonic reactions, including the conversion of carbon dioxide into organic substances.
Photosynthesis is the main source of biological energy, photosynthetic autotrophs use it to synthesize organic substances from inorganic ones, heterotrophs exist due to the energy stored by autotrophs in the form of chemical bonds, releasing it in the processes of respiration and fermentation. The energy received by humanity from the combustion of fossil fuels (coal, oil, natural gas, peat) is also stored in the process of photosynthesis.
Photosynthesis is the main entrance of inorganic carbon into the biological cycle. All free oxygen in the atmosphere is of biogenic origin and is a byproduct of photosynthesis. The formation of an oxidizing atmosphere (oxygen catastrophe) completely changed the state of the earth's surface, made possible the appearance of respiration, and later, after the formation of the ozone layer, allowed life to emerge on land.
Chemosynthesis is a method of autotrophic nutrition, in which the oxidation reactions of inorganic compounds serve as a source of energy for the synthesis of organic substances from CO2. This type of energy production is used only by bacteria. The phenomenon of chemosynthesis was discovered in 1887 by the Russian scientist S.N. Vinogradsky.
It should be noted that the energy released in the oxidation reactions of inorganic compounds cannot be directly used in the assimilation processes. First, this energy is converted into the energy of macroenergetic bonds of ATP and only then is it spent on the synthesis of organic compounds.
Chemolithoautotrophic organisms:
Iron bacteria (Geobacter, Gallionella) oxidize ferrous iron to ferric.
Sulfur bacteria (Desulfuromonas, Desulfobacter, Beggiatoa) oxidize hydrogen sulfide to molecular sulfur or to sulfuric acid salts.
Nitrifying bacteria (Nitrobacteraceae, Nitrosomonas, Nitrosococcus) oxidize ammonia formed during the decay of organic matter to nitrous and nitric acids, which interact with soil minerals to form nitrites and nitrates.
Thionic bacteria (Thiobacillus, Acidithiobacillus) are capable of oxidizing thiosulfates, sulfites, sulfides and molecular sulfur to sulfuric acid (often with a significant decrease in the pH of the solution), the oxidation process differs from that of sulfur bacteria (in particular, in that thionic bacteria do not deposit intracellular sulfur). Some representatives of thionic bacteria are extreme acidophiles (they are able to survive and multiply when the pH of the solution is lowered down to 2), they are able to withstand high concentrations of heavy metals and oxidize metallic and ferrous iron (Acidithiobacillus ferrooxidans) and leach heavy metals from ores.
Hydrogen bacteria (Hydrogenophilus) are able to oxidize molecular hydrogen, are moderate thermophiles (grow at 50 ° C)
Chemosynthetic organisms (for example, sulfur bacteria) can live in the oceans at great depths, in those places where hydrogen sulfide comes out of the fractures of the earth's crust into the water. Of course, quanta of light cannot penetrate into the water to a depth of about 3-4 kilometers (at this depth, most of the rift zones of the ocean are located). Thus, chemosynthetics are the only organisms on earth that do not depend on the energy of sunlight.
On the other hand, ammonia, which is used by nitrifying bacteria, is released into the soil when plant or animal remains decay. In this case, the vital activity of chemosynthetics indirectly depends on sunlight, since ammonia is formed during the decay of organic compounds obtained from the energy of the Sun.
The role of chemosynthetics for all living things is very great, since they are an indispensable link in the natural cycle of the most important elements: sulfur, nitrogen, iron, etc. Chemosynthetics are also important as natural consumers of toxic substances such as ammonia and hydrogen sulfide. Of great importance are nitrifying bacteria, which enrich the soil with nitrites and nitrates - it is mainly in the form of nitrates that plants assimilate nitrogen. Some chemosynthetics (in particular sulfur bacteria) are used for wastewater treatment.
According to current estimates, the biomass of the “underground biosphere”, which is located, in particular, under the seabed and includes chemosynthetic anaerobic methane-oxidizing archaebacteria, may exceed the biomass of the rest of the biosphere.
Meiosis. Features of the first and second division of meiosis. Biological significance. The difference between meiosis and mitosis
The understanding of the fact that sex cells are haploid and therefore must be formed using a special mechanism of cell division came as a result of observations, which, moreover, almost for the first time suggested that chromosomes contain genetic information. In 1883, it was discovered that the nuclei of the egg and the sperm of a certain type of worm contain only two chromosomes, while in a fertilized egg there are already four of them. The chromosomal theory of heredity could thus explain the long-standing paradox that the roles of the father and mother in determining the characteristics of offspring often seem to be the same, despite the huge difference in the size of the egg and sperm.
Another important implication of this discovery was that germ cells should be formed as a result of a special type of nuclear division, in which the entire set of chromosomes is divided exactly in half. This type of division is called meiosis (a word of Greek origin, meaning “decrease.” The name of another type of cell division - mitosis - comes from the Greek word meaning “thread”, this choice of name is based on the thread-like type of chromosomes during their condensation during nuclear division - this process occurs both during mitosis and during meiosis) The behavior of chromosomes during meiosis, when their number is reduced, turned out to be more complex than previously thought. Therefore, it was possible to establish the most important features of meiotic division only by the beginning of the 30s as a result of a huge number of careful studies that combined cytology and genetics.
During the first division of meiosis, each daughter cell inherits two copies of one of the two homologues and therefore contains a diploid amount of DNA.
The formation of gamete haploid nuclei occurs as a result of the second division of meiosis, in which chromosomes line up at the equator of a new spindle and, without further DNA replication, sister chromatids are separated from each other, as in ordinary mitosis, forming cells with a haploid set of DNA.
Thus, meiosis consists of two cell divisions, following a single phase of chromosome doubling, so that four haploid cells are obtained from each cell entering meiosis.
Sometimes the meiosis process proceeds abnormally, and homologues cannot separate from each other - this phenomenon is called chromosome nondisjunction. Some of the haploid cells formed in this case receive an insufficient number of chromosomes, while others acquire their extra copies. Defective embryos are formed from such gametes, most of which die.
In the prophase of the first division of meiosis during conjugation (synapsis) and separation of chromosomes, the most complex morphological changes occur in them. In accordance with these changes, the prophase is divided into five successive stages:
leptotene;
zygotene;
pachytene;
diplomat;
diakinesis.
The most striking phenomenon is the initiation of close convergence of chromosomes in the zygotene, when a specialized structure called a synaptonemal complex begins to form between pairs of sister chromatids in each bivalent. The moment of complete conjugation of chromosomes is considered the beginning of pachytene, which usually lasts several days; after chromosome separation, the stage of diplotene begins, when chiasmata are first visible.
After the end of the long prophase I, two nuclear fissions without a period of DNA synthesis separating them bring the process of meiosis to the end. These stages usually take no more than 10% of the total time required for meiosis, and they bear the same names as the corresponding stages of mitosis. In the remainder of the first division of meiosis, metaphase I, anaphase I and telophase I are distinguished. By the end of the first division, the chromosome set is reduced, turning from tetraploid to diploid, just like during mitosis, and two cells are formed from one cell. The decisive difference is that during the first division of meiosis, each cell receives two sister chromatids connected in the centromere region, and during mitosis, two separated chromatids.
Further, after a short-term interphase II, in which the chromosomes are not duplicated, the second division rapidly occurs - prophase II, anaphase II, and telophase II. As a result, four haploid nuclei are formed from each diploid cell that has entered meiosis.
Meiosis consists of two successive cell divisions, the first of which lasts almost as long as the entire meiosis, and is much more complex than the second.
After the end of the first division of meiosis, membranes are formed again in two daughter cells and a short interphase begins. At this time, the chromosomes are somewhat despiralized, but soon they condense again and prophase II begins. Since DNA synthesis does not occur during this period, it seems that in some organisms chromosomes go directly from one division to another. Prophase II is short in all organisms: the nuclear envelope is destroyed when a new spindle is formed, after which, rapidly replacing each other, metaphase II, anaphase II and telophase II follow. As in mitosis, kinetochore filaments are formed in sister chromatids, extending from the centromere in opposite directions. In the metaphase plate, two sister chromatids are held together until anaphase, when they separate due to the sudden separation of their kinetochores. Thus, the second division of meiosis is similar to ordinary mitosis, the only significant difference is that there is one copy of each chromosome, and not two, as in mitosis.
Meiosis ends with the formation of nuclear membranes around the four haploid nuclei formed in telophase II.
In general, as a result of meiosis, four haploid cells are formed from one diploid cell. In gamete meiosis, gametes are formed from the formed haploid cells. This type of meiosis is characteristic of animals. Gamete meiosis is closely related to gametogenesis and fertilization. In zygotic and spore meiosis, the formed haploid cells give rise to spores or zoospores. These types of meiosis are characteristic of lower eukaryotes, fungi, and plants. Spore meiosis is closely related to sporogenesis. Thus, meiosis is the cytological basis of sexual and asexual (spore) reproduction.
The biological significance of meiosis lies in maintaining the constancy of the number of chromosomes in the presence of a sexual process. In addition, as a result of crossing over, recombination occurs - the appearance of new combinations of hereditary inclinations in chromosomes. Meiosis also provides combinative variability - the appearance of new combinations of hereditary inclinations during further fertilization.
The course of meiosis is controlled by the genotype of the organism, under the control of sex hormones (in animals), phytohormones (in plants), and many other factors (for example, temperature).
The following types of influences of some organisms on others are possible:
positive - one organism benefits from another;
negative - the body is harmed because of another;
neutral - the other does not affect the body in any way.
Thus, the following variants of the relationship between two organisms are possible according to the type of their influence on each other:
Mutualism - in natural conditions, populations cannot exist without each other (example: symbiosis of a fungus and algae in a lichen).
Protocooperation - the relationship is optional (example: the relationship of a crab and anemones, anemones protect the crab and use it as a means of transportation).
Commensalism - One population benefits from a relationship and another gets no benefit or harm.
Cohabitation - one organism uses the other (or his dwelling) as a place of residence, without causing harm to the latter.
Freelogging - one organism feeds on food leftovers from another.
Neutralism - both populations do not affect each other in any way.
Amensalism, antibiosis - one population negatively affects another, but itself is not negatively influenced.
Predation is a phenomenon in which one organism feeds on the organs and tissues of another, while there is no symbiotic relationship.
Competition - both populations negatively affect each other.
Nature knows numerous examples of symbiotic relationships that benefit both partners. For example, the symbiosis between legumes and soil bacteria Rhizobium is extremely important for the nitrogen cycle in nature. These bacteria - they are also called nitrogen-fixing - settle on the roots of plants and have the ability to "fix" nitrogen, that is, to break down strong bonds between atoms of atmospheric free nitrogen, allowing nitrogen to be included in compounds available to plants, for example ammonia. In this case, the mutual benefit is obvious: the roots are the habitat of bacteria, and the bacteria supply the plant with the necessary nutrients.
There are also numerous examples of symbiosis that is beneficial to one species and not beneficial or harmful to another. For example, the human intestine is inhabited by many types of bacteria, the presence of which is harmless to humans. Likewise, plants called bromeliads (which include pineapple, for example) live on tree branches but get their nutrients from the air. These plants use the tree for support without depriving it of nutrients.
Flat worms. Morphology, taxonomy, main representatives. Development cycles. Infection routes. Prophylaxis
Flatworms are a group of organisms that, in most modern classifications, have the rank of type, uniting a large number of primitive worm-like invertebrates that do not have a body cavity. In its modern form, the group is clearly paraphyletic, but the current state of research does not make it possible to develop a satisfactory strictly phylogenetic system, and therefore zoologists traditionally continue to use this name.
The most famous representatives of flatworms are planaria (Turbellaria: Tricladida), liver fluke and cat fluke (trematodes), bovine tapeworm, pork tapeworm, broad tapeworm, echinococcus (tapeworms).
The question of the systematic position of the so-called intestinal turbellaria (Acoela) is currently under discussion, since in 2003 it was proposed to distinguish them as an independent type.
The body is bilaterally symmetric, with clearly defined head and tail ends, somewhat flattened in the dorsoventral direction, in large representatives it is strongly flattened. The body cavity is not developed (except for some phases of the life cycle of tapeworms and flukes). The exchange of gases is carried out across the entire surface of the body; respiratory organs and blood vessels are absent.
Outside, the body is covered with a single layer of epithelium. In ciliary worms, or turbellaria, the epithelium consists of cells that carry cilia. Flukes, monogeneans, cestodes and tapeworms are deprived of ciliary epithelium for most of their life (although ciliary cells can be found in larval forms); their integuments are represented by the so-called tegument, in a number of groups bearing microvilli or chitinous hooks. The tegument-bearing flatworms belong to the Neodermata group.
Under the epithelium is a muscular sac, consisting of several layers of muscle cells that are not differentiated into individual muscles (a certain differentiation is observed only in the region of the pharynx and genitals). The cells of the outer muscle layer are oriented transversely, the inner one - along the anteroposterior axis of the body. The outer layer is called the annular muscle layer, and the inner layer is called the longitudinal muscle layer.
In all groups, except for cestode and tapeworms, there is a pharynx leading into the intestine or, as in the so-called intestinal turbellaria, into the digestive parenchyma. The intestine is blindly closed and communicates with the environment only through the oral opening. Several large turbellaria have anal pores (sometimes several), but this is more the exception than the rule. In small forms, the intestine is straight, in large ones (planaria, flukes) it can branch strongly. The pharynx is located on the abdominal surface, often in the middle or closer to the posterior end of the body, in some groups it is displaced forward. In cestode and tapeworms, the intestine is absent.
The nervous system is of the so-called orthogonal type. Most have six longitudinal trunks (two on the dorsal and ventral sides of the body and two on the sides), interconnected by transverse commissures. Along with the orthogon, there is a more or less dense nerve plexus located in the peripheral layers of the parenchyma. Some of the most archaic representatives of ciliary worms have only a nerve plexus.
A number of forms have developed simple light-sensitive eyes, incapable of object vision, as well as organs of balance (stagocysts), tactile cells (sensilla), and organs of chemical sense.
Osmoregulation is carried out using protonephridia - branching canals that connect to one or two excretory canals. The release of toxic metabolic products occurs either with the fluid excreted through protonephridia, or by accumulation in specialized cells of the parenchyma (atrocytes), which play the role of "accumulation kidneys".
The overwhelming majority of representatives are hermaphrodites, except for blood flukes (schistosomes) - they are dioecious. Fluke eggs are light yellow to dark brown in color; one of the poles has a cap. When examined, eggs are found in the duodenal contents, feces, urine, sputum.
The first intermediate host among flukes are various mollusks, the second host is fish, amphibians. The final host is a variety of vertebrates.
The life cycle (by the example of polystyrene) is extremely simple: after leaving the fish, the larva emerges from the egg, which after a short period of time again sticks to the fish and turns into an adult worm. Flukes have a more complex development cycle, changing 2-3 hosts.
Genotype. Genome. Phenotype. Factors determining the development of the phenotype. Dominance and recessiveness. Interaction of genes in trait determination: dominance, intermediate manifestation, codominance
Genotype is a set of genes of a given organism, which, in contrast to the concepts of genome and gene pool, characterizes an individual, not a species (the difference between genotype and genome is the inclusion of non-coding sequences that are not included in the concept of genotype in the concept of genome). Together with environmental factors, it determines the phenotype of the organism.
Usually, a genotype is spoken of in the context of a particular gene; in polyploid individuals, it denotes a combination of alleles of a given gene. Most genes appear in the phenotype of an organism, but the phenotype and genotype are different in the following ways:
1. According to the source of information (the genotype is determined by studying the DNA of an individual, the phenotype is recorded by observing the appearance of the organism).
2. The genotype does not always correspond to the same phenotype. Some genes appear in the phenotype only under certain conditions. On the other hand, some phenotypes, such as animal fur coloration, are the result of the interaction of several genes.
Genome - the totality of all genes of an organism; its complete chromosome set.
It is known that DNA, which is the carrier of genetic information in most organisms and, therefore, forms the basis of the genome, includes not only genes in the modern sense of the word. Most of the DNA of eukaryotic cells is represented by non-coding ("redundant") nucleotide sequences that do not contain information about proteins and RNA.
Therefore, the genome of an organism is understood as the total DNA of the haploid set of chromosomes and each of the extrachromosomal genetic elements contained in an individual cell of the germ line of a multicellular organism. The genome sizes of organisms of different species differ significantly from each other, and at the same time, there is often no correlation between the level of evolutionary complexity of a biological species and the size of its genome.
Phenotyp is a set of characteristics inherent in an individual at a certain stage of development. The phenotype is formed on the basis of the genotype, mediated by a number of environmental factors. In diploid organisms, dominant genes appear in the phenotype.
Phenotype - a set of external and internal characteristics of an organism acquired as a result of ontogenesis (individual development)
Despite the seemingly strict definition, the concept of phenotype has some ambiguities. First, most of the molecules and structures encoded by genetic material are not visible in the external appearance of the organism, although they are part of the phenotype. For example, human blood groups. Therefore, an extended definition of phenotype should include characteristics that can be detected by technical, medical or diagnostic procedures. Further, more radical expansion may include acquired behavior or even the organism's influence on the environment and other organisms.
The phenotype can be defined as the "carry-over" of genetic information towards environmental factors. As a first approximation, we can talk about two characteristics of the phenotype: a) the number of directions of removal characterizes the number of environmental factors to which the phenotype is sensitive - the dimensionality of the phenotype; b) "range" of removal characterizes the degree of sensitivity of the phenotype to a given environmental factor. Together, these characteristics determine the richness and development of the phenotype. The more multidimensional the phenotype and the more sensitive it is, the further the phenotype is from the genotype, the richer it is. If we compare the virus, bacterium, roundworm, frog and humans, then the richness of the phenotype in this series grows.
Some of the characteristics of a phenotype are directly determined by the genotype, such as eye color. Others are highly dependent on the body's interactions with the environment - for example, identical twins can vary in height, weight, and other basic physical characteristics, despite carrying the same genes.
Phenotypic variance (defined by genotypic variance) is a basic prerequisite for natural selection and evolution. The organism as a whole leaves (or does not leave) offspring, therefore natural selection affects the genetic structure of a population indirectly through the contributions of phenotypes. There is no evolution without different phenotypes. At the same time, recessive alleles are not always reflected in the traits of the phenotype, but they persist and can be passed on to the offspring.
The factors on which phenotypic diversity, genetic program (genotype), environmental conditions and the frequency of random changes (mutations) depend are summarized in the following relationship:
genotype + environment + random changes → phenotype.
The ability of a genotype to form in ontogenesis, depending on environmental conditions, different phenotypes are called the reaction norm. It characterizes the share of the environment in the implementation of the feature. The wider the reaction rate, the greater the influence of the environment and the less the influence of the genotype in ontogenesis. Usually, the more varied the living conditions of a species, the wider its reaction rate.
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Dominance (dominance) is a form of relationship between alleles of one gene, in which one of them (dominant) suppresses (masks) the manifestation of the other (recessive) and thus determines the manifestation of a trait in both dominant homozygotes and heterozygotes.
With complete dominance, the phenotype of the heterozygote does not differ from the phenotype of the dominant homozygote. Apparently, in its pure form, complete dominance is extremely rare or does not occur at all.
In case of incomplete dominance, heterozygotes have a phenotype intermediate between the phenotypes of the dominant and recessive homozygote. For example, when crossing pure lines of snapdragon and many other flowering plant species with purple and white flowers, the first generation has pink flowers. At the molecular level, the simplest explanation for incomplete dominance can be just a twofold decrease in the activity of an enzyme or another protein (if the dominant allele produces a functional protein, and the recessive allele produces a defective one). There may be other mechanisms of incomplete dominance.
In case of incomplete dominance, the same splitting by genotype and phenotype will be in a ratio of 1: 2: 1.
With codominance, in contrast to incomplete dominance, in heterozygotes, the traits for which each of the alleles is responsible appear simultaneously (mixed). A typical example of codominance is the inheritance of blood groups of the ABO system in humans. All offspring of people with genotypes AA (second group) and BB (third group) will have genotype AB (fourth group). Their phenotype is not intermediate between the phenotypes of the parents, since both agglutinogens (A and B) are present on the surface of erythrocytes. When codominating, one of the alleles cannot be called dominant, and the other cannot be recessive, these concepts lose their meaning: both alleles equally affect the phenotype. At the level of RNA and protein products of genes, apparently, the vast majority of cases of allelic interactions of genes is codominance, because each of the two alleles in heterozygotes usually encodes RNA and / or protein product, and both proteins or RNA are present in the body.
Environmental factors, their interaction
An environmental factor is a habitat condition that affects the body. The environment includes all bodies and phenomena with which the organism is in direct or indirect relations.
One and the same environmental factor has different meanings in the life of organisms living together. For example, the salt regime of the soil plays a primary role in the mineral nutrition of plants, but is indifferent for most land animals. The intensity of illumination and the spectral composition of light are extremely important in the life of phototrophic plants, and in the life of heterotrophic organisms (fungi and aquatic animals), light does not significantly affect their vital activity.
Environmental factors affect organisms in different ways. They can act as stimuli causing adaptive changes in physiological functions; as constraints that make it impossible for certain organisms to exist under given conditions; as modifiers that determine morphological and anatomical changes in organisms.
It is customary to distinguish biotic, anthropogenic and abiotic environmental factors.
Biotic factors - all the many environmental factors associated with the activity of living organisms. These include phytogenic (plants), zoogenic (animals), microbiogenic (microorganisms) factors.
Anthropogenic factors - all the many factors associated with human activities. These include physical (the use of atomic energy, movement in trains and airplanes, the effect of noise and vibration, etc.), chemical (the use of mineral fertilizers and pesticides, pollution of the earth shells with industrial and transport waste; smoking, alcohol and drug use, excessive use of medicinal means), biological (food; organisms for which a person can be a habitat or a source of food), social (associated with relationships between people and life in society) factors.
Abiotic factors - all the many factors associated with processes in inanimate nature. These include climatic (temperature, humidity, pressure), edaphogenic (mechanical composition, air permeability, soil density), orographic (relief, height above sea level), chemical (gas composition of air, salt composition of water, concentration, acidity), physical (noise, magnetic fields, thermal conductivity, radioactivity, cosmic radiation).
With the independent action of environmental factors, it is sufficient to operate with the concept of "limiting factor" in order to determine the joint effect of a complex of environmental factors on a given organism. However, in real conditions, environmental factors can enhance or weaken the action of each other.
Taking into account the interaction of environmental factors is an important scientific problem. There are three main types of interaction of factors:
additive - the interaction of factors is a simple algebraic sum of the effects of each of the factors with an independent action;
synergistic - the combined action of factors enhances the effect (that is, the effect when they act together is greater than the simple sum of the effects of each factor when acting independently);
antagonistic - the combined effect of factors weakens the effect (that is, the effect when they act together is less than the simple sum of the effects of each factor).
List of used literature
Gilbert S. Developmental Biology. - M., 1993.
Green N., Stout W., Taylor D. Biology. - M., 1993.
Nebel B. Environmental Science. - M., 1993.
Carroll R. Paleontology and evolution of vertebrates. - M., 1993.
Leinger A. Biochemistry. - M., 1974.
A. A. Slyusarev Biology with general genetics. - M., 1979.
Watson D. Molecular Biology of the Gene. - M., 1978.
Chebyshev N.V., Supryaga A.M. The simplest. - M., 1992.
Chebyshev N.V., Kuznetsov S.V. Cell biology. - M., 1992.
Yarygin V.N. Biology. - M., 1997.
Levels of organization of living matter Levels of organization of living matter. Author: Lysenko Roman, Pupil of grade 10 MBOU SOSH 31 Novocherkassk Biology teacher: Bashtannik N.E academic year
The molecular level is the level of functioning of biological macromolecules - biopolymers: nucleic acids, proteins, polysaccharides, lipids, steroids. The most important life processes begin from this level: metabolism, energy conversion, transmission of hereditary information. This level is studied by: biochemistry, molecular genetics, molecular biology, genetics, biophysics.
The cellular level 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. (Nerve cell)
The organismic level 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 is the level of aggregates of individuals - populations and species. This level is studied by systematics, taxonomy, ecology, biogeography, and population genetics. At this level, the genetic and ecological characteristics of populations, elementary evolutionary factors and their influence on the gene pool (microevolution), the problem of species conservation are studied.
Ecosystem level is the level of micro ecosystems, meso ecosystems, macro ecosystems. At this level, the types of nutrition, the types of relationships between organisms and populations in the ecosystem, the number of populations, the dynamics of the number of populations, the density of populations, the productivity of ecosystems, and succession are studied. This level is studied by ecology.
*1 – 4 *2 – 3 *3 – 1 *4 – 3 *5 - 3 *6 – 4 *7 – 1 *8 – 3 *9 – 2 *10 – 1 *
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