Chemical elements and inorganic compounds in accordance with the percentage in the cell are divided into three groups:
macroelements: hydrogen, carbon, nitrogen, oxygen (cell concentration - 99.9%);
trace elements: sodium, magnesium, phosphorus, sulfur, chlorine, potassium, calcium (concentration in cell -0.1%);
ultramicroelements: Bor, silicon, vanadium, manganese, iron, cobalt, copper, zinc, molybdenum (cell concentration - less than 0.001%).
Minerals, salts and ions make up 2 ... 6 % The volume of the cell, some mineral components are present in the cell in the non-ionized form. For example, iron associated with carbon is contained in hemoglobin, ferrity, cytochromas and other enzymes needed to maintain normal cell activity.
Mineral salts dissociated on anions and cations and thereby maintain osmotic pressure and acid-base equilibrium cells. Inorganic ions serve the cofactors needed to implement enzymatic activity. From the inorganic phosphate is formed in the process of oxidative phosphorylation of adenosine trifhosphate (ATP) - a substance in which the energy required for the vital activity of the cell is reserves. Calcium ions are in circulating blood and in cells. In the bones, they are in compound with phosphate and carbonate ions form a crystal structure.
Water - This is a universal dispersion environment of living matter. Active cells consist of 60-95% of the water, however, in resting cells and tissues, for example, in disputes and seeds, the water share is usually at least 10-20 %>. In a cage, water is in two forms: free and related. Free water is 95% of all water in the cell and is mainly used as a solvent and dispersion medium of the colloidal system of protoplasm. Related water (4-5 % All the water cells) is fragile with the proteins of hydrogen and other connections.
Organic substances - compounds containing carbon (except carbonates). Most organic substances are polymers consisting of repetitive particles - monomers.
Proteins - Biological polymers that make up the bulk of the organic substances of the cell, which account for about 40 ... 50% of the dry mass of protoplasm. Proteins contain carbon, hydrogen, oxygen, nitrogen, as well as sulfur and phosphorus.
Proteins consisting only of amino acids are called simple - proteins (from prtos - the first, most important). They usually laid in a cage as a spare substance. Complex proteins (proteids) are formed as a result of a compound of simple proteins with carbohydrates, fatty acids, nucleic acids. Protear nature has most enzymes that determine and regulate all life processes in the cell.
Depending on the spatial configuration, four structural levels of the organization of protein molecules are distinguished. Primary structure: Amino acids are risen as beads on the thread, the location sequence has an important biological value. Secondary structure: Molecules are compact, rigid, not elongated particles, such proteins are reminded by a spiral on the configuration. Tertiary structure: polypeptide chains as a result of complex spatial laying form a compact structure of the so-called globular proteins. Quaternary structure: consists of two or more chains that may be the same or different.
Proteins consist of monomers - amino acids (from the known 40 amino acids 20 are part of proteins). Amino acids - amphoteric compounds containing at the same time acid (carboxyl) and basic (amine) group. When condensation of amino acids leading to the formation of a protein molecule, a sour group of one amino acid is connected to the main group of another amino acid. Each protein contains hundreds of amino acid molecules connected in various directions and ratios, which determines the variety of functions of protein molecules.
Nucleic acids - Natural high molecular weight biological polymers providing storage and transmission of hereditary (genetic) information in living organisms. This is the most important group of biopolymers, although the content does not exceed 1-2% of the mass of protoplasm.
Nucleic acid molecules are long linear chains consisting of monomers - nucleotides. Each nucleotide contains a nitrogen base, monosaccharide (pentose) and the residue of phosphoric acid. The main amount of DNA is contained in the kernel, RNA is both in the kernel and in the cytoplasm.
Single-stranded ribonucleic acid molecule (RNA) has 4 ... 6 thousand nucleotides consisting of ribose, phosphoric acid residue and four types of nitrogen bases: adherent (a), guanin (g), uracil (y) and cytosine (C ).
DNA molecules consist of 10 ... 25 thousand separate nucleotides constructed from deoxyribose, phosphoric acid residue and four types of nitrogen bases: adenine (a), guanine (g), uracil (y) and thymine (T).
The DNA molecule consists of two complementary chains, the length of which reaches several tens and even hundreds of micrometers.
In 1953, D. Watson and F. Creek offered a spatial molecular DNA model (double spiral). DNA is able to carry genetic information and accurately reproduced - this is one of the most significant discoveries in the biology of the XX century, which has allowed to explain the mechanism of heredity and the given powerful impetus to the development of molecular biology.
Lipids - Zeper-like substances, varied in structure and functions. Simple lipids - fats, wax - consist of residual fatty acids and alcohols. Complex lipids are lipid complexes with proteins (lipoproteins), orthophosphoric acid (phospholipids), sugars (glycolipids). Usually they are contained in the amount of 2 ... 3%. Lipids are the structural components of the membranes affecting their permeability, as well as employees of the energy reserve for the formation of ATP.
The physical and chemical properties of lipids are determined by the presence in their molecules as polar (electrically charged) groups (-son, -on, -nh, etc.) and non-polar hydrocarbon chains. Thanks to this structure, most lipids are surfactants. They are very poorly soluble in water (due to the high content of hydrophobic radicals and groups) and in oils (due to the presence of polar groups).
Carbohydrates - organic compounds that are subdivided into monosaccharides (glucose, fructose), disaccharides (sucrose, maltose, etc.), polysaccharides (starch, glycogen, etc.). Monosaccharides - primary photosynthesis products are used for polysaccharide biosynthesis, amino acids, fatty acids, etc. Polysaccharides are reserved as an energy reserve with subsequent splitting of the freed monosaccharides in fermentation or respiratory processes. Hydrophilic polysaccharides maintain a water balance of cells.
Adenosine trifosphoric acid (ATP) consists of a nitrogen base - adenine, carbohydrate ribose and three residues of phosphoric acid, between which macroeergic bonds exist.
Proteins, carbohydrates and fats are not only building material from which the body is composed, but also energy sources. Oxidizing in the process of respiration proteins, carbohydrates, fats, the body turns the energy of complex organic compounds into rich communication energy in the ATP molecule. ATP is synthesized in mitochondria, and then enters different sections of the cell, providing energy all the processes of vital activity.
All living organisms consist of cells. The human body also has cellular structureThanks to which its growth, reproduction and development is possible.
The human body consists of a huge number of cells of different shapes and sizes that depend on the function being performed. Study cage buildings and functions Engaged cytology.
Each cell is coated consisting of several layers of a membrane molecules, which provides selective permeability of substances. Under the membrane in the cell is a viscous semi-liquid substance - cytoplasm with organoids.
Mitochondria - Energy stations of cells, ribosomes - the place of the formation of a protein, an endoplasmic network that performs the function of transporting substances, the kernel - the storage location of hereditary information, inside the nucleus - nucleoschko. It produces ribonucleic acid. Near the kernel is the cell center required when dividing the cell.
Cells of man Consist of organic and inorganic substances.
Inorganic substances:
Water is 80% of the cell mass, dissolves substances, participates in chemical reactions;
Mineral salts in the form of ions - participate in the distribution of water between cells and the intercellular substance. They are necessary for the synthesis of vital organic substances.
Organic substances:
Proteins are basic cell substances, the most complex of the substances found in nature. Proteins are part of the membranes, kernels, organoids, are performed in the cell structural function. Enzymes - proteins, reaction accelerators;
Fats - carry out the energy function, they are part of the membrane;
Carbohydrates - Also, when splitting, a large amount of energy is formed, well soluble in water and therefore, when they split, the energy is formed very quickly.
Nucleic acids - DNA and RNA, they determine, stored and transmit inheritance information about the composition of cell proteins from parents to offspring.
Cells of the human body have a number of vital properties and perform certain functions:
IN cells are metabotaccompanied by the synthesis and decay of organic compounds; The exchange of substances is accompanied by the conversion of energy;
When substances are formed in the cage, it grows, cell growth is associated with an increase in their number, this is associated with reproduction by division;
Live cells have excitability;
One of the characteristic features of the cell is movement.
Cage of the human body Inherent in the following life properties: metabolism, growth, reproduction and excitability. Based on these functions, the functioning of a whole organism is carried out.
Chemical composition of the cell.
The main properties and levels of the organization of wildlife
The levels of the organization of living systems reflect the cooding, the hierarchy of the structural organization of life:
Molecular genetic - separate biopolymers (DNA, RNA, proteins);
Cellular - elementary self-reproducing unit of life (prokaryotes, single-cell eukaryotes), fabrics, organs;
Organizable - independent existence of a separate individual;
Population-species - elementary evolving unit - population;
Biogenotic - ecosystems consisting of different populations and their habitats;
Biosphere - all the living population of the Earth, providing a circulation of substances in nature.
Nature is the entire existing material world in all the variety of its forms.
The unity of nature is manifested in the objectivity of its existence, the community of elemental composition, subordination to the same physical laws, in the system of organization.
Various natural systems, both alive and inanimate, are interrelated and interact with each other. An example of systemic interaction is a biosphere.
Biology is a complex of sciences that study the patterns of development and livelihoods of living systems, the causes of their diversity and environmental adaptability, relationship with other living systems and objects of inanimate nature.
The object of study of biology is wildlife.
The subject of biology research is:
General and private laws of the organization, development, metabolism, transmission of inheritance information;
A variety of forms of life and organisms themselves, as well as their connection with the environment.
All variety of life on Earth is explained by the evolutionary process and environmental action on organisms.
The essence of life is determined by M.V.
Volkenstein as an existence on the ground "live bodies, which are open self-regulating and self-reproducing systems built from biopolymers - proteins and nucleic acids."
The main properties of living systems:
Metabolism;
Self-regulation;
Irritability;
Variability;
Heredity;
Reproduction;
Chemical composition of the cell.
Inorganic cells cells
Cytology is a science that studies the structure and function of cells. The cell is an elementary structural and functional unit of living organisms. Unicellular organisms are inherent in all properties and functions of living systems.
Cells of multicellular organisms are differentiated in structure and functions.
Atomic composition: The cell includes about 70 elements of the periodic system of Mendeleev elements, and 24 of them are present in all types of cells.
Macroelements - N, O, N, C, trace elements - Mg, Na, Ca, Fe, K, P, Ci, S, ultramic-elements - Zn, Cu, I, F, Mn, CO, Si, etc.
Molecular composition: The cell includes molecules of inorganic and organic compounds.
Inorganic cells cells
Water molecule has a nonlinear spatial structure and has polarity. Between individual molecules, hydrogen bonds are formed, which determine the physical and chemical properties of water.
1. Water molecule Fig. 2. Hydrogen bonds between water molecules
Physical properties of water:
Water can be in three states - liquid, solid and gaseous;
Water is a solvent. Polar water molecules dissolve polar molecules of other substances. Substances soluble in water are called hydrophilic. Substances that are not soluble in water - hydrophobic;
High specific heat. For the breaking of hydrogen bonds holding water molecules, it is necessary to absorb a large amount of energy.
This property of water ensures the maintenance of the heat balance in the body;
High heat booth. For evaporation of water, quite large energy is necessary. Water boiling point is higher than many other substances. This property of water protects the body from overheating;
Water molecules are in constant motion, they face each other in the liquid phase, which is important for the metabolism processes;
Clutch and surface tension.
Hydrogen bonds determine the viscosity of water and the adhesion of its molecules with molecules of other substances (cohesion).
Due to the forces of the clutch of molecules on the surface of the water, a film is created, which characterizes the surface tension;
Density. When cooling, the movement of water molecules slows down. The amount of hydrogen bonds between molecules becomes maximum. The greatest density of water has at 4 ° C. Freezing, water expands (a place for the formation of hydrogen bonds), and its density decreases, so the ice floats on the surface of the water, which protects the water from freezing;
The ability to form colloidal structures.
Water molecules form around insoluble molecules of some substances a shell that prevents the formation of large particles. Such a state of these molecules is called dispersed (scattered). The smallest particles of substances surrounded by water molecules form colloidal solutions (cytoplasm, intercellular fluids).
Biological functions of water:
Transport - water provides the movement of substances in the cell and the body, the absorption of substances and the elimination of metabolic products.
In nature, water tolerates products of life in soil and to water bodies;
Metabolic - water is a medium for all biochemical reactions and electron donor with photosynthesis, it is necessary for hydrolysis macromolecules to their monomers;
Participate in education:
1) lubricating liquids that reduce friction (synovial - in the joints of vertebrate animals, pleural, in the pleural cavity, pericardial - in the window-shaped bag);
2) mucues that facilitate the movement of substances by intestines create a wet medium on the mucous membranes of the respiratory tract;
3) secrets (saliva, tears, bile, sperm, etc.) and juices in the body.
Inorganic ions.
Inorganic cell ions are presented: K +, Na +, Ca2 +, Mg2 +, NH3 cations and anions, CL, NOI2-, H2PO4-, HCO3-, HPO42-.
The difference between the number of cations and anions on the surface and inside the cell provides the occurrence of the potential of action, which underlies the nervous and muscle excitation.
Phosphoric acid anions create a phosphate buffer system that supports the pH of the intracellular medium of the body at 6-9.
Coalic acid and its anions create a bicarbonate buffer system and maintain the pH of the extracellular medium (blood plasma) at 4-7.
Nitrogen compounds serve as a source of mineral nutrition, protein synthesis, nucleic acids.
Phosphorne atoms are part of nucleic acids, phospholipids, as well as vertebrate bones, chitine cover arthropods. Calcium ions are part of the bones substance, they are also necessary for the implementation of muscle contraction, blood coagulation.
Chemical composition of the cell. Inorganic substances
Atomic and molecular composition of the cell. The microscopic cell contains several thousand substances that are involved in a variety of chemical reactions. Chemical processes, pro-target in the cell, are one of the main conditions for its life, development, operation.
All cells of animals and vegetable organisms, as well as microorganisms similar to the chemical composition, which is indicative of the unity of the organic world.
The table shows the data on the atomic composition of the cells.
Of the 109 elements of the periodic Mendeleev system in the cells, their majority were found. Some elements are contained in cells in a relatively large quantity, others. Especially great content in the cell of four elements - oxygen, carbon, nitrogen and hydrogen. In sum, they are almost 98% of the entire cell content. The next group is eight elements, the content of which in the cell is calculated with tenth and hundredths of the percent. It is sulfur, phosphorus, chlorine, potassium, magnesium, sodium, calcium, iron.
In sum, they make up 1.9%. All other elements are contained in a cage in exceptionally small quantities (less than 0.01%).
Thus, there are no special elements in the cell characteristic only for wildlife. This indicates the connection and unity of living and inanimate nature.
At the atomic level, there are no differences between the chemical composition of organic and inorganic world. Differences are detected at a higher level of organization - molecular.
As can be seen from the table, in the living bodies, along with substances common in non-people, there are many substances characteristic only for living organisms.
Water. In the first place among the substances of the cell is water. It is almost 80% of the mass of the cell. Water is the most important component of cells not only in quantity. It belongs to the essential and diverse role in the life of the cell.
Water determines the physical properties of the cell - its volume, the elbow.
The value of water in the formation of the structure of organic substances molecules, in particular the protein structures, which is necessary to perform their functions. The value of water as a solvent is great: many substances come into a cage from an external medium in aqueous solution and in the aqueous solution of waste products are derived from the cell.
Finally, water is a non-mediocre participant in many chemical reactions (ras-chopping proteins, carbohydrates, fats, etc.).
The cell's fitness to function in the aquatic environment serves as an argument in favor of the fact that life on Earth originated in water.
The biological role of water is determined by the peculiarity of its molecular structure: the polarity of its molecules.
Carbohydrates.
Carbohydrates are complex organic compounds, their composition includes carbon, oxygen and hydrogen atoms.
Distinguish simple and complex carbohydrates.
Simple carbohydrates are called monosaccharides. Complex carbohydrates represent the co-battle of polymers in which monosaccharides play the role of monomers.
Of the two monosaccharides, Disaccharide is formed, from three - Tris-Harid, from many - polysaccharide.
All monosaccharides are colorless substances, well soluble in water. Almost all of them possess a pleasant sweet taste. The most common monosaccharides are glucose, fructose, ribosis and deoxyribosis.
2.3 Chemical composition of the cell. Macro and microelements
The sweet taste of fruits and berries, as well as honey depends on the content of glucose and fructose in them. Ribosis and deoxyribosis are included in the composition of nucleic acids (p. 158) and ATP (s.
Di- and trisaccharides, like monosaccharides, are well soluble in water, they have a sweet taste. With an increase in the number of monomer units, solubility of polysaccharides decreases, sweet taste disappears.
Beet (or cane) and milk sugar are important from disaccharides, collapse-small (in plants), glycogen (in animals), fiber (cellulo) are widespread from polysaccharides.
Wood - almost pure cellulose. The monomers of these polysaccharides is glucose.
The biological role of carbohydrates. Carbohydrates play the role of the sour-nick energy required for the occasion of the cell of the various forms of activity. For cell activity - movement, secretion, biosynthesis, glow, etc. - Energy is necessary. Complicated by the structure rich in energy, carbohydrates are subjected to deep cleavage cells and result in simple, poor compound energy - carbon oxide (IV) and water (CO2 and H20).
During this process, energy is exempt. When splitting 1 g of carbohydrate is released 17.6 kJ.
In addition to energy, carbohydrates perform the construction function. For example, from cellulose consist of walls of plant cells.
Lipids. Lipids are contained in all cells of animals and plants. They are part of many cellular structures.
Lipids are organic substances, non-violent in water, but soluble in gasoline, ether, acetone.
From lipids the most common and known - fats.
There are, however, cells in which about 90% fat. In animals, such cells are under the skin, in breast glands, a seller. Fat is contained in the milk of all mammals. In some plants, a large amount of fat is concentrated in seeds and fruits, for example, sunflower, hemp, walnut.
In addition to fats in cells there are other lipids, for example, lecithin, cholesterol. Lipids include some Vi-Tamines (A, O) and hormones (for example, sex).
The biological value of lipids is large and diverse.
We note, first of all, their construction function. Lipids Hydro Fashion. The thinnest layer of these substances is part of cell membranes. The value of the most common from lipi-dove is fat - as an energy source. Fats are capable of oxidizing in a cell to carbon oxide (IV) and water. During the splitting of fat is released twice as much energy than when the carbohydrate cleavage. Animals and plants lay fat in stock and spend it in the course of life.
It is necessary to mark the following value. Fat as a source of water. Of 1 kg of fat, almost 1.1 kg of water is formed during its oxidation. This explains how some animals are so good to do quite considerable time without water. Verb-Luda, for example, the transition through anhydrous empty-nude may not drink within 10-12 days.
Bears, Surki and other animals in hibernation do not drink more than two months. You need these animals for life for life, these animals are obtained as a result of oxidation of fat. In addition to structural and energy functions, lipids perform protective functions: fat has low thermal conductivity. It is postponed under the skin, in some animals, significant clusters. So, in China, the thickness of the subcutaneous layer of fat reaches 1m, which allows this animal to live in the cold water of the polar seas.
Biopolymers: proteins, nucleic acids.
Of all organic substances, the bulk of the cell (50-70%) co-put proteins.Cell shell and all its internal structures are built-with the participation of protein molecules. The protein molecules are very large because they consist of many hundreds of various monomers forming all sorts of combo nations. Therefore, the diversity of species of proteins and their properties are truly infinite.
Proteins are part of hair, feathers, horns, muscle fibers, feed
eggs and seeds and many other parts of the body.
Protein molecule - polymer. Monomers of protein molecules are AMI-Nokslots.
More than 150 different amino acids are known in nature, but in the construction of live organisms, only 20 people are usually involved. The long thread consistently attached to each other amino acids represents primary structureprotein molecules (it displays its chemical formula).
Usually, this long thread is tightly twisted into a spiral whose coils are still interconnected by hydrogen bonds.
Spiral twisted thread of the molecule is secondary structure, moleculessquirrel. Such a protein is fixed to stretch. The protein molecule rolled into the spiral is then twisted a more dense configuration - tertiary structure.Some Bel-Cov have an even more complex form - quaternary structurefor example, hemoglobin. As a result of this multiple twisting, the long and thin thread of the protein molecule becomes shorter, thicker and is going to a closet lump - globulu Only the globular protein performs its biological functions in the cell.
If you break the structure of the protein, for example, heating or chemical action, then it loses its qualities and is spinning.
This process is named denatura. If denaturation affected only the tertiary or secondary structure, then it is reversible: it can be replaced again into the spiral and put into a three-tich structure (the phenomenon of denaturation). The functions of this protein are restored. This is the most important property of proteins underlies the irritability of living systems, i.e.
the abilities of living cells respond to external or internal irritants.
Many proteins perform a role catalystsin chemical reactions,
cage passing.
They are called enzymes.Enzymes are involved in the re-nose of atoms and molecules, in splitting and constructing proteins, fats, carbohydrates and all other compounds (i.e., in cellular metabolism). No chi-mile reaction in living cells and fabrics do without the participation of farm.
All enzymes have specificity of action - streamline processes or accelerate reactions in the cell.
Proteins in the cell perform many functions: participate in its stricture, growth and in all processes of vital activity. Without proteins, the life of the cell is impossible.
Nucleic acids were first discovered in cell nuclei, in connection with which they received their name (lat.
psleus - kernel). There are two types of nucleic acids: deoxyribonucleic acid (abbreviated dick) and ribonucleic acid (REC). Nucleic acid molecules
put very long polymer chains (trash), monomers
which are nucleotides.
Each nucleotide contains in itself along a one molecule of phosphoric acid and sugar (deoxyribose or ribose), as well as one of four nitrogen bases. Nitrogen bases at DNA are adenin Guanin and CMUMUN,and mI Min,.
Deoxyribonucleic Acid (DNA)- The most important substance in a living cage. DNA molecule is a carrier of hereditary cell information and an organism as a whole. From the DNA molecule is formed chromosome.
At the organ-dullness of each biological species, a certain amount of DNA molecules per cell. The sequence of nucleotides in the DNA molecule is also always strictly individual and. Unique not only for each biological species, but also for individual individuals.
Such specificity of DNA molecules is the basis for establishing the relative proximity of organisms.
DNA molecules in all eukaryotes are in the core of the cell. Prokaryotus does not have a nucleus, so their DNA is located in the cytoplasm.
all living beings of DNA macromolecules are built one by one and the same type. They consist of two polynucleotide chains (heavy), fastening with each other with hydrogen bonds of nitrogen bases of nucleoti-dov (like the zipper clasp).
In the form of a double (steam room), the helix mole-kula DNA twisted in the direction from left to right.
The sequence in the location of nucleotides in the DIC molecule determines the cell's hereditary information.
The structure of the DNA molecule was uncovered in 1953. American biochemist
James Watson and the English physicist Francis Creek.
For this discovery, scientists were awarded in 1962 of the Nobel Prize. They proved that molecule
DNA consists of two polynucleotide chains.
In this case, nucleotides (mono-measures) are connected to each other not by chance, but selectively and vapors by means of nitrogenous compounds. Aden in (a) is always joined with thymine (T), and guanine (g) - with cytosine (C). This double chain is tightly spinled in a spoal. The ability of nucleotides to the electoral connection to the pair is called complementarity(Lat. Complempentus - addition).
Replication occurs as follows.
With the participation of special cellular mechanisms (enzymes), the double helix of DNA is unchecked, the threads are raised (like the "lightning" is unbounded), and gradually, half of the corresponding nucleotides are completed to each of the two chains.
8 A result, instead of one DNA molecule, two but-you are formed by the same identical molecules. With that, each newly formed double-stranded molecule of DNA consists of one "old" chain of nucleotides and one "new".
Since DNA is the main carrier of information, then its ability to double allows the cell to transmit that hereditary in-formation into newly formed subsidiaries.
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Buffoff and osmosis.
Salts in living organisms are in a dissolved state in the form of ions - positively charged cations and adversely charged anions.
The concentration of cations and anions in the cell and in the environment surrounding it. The cage contains quite a lot of potassium and very little sodium. In extracellular medium, for example, in the blood plasma, in sea water, on the contrary, a lot of sodium and little potassium. The irritability of the cell depends on the ratio of the concentrations of Na +, K +, Ca2 +, Mg2 + ions.
The difference in the concentrations of ions on different sides of the membrane provides active transfer of substances through the membrane.
In the tissues of multicellular animals, CA2 + is part of the intercellular substance that provides cell closure and their ordered location.
Chemical composition of cells
From the concentration of salts, osmotic pressure in the cell and its buffer properties depend.
Bufferpost Called the ability of the cell to maintain a weakly alkaline reaction of its contents at a constant level.
There are two buffer systems:
1) phosphate buffer system - phosphoric acid anions support the pH of the intracellular medium at 6.9
2) Bicarbonate buffer system - angular anions support the pH of the extracellular medium at 7.4.
Consider the equations of reactions occurring in buffer solutions.
If the cage increases the concentrationN +. , then the joining of the hydrogen cation to the carbonate anion is:
With an increase in the concentration of hydroxide anions, they are binding to:
N + ON- + H2O.
So carbonate anion can maintain a permanent environment.
Osmotic Called phenomena occurring in a system consisting of two solutions separated by a semi-permeable membrane.
In the vegetable cell, the role of semi-permeable films is performed by borderline layers of cytoplasm: plasmalama and tonoplast.
Plasmamemma - the outer membrane of the cytoplasm, adjacent to the cell shell. Tonoplast - the inner membrane of the cytoplasm, surrounding the vacuol. Vacuoles are cavities in the cytoplasm filled with cellular juice with an aqueous solution of carbohydrates, organic acids, salts, low molecular weight proteins, pigments.
The concentration of substances in cellular juice and in the external environment (in soil, water bodies) is not usually the same. If the intracellular concentration of substances is higher than in an external environment, water from the medium will flow into the cell, more precisely in the vacuol, with a greater speed than in the opposite direction. With an increase in the volume of the cell juice, due to the flow into the water cell, its pressure on the cytoplasm increases, tightly adjacent to the shell. With full saturation of the cell, it has a maximum volume.
The state of the inner voltage of the cell due to the high content of water and the developing pressure of the cell content onto its shell is called the Turgor Turgor ensures the preservation of the form by the form by the form (for example, leaves, non-hereate stems) and positions in space, as well as resistance to their action of mechanical factors. With a loss of water, a decrease in the turgora and withering is connected.
If the cell is in a hypertonic solution, the concentration of which is larger than the concentration of the cell juice, the diffusion rate of water from the cell juice will exceed the diffusion rate of water diffusion into the cell from the surrounding solution.
Due to the outlet of water from the cell, the volume of cell juice is reduced, the turgor decreases. Reducing the volume of cell vacuole is accompanied by a cytoplasm separation from the shell - occurs plasmolysis.
During the plasmolysis, the form of plasmolyzed protoplast is changing. Initially, the protoplast is lagging behind the cell wall in separate places, most often in the corners. Plasmolysis of such a form are called corner
The protoplast continues to lag behind the cell walls, while maintaining communication with them in separate places, the surface of the protoplast between these points has a concave form.
At this stage, plasmolysis is called concave gradually the protoplast breaks away from the cell walls over the entire surface and takes a rounded shape. Such plasmolysis is called convex
If plasmolyzed cell is placed in a hypotonic solution, the concentration of which is less than the concentration of cell juice, water from the surrounding solution will enter the vacuole inside. As a result of an increase in the volume of vacuole, the pressure of the cell juice on the cytoplasm will increase, which begins to approach the cell walls until the initial position is taken - it will occur deplasmolysis
Task number 3.
After reading the proposed text, respond to the following questions.
1) Determination of bufferiness
2) The buffer properties of the cell depend on the concentration of anions
3) the role of bufferiness in the cell
4) Equation of reactions occurring in a bicarbonate buffer system (on a magnetic board)
5) definition of osmosis (give examples)
6) the definition of plasmolysis and deplasmolysis slides
In the cell there are about 70 chemical elements of the Periodic System D. I. Mendeleev, however, the content of these elements differs significantly from their concentrations in the environment, which proves the unity of the organic world.
Chemical elements available in the cell are divided into three large groups: macroelements, mesoelements (oligo elements) and trace elements.
These include carbon, oxygen, hydrogen and nitrogen included in the main organic substances. Meso elements are sulfur, phosphorus, potassium, calcium, sodium, iron, magnesium, chlorine components of about 1, 9% of the cell mass.
Sulfur and phosphorus are the components of the most important organic compounds. Chemical elements whose concentration in a cell is about 0, 1% belongs to trace elements. This is zinc, iodine, copper, manganese, fluorine, cobalt, etc.
Cell substances are divided into inorganic and organic.
Inorganic substances include water and mineral salts.
Due to its physico-chemical properties, the water in the cell is a solvent, a medium for the flow of reactions, the starting material and the product of chemical reactions, performs transport and thermostat functions, gives the cell an elasticity, provides a plant cell prop.
Mineral salts in the cell can be in dissolved or not dissolved states.
Saluble salts dissociate on ions. The most important cations are potassium and sodium, facilitating the transfer of substances through the membrane and participating in the occurrence and conducting a nervous impulse; Calcium, which takes part in the processes of reducing muscle fibers and blood coagulation, magnesium, which is part of chlorophyll, and iron, which is part of a series of proteins, including hemoglobin. Zinc is part of the pancreatic hormone molecule - insulin, copper is required for photosynthesis and respiration processes.
The most important anions are phosphate anion, which is part of ATP and nucleic acids, and the residue of coalic acid, softening the oscillations of the pH of the medium.
The lack of calcium and phosphorus leads to rickets, the lack of iron - to anemia.
Organic cells are represented by carbohydrates, lipids, proteins, nucleic acids, ATP, vitamins and hormones.
The composition of carbohydrates includes mainly three chemical elements: carbon, oxygen and hydrogen.
Their general formula Cm (H20) N. Distinguish simple and complex carbohydrates. Simple carbohydrates (monosaccharides) contain a single sugar molecule. They are classified by the number of carbon atoms, for example, pentoses (C5) and hexoses (C6). Penosas include robose and deoxyribosis. Ribose is part of RNA and ATP. Deoxyribosis is a component of DNA. Hxosis is glucose, fructose, galactose, etc.
They take an active part in the metabolism in the cell and are part of complex carbohydrates - oligosaccharides and polysaccharides. Oligosaccharides (disaccharides) include sucrose (glucose + fructose), lactose or milk sugar (glucose + galactose), etc.
Examples of polysaccharides are starch, glycogen, cellulose and chitin.
Carbohydrates are performed in a plastic (construction), energy (energy value of splitting 1 g of carbohydrates - 17, 6 kJ), stocking and reference function. Carbohydrates can also be part of complex lipids and proteins.
Lipids are a group of hydrophobic substances.
These include fats, wax steroids, phospholipids, etc.
The structure of the fat molecule
Fat is the ester of the trochaty alcohol of glycerin and the highest organic (fat) acids. In the fat molecule, the hydrophilic part can be distinguished - the head (glycerol residue) and the hydrophobic part - "tailings" (residues of fatty acids), therefore, in water, the fat molecule is oriented strictly in a certain way: the hydrophilic part is directed to water, and the hydrophobic - from it.
Lipids are performed in a plastic (construction), energy (energy value of splitting 1 g of fat - 38, 9 kJ), stocking, protective (amortization) and regulatory (steroid hormones) functions.
Proteins are biopolymers whose monomers are amino acids.
Amino acids contain amino group, carboxyl group and radical. Amino acids differ only by radicals. The protein includes 20 major amino acids. Amino acids are connected to each other with the formation of peptide communications.
The chain of more than 20 amino acids is called a polypeptide or protein. Proteins form four main structures: primary, secondary, tertiary and quaternary.
The primary structure is a sequence of amino acids connected by peptide bond.
The secondary structure is a spiral, or a folded structure held by hydrogen bonds between atoms of oxygen and hydrogen of peptide groups of different turns of a spiral or folds.
The tertiary structure (globule) is held by hydrophobic, hydrogen, disulfide and other connections.
Tertiary protein structure
The tertiary structure is characteristic of most organism proteins, for example, moglobin muscles.
Quaternary protein structure.
The quaternary structure is the most complex formed by several polypeptide chains, connected mainly by the same connections as in tertiary.
The quaternary structure is characteristic of hemoglobin, chlorophyll, etc.
Proteins can be simple and complex. Simple proteins consist only of amino acids, while complex proteins (lipoproteins, chromoproteins, glycoproteins, nucleoproteins, etc.) contain a protein and non-peculiar part.
For example, the hemoglobin in addition to four polypeptide chains of Globin protein enters a non-leakage part - gem, in the center of which is an iron ion that gives the hemoglobin of a red color.
Functional activity of proteins depends on environmental conditions.
The loss of the protein molecule of its structure up to primary is called denaturation. The reverse process of restoring secondary and higher structures is renaturation. Complete destruction of the protein molecule is called destruction.
Proteins are performed in a cell a number of functions: plastic (construction), catalytic (enzymatic), energy (energy value of splitting 1 g of protein - 17, 6 kJ), signal (receptor), contractile (motor), transport, protective, regulatory, stocking.
Nucleic acids are biopolymers whose monomers are nucleotides.
The composition of the nucleotide includes a nitrogen base, the residue of sugar-pentoses and the residue of orthophosphoric acid. Two types of nucleic acids are isolated: ribonucleic (RNA) and deoxyry-bonuclein (DNA).
DNA includes four types of nucleotides: adenine (A), Timin (T), Guanine (g) and cytosin (C). The composition of these nucleotides includes sugar de zoxiribosis. For DNA, Chargaff rules are installed:
1) the number of adenyl nucleotides in DNA is equal to the amount of thymidyl (A \u003d T);
2) the number of guanilla nucleotides in DNA is equal to the amount of cytidyl (r \u003d c);
3) The sum of adenyl and guanilla nucleotides is equal to the sum of thymidyl and cytidyl (A + G \u003d T + C).
The structure of DNA was opened by F.
Creek and D. Watson (Nobel Prize in Physiology and Medicine 1962). DNA molecule is a two-chain helix.
Cell and its chemical composition
Nucleotides are connected to each other through the remains of phosphoric acid, forming phosphodiester communication, while nitrogenous bases are directed inside. The distance between nucleotides in the chain is 0, 34 nm.
Nucleotides of different chains are combined with each other by hydrogen bonds on the principle of complementarity: adenine is connected to the tyamic two hydrogen bonds (A \u003d T), and the guanine with a cytosine is three (g \u003d c).
The structure of nucleotide
The most important property of DNA is the ability to replicate (self-deed).
The main function of DNA is the storage and transfer of hereditary information.
It is concentrated in the kernel, mitochondria and plastids.
The composition of RNA also includes four nucleotides: adenine (a), URA-Cyl (y), guanine (g) and cytosine (C). The balance of sugar-pentoses in it is represented by Ribose.
RNA is basically single-stranded molecules. Three types of RNA are distinguished: information (and-RNA), transport (T-RNA) and ribosomal (P-RNA).
TRNA structure
All of them take an active part in the process of implementing hereditary information, which with DNA is rewritten to and-RNA, and on the latter the synthesis of protein is already carried out, T-RNA in the protein synthesis process brings amino acids to ribosomes, p-RNA is part of the ribosoma themselves.
Chemical composition of living cell
The drawing includes different chemical compounds. Some of them are inorganic - meet in inanimate nature. However, the cells are most characteristic of organic compounds whose molecules have a very complex structure.
Inorganic cell compounds. Water and salts are inorganic compounds. Most of all in water cells. It is necessary for all life processes.
Water is a good solvent. In aqueous solution, chemical interaction of various substances occurs. In the dissolved state, nutrients from the intercellular substance penetrate the cell through the membrane. Water also helps to remove substances from the cell, which are formed into the results of reactions in it.
The most important for the processes of vital cells of the salt to, Na, Ca, Mg, etc.
Organic cell compounds. The main role in the implementation of the cell function belongs to organic compounds. Among them, proteins, fats, carbohydrates and nucleic acids have the greatest importance.
Proteins are the main and most complex substances of any live cell.
In size, the protein molecule is hundreds and thousands of times greater than the molecules of inorganic connections. No proteins there is no life. Some proteins accelerate chemical reactions, performing the role of catalysts. Such proteins are called enzymes.
Fats and carbohydrates have a less complex structure.
They are a building material of the cell and serve as sources of energy for the processes of the body's vital activity.
Nucleic acids are formed in the cell core. Hence the name of their name (lat. Nuclease - core). Entering the chromosome, nucleic acids are involved in the storage and transfer of hereditary properties of the cell. Nucleic acids provide protein formation.
Life properties of the cell. The main life property of the cell is metabolism.
Nutrients and oxygen are constantly coming from the intercellular substance in the cells and decay products are distinguished. Substances that entered the cell are involved in biosynthesis processes. Biosynthesis is the formation of proteins, fats, carbohydrates and their compounds from simpler substances. In the process of biosynthesis, substances are formed peculiar to certain organism cells.
For example, proteins that ensure their abbreviation are synthesized in muscle cells.
Simultaneously with biosynthesis in cells, the decay of organic compounds occurs. As a result of the decay, substances are formed by a simpler structure. Most of the decay reaction comes with the participation of oxygen and the release of energy.
Chemical organization cells
This energy is spent on the life processes flowing into the cell. The processes of biosynthesis and decay constitute the metabolism that is accompanied by the transformation of energy.
Cells are characteristic of growth and reproduction. Human body cells multiply dividing in half. Each of the resulting subsidiaries grows and reaches the size of the maternal. New cells perform the function of the maternal cell.
The life expectancy of cells is different: from several hours to decades.
Live cells are able to respond to physical and chemical changes in their environment. This property of cells is called excitability. In this case, from the state of resting the cells go into working condition - excitation. When exciting in cells, the rate of biosynthesis and decay of substances, oxygen consumption, temperature changes. In the excited state, different cells are performed by the functions of them.
Irony cells form and distinguish substances, muscle - reduced, a weak electrical signal occurs in nerve cells - a nervous impulse, which can spread through cell membranes.
Internal environment of the body.
Most body cells are not associated with the external environment. Their vital activity is provided by an inner medium, which is 3 types of liquids: intercellular (tissue) liquid with which cells directly come into contact, blood and lymph. The inner medium provides cells with substances necessary for their livelihoods, and decay products are removed through it.
The internal environment of the body has the relative constancy of the composition and physicochemical properties. Only on this condition of the cell can function normally.
The metabolism, biosynthesis and decay of organic compounds, growth, reproduction, excitability - the main life properties of the cells.
The life properties of cells are provided by the relative constancy of the composition of the inner environment.
From the course of botany and zoology, you know that the body of plants and animals are built of cells. The human body also consists of cells. Thanks to the cellular structure of the body, its growth, reproduction, restoration of organs and tissues and other forms of activity are possible.
The shape and dimensions of the cells depend on the function being performed. The main device for studying the structure of the cell is a microscope. The light microscope allows you to consider the cell with an increase in about three thousand times; An electron microscope in which the electron flow is used instead of light, hundreds of thousands of times. Cytology is engaged in studying the structure and functions of cells (from Greek. "Cytos" - a cell).
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Cytoplasm- viscous semi-winged substance. The cytoplasm contains a number of the smallest cell structures - organoidswhich perform various functions. Consider the most important organides: mitochondria, network of tubuages, ribosomes, cellular center, core.
Mitochondria- Short thickened calfs with inner partitions. They produce a substance rich in the energy required for the processes occurring in the ATP cell. It is noted that the more active the cell works, the more mitochondria in it.
Network Channelspermeates the entire cytoplasm. On these channels, the substances movement occur and the connection between organides is established.
Ribosomes- Dense calves containing protein and ribonucleic acid. They are the place of formation of proteins.
Cell Centereducated by calves that are involved in cell division. They are located near the kernel.
Core- This is a taurus, which is a mandatory component of the cell. During cell division, the kernel structure changes. When cell division ends, the kernel returns to the previous state. There is a special substance in the core - chromatinfrom which filamental calves are formed before dividing the cell - chromosome.For cells, a constant number of chromosomes of a certain form is characterized. In human body cells, it is contained in 46 chromosomes, and in the genital cells of 23.
Chemical composition of the cell.The cells of the human body consist of a variety of chemical compounds of inorganic and organic nature. Inorganic cell substances include water and salts. Water is up to 80% of the mass of the cell. It dissolves substances involved in chemical reactions: tolerates nutrients, removes spent and harmful connections from the cell. Mineral salts - sodium chloride, potassium chloride, etc. - play an important role in the water distribution between the cells and the intercellular substance. Separate chemical elements, such as oxygen, hydrogen, nitrogen, sulfur, iron, magnesium, zinc, iodine, phosphorus, are involved in creating vital organic compounds. Organic compounds form up to 20-30% of the mass of each cell. Among organic compounds, carbohydrates, fats, proteins and nucleic acids have the greatest importance.
Carbohydratesconsist of carbon, hydrogen and oxygen. Carbohydrates include glucose, animal starch - glycogen. Many carbohydrates are well soluble in water and are the main sources of energy to implement all life processes. When decaying 1 g of carbohydrates is released 17.6 kJ of energy.
Fat.formed by the same chemical elements as carbohydrates. Fats are insoluble in water. They are part of cell membranes. Fats also serve as a spare energy source in the body. With full splitting 1 g of fat, 38.9 kJ of energy is exempt.Proteinsare the basic cell substances. Proteins are the most complex of organic substances that occur in the nature, although consisting of a relatively small number of chemical elements - carbon, hydrogen, oxygen, nitrogen, sulfur. Very often, the protein includes phosphorus. The protein molecule has large dimensions and is a chain consisting of dozens and hundreds of simpler compounds - 20 types of amino acids.
Proteins serve as the main building material. They are involved in the formation of cell membranes, kernels, cytoplasm, organoids. Many proteins perform the role of chemical reaction flow accelerators - enzymes.Biochemical processes can occur in a cell only in the presence of special enzymes that accelerate the chemical transformations of substances in hundreds of millions times.
Proteins have a variety of structure. Only in one cell there are up to 1000 different proteins.
With the breakdown of proteins in the body, approximately the same amount of energy is released as when the carbohydrate cleavage is 17.6 kJ for 1 g.
Nucleic acidsfood in the cell core. Their name is connected with this (from Lat. Nucleus - core). They consist of carbon, oxygen, hydrogen and nitrogen and phosphorus. Nucleic acids are two types - deoxyribonucleic (DNA) and ribonucleic (RNA). DNA are mainly in cell chromosomes. DNA determines the composition of cell proteins and the transfer of hereditary signs and properties from parents to the offspring. RNA functions are associated with the formation of proteins characteristic of this cell.
Major terms and concepts:
The cell is the main elementary unit of all living things, so it is inherent in all properties of living organisms: a highly ordered structure, energy obtaining from the outside and its use to perform work and maintain ordering, metabolism, active reaction to irritation, growth, development, reproduction, doubling and biological transmission information to descendants, regeneration (restoration of damaged structures), an environmental adaptation.
German scientist T. Svann in the middle of the XIX century created a cell theory, the main provisions of which indicated that all tissues and organs consist of cells; Cells of plants and animals are fundamentally similar to each other, they all occur equally; The activities of organisms are the amount of vital activity of individual cells. A great influence on the further development of cell theory and generally for the doctrine of the cell was provided by the Great German scientist R. Virchov. He not only brought together all numerous scattered facts, but also convincingly showed that cells are a constant structure and occur only by reproduction.
Cell theory in modern interpretation includes the following main provisions: the cell is a universal elementary unit of living; Cells of all organisms are fundamentally similar in their structure, functions and chemical composition; cells are multiplied only by dividing the source cell; Multicolve organisms are complex cellular ensembles forming holistic systems.
Thanks to modern methods, research was identified two main types of cells: more complexly organized, highly differentiated eukaryotic cells (plants, animals and some simplest, algae, mushrooms and lichens) and less difficult to organized prokaryotic cells (blue-green algae, actinomycetes, bacteria, spirochetes, mycoplasma, rickettsia, chlamydia).
Unlike the prokaryotic eukaryotic cell, has a kernel bounded by a double nuclear membrane, and a large number of membrane organelles.
ATTENTION!
The cell is the main structural and functional unit of living organisms that exercise growth, development, metabolism and energy storing, processing and implementing genetic information. From the point of view of morphology, the cell is a complex system of biopolymers separated from the external environment of the plasma membrane (plasmolm) and consisting of kernel and cytoplasm, in which orgella and inclusion (granules) are located.
What cells are there?
Cells are varied in their form, structure, chemical composition and nature of metabolism.
All cells are homologous, i.e. They have a number of common structural features, on which the implementation of basic functions depends. Cells are inherent in the unity of the structure, metabolism (metabolism) and chemical composition.
At the same time, different cells have specific structures. This is due to the performance of special functions.
Cell structure
Ultramicroscopic structure of the cell:
1 - cytlemma (plasma membrane); 2 - Pinocytous bubbles; 3 - Centrosome Cell Center (cytocentre); 4 - hyaloplasm; 5 - endoplasmic network: a - membrane of a grainy network; b - ribosomes; 6 - the connection of the pericleary space with the cavities of the endoplasmic network; 7 - core; 8 - nuclear pores; 9 - non-thin (smooth) endoplasmic network; 10 - nuclei; 11 - internal net apparatus (Golgi complex); 12 - secretory vacuoles; 13 - Mitochondria; 14 - liposomes; 15 - three consecutive stages of phagocytosis; 16 - Communication of the cell shell (cytlemma) with the membranes of the endoplasmic network.
Chemical composition of cells
The cell includes more than 100 chemical elements, four of them account for about 98% of the mass, these are organogen: oxygen (65-75%), carbon (15-18%), hydrogen (8-10%) and nitrogen (1 , 5-3.0%). The remaining elements are divided into three groups: macroelements - their content in the body exceeds 0.01%); Microelements (0.00001-0.01%) and ultramic-elements (less than 0.00001).
Macroelements include sulfur, phosphorus, chlorine, potassium, sodium, magnesium, calcium.
To microelegen-there - iron, zinc, copper, iodine, fluorine, aluminum, copper, manganese, cobalt, etc.
To ultramicroilelements - selenium, vanadium, silicon, nickel, lithium, silver and up. Despite the very small content, trace elements and ultramic-elements play a very important role. They affect mainly on metabolism. Without them, the normal vital activity of each cell and the body as a whole is impossible.
The cell consists of inorganic and organic substances. Among the inorganic largest water. The relative amount of water in the cell ranges from 70 to 80%. Water is a universal solvent, it takes all biochemical reactions in the cell. With the participation of water, heat regulation is carried out. Substances dissolving in water (salts, bases, acids, proteins, carbohydrates, alcohols, etc.) are called hydrophilic. Hydrophobic substances (fats and leaf-like) do not dissolve in water. Other inorganic substances (salts, acids, bases, positive and negative ions are made up from 1.0 to 1.5%.
Among the organic substances are proteins (10-20%), fats, or lipids (1-5%), carbohydrates (0.2-2.0%), nucleic acids (1-2%). The content of low molecular weight substances does not exceed 0.5%.
The protein molecule is a polymer that consists of a large number of duplicate monomer units. The amino acid protein monomers (them 20) are interconnected by peptide bonds, forming a polypeptide chain (primary protein structure). It is twisted into the spiral, forming, in turn, the secondary structure of the protein. Due to the specific spatial orientation of the polypeptide chain, the tertiary structure of the protein occurs, which determines the specificity and biological activity of the protein molecule. Several tertiary structures, combining among themselves, form a quaternary structure.
Proteins perform essential functions. Enzymes - biological catalysts that increase the speed of chemical reactions in a cell of hundreds of thousands of millions of times are proteins. Proteins, entering all cellular structures, perform plastic (construction) function. Cell movements also carry out proteins. They provide transport substances into a cage, from the cell and inside the cell. Important is the protective function of proteins (antibodies). Proteins are one of the sources of energy. Vegetables are divided into monosaccharides and polysaccharides. The latter are built of monosaccharides, similar to amino acids, monomers. Among monosaccharides in the cell, glucose, fructose is most important (contains six carbon atoms) and pentosose (five carbon atoms). Pentoses are part of nucleic acids. Monosaccharides are well soluble in water. Polysaccharides are poorly dissolved in water (in animal glycogen cells, in vegetable - starch and cellulose. Carbohydrates are a source of energy, complex carbohydrates, connected to proteins (glycoproteins), fats (glycolipids), are involved in the formation of cell surfaces and cell interactions.
Lipid includes fats and leafy-like substances. Fat molecules are constructed from glycerol and fatty acids. The residential substances include cholesterol, some hormones, lecithin. Lipids, which are the main component of cell membranes, thereby perform the construction function. Lipids are essential energy sources. So, if at full oxidation of 1 g of protein or carbohydrates is released 17.6 kJ of energy, then with full oxidation of 1 g of fat - 38.9 kJ. Lipids carry out thermoregulation, protect organs (fat capsules).
DNA and RNA
Nucleic acids are polymer molecules formed by nucleotide monomers. The nucleotide consists of purine or pyrimidine base, sugar (pentoses) and phosphoric acid residue. In all cells there are two types of nucleic acids: deoxyribonulein (DNA) and ribonucleic (RNA), which differ in the composition of bases and sugars.
Spatial structure of nucleic acids:
(according to B. Alberts et al., Smy.). I - RNA; II - DNA; ribbons - sugar phosphate cozov; A, C, G, T, U - nitrogen bases, lattices between them are hydrogen bonds.
DNA molecule
The DNA molecule consists of two polynucleotide chains twisted one around the other in the form of a double helix. Nitrogenous bases of both chains are interconnected by complementary with hydrogen bonds. Adenine is connected only with thimine, and cytosin - with guanin (A - T, Mr.). The DNA recorded genetic information, which determines the specificity of proteins synthesized by the cell, i.e., the sequence of amino acids in the polypeptide chain. DNA transmits inheritance all cell properties. DNA is contained in the kernel and mitochondria.
RNA molecule
RNA molecule is formed by one polynucleotide chain. In cells there are three types of RNA. Information, or Messenger RNA TRNA (from Eng. Messenger - Intermediary), which transfers information about the nucleotide DNA sequence in the ribosomes (see below). Transport RNA (TRNA) that transfers amino acids in ribosomes. Ribosomal RNA (RRNA), which is involved in the formation of ribosomes. RNA is contained in the kernel, ribosomes, cytoplasm, mitochondria, chloroplasts.
The composition of nucleic acids.
Atlas: Anatomy and human physiology. Full practical manual Elena Yuryevna Zigalova
Chemical composition of cells
Chemical composition of cells
The cell includes more than 100 chemical elements, four of them account for about 98% of the mass, this organogen: oxygen (65-75%), carbon (15-18%), hydrogen (8-10%) and nitrogen (1.5-3.0%). The remaining elements are divided into three groups: macroelements - their content in the body exceeds 0.01%); Microelements (0.00001-0.01%) and ultramic-elements (less than 0.00001). Macroelements include sulfur, phosphorus, chlorine, potassium, sodium, magnesium, calcium. To trace elements - iron, zinc, copper, iodine, fluorine, aluminum, copper, manganese, cobalt, etc. To ultramic-elements - selenium, vanadium, silicon, nickel, lithium, silver and up. Despite the very small content, trace elements and ultramic-elements play a very important role. They affect mainly on metabolism. Without them, the normal vital activity of each cell and the body as a whole is impossible.
Fig. 1. The ultramicroscopic structure of the cell.1 - cytlemma (plasma membrane); 2 - Pinocytous bubbles; 3 - Centrosome Cell Center (cytocentre); 4 - hyaloplasm; 5 - endoplasmic network: a - membrane of a grainy network; b - ribosomes; 6 - the connection of the pericleary space with the cavities of the endoplasmic network; 7 - core; 8 - nuclear pores; 9 - non-thin (smooth) endoplasmic network; 10 - nuclei; 11 - internal net apparatus (Golgi complex); 12 - secretory vacuoles; 13 - Mitochondria; 14 - liposomes; 15 - three consecutive stages of phagocytosis; 16 - Communication of the cell shell (cytlemma) with membranes of the endoplasmic network
The cell consists of inorganic and organic substances. Among the inorganic largest water. The relative amount of water in the cell ranges from 70 to 80%. Water is a universal solvent, it takes all biochemical reactions in the cell. With the participation of water, heat regulation is carried out. Substances dissolving in water (salts, bases, acids, proteins, carbohydrates, alcohols, etc.) are called hydrophilic. Hydrophobic substances (fats and leaf-like) do not dissolve in water. Other inorganic substances (salts, acids, bases, positive and negative ions are made up from 1.0 to 1.5%.
Among the organic substances are proteins (10-20%), fats, or lipids (1-5%), carbohydrates (0.2-2.0%), nucleic acids (1-2%). The content of low molecular weight substances does not exceed 0.5%.
Molecule squirrelit is a polymer that consists of a large number of duplicate monomer units. The amino acid protein monomers (them 20) are interconnected by peptide bonds, forming a polypeptide chain (primary protein structure). It is twisted into the spiral, forming, in turn, the secondary structure of the protein. Due to the specific spatial orientation of the polypeptide chain, the tertiary structure of the protein occurs, which determines the specificity and biological activity of the protein molecule. Several tertiary structures, combining among themselves, form a quaternary structure.
Proteins perform essential functions. Enzymes- biological catalysts that increase the speed of chemical reactions in a cell of hundreds of thousands of millions times are proteins. Proteins, entering all cellular structures, perform plastic (construction) function. Cell movements also carry out proteins. They provide transport substances into a cage, from the cell and inside the cell. Important is the protective function of proteins (antibodies). Proteins are one of the sources of energy.
Carbohydratesdivided into monosaccharides and polysaccharides. The latter are built of monosaccharides, similar to amino acids, monomers. Among monosaccharides in the cell, glucose, fructose is most important (contains six carbon atoms) and pentosose (five carbon atoms). Pentoses are part of nucleic acids. Monosaccharides are well soluble in water. Polysaccharides are poorly dissolved in water (in animal glycogen cells, in vegetable - starch and cellulose. Carbohydrates are a source of energy, complex carbohydrates, connected to proteins (glycoproteins), fats (glycolipids), are involved in the formation of cell surfaces and cell interactions.
TO lipidambelieve fats and zero-like substances. Fat molecules are constructed from glycerol and fatty acids. The residential substances include cholesterol, some hormones, lecithin. Lipids, which are the main component of cell membranes (they are described below), thereby perform the construction function. Lipids are essential energy sources. So, if at full oxidation of 1 g of protein or carbohydrates is released 17.6 kJ of energy, then with full oxidation of 1 g of fat - 38.9 kJ. Lipids carry out thermoregulation, protect organs (fat capsules).
Nucleic acidsare polymer molecules formed by nucleotide monomers. The nucleotide consists of purine or pyrimidine base, sugar (pentoses) and phosphoric acid residue. In all cells there are two types of nucleic acids: deoxyribonulein (DNA) and ribonucleic (RNA), which differ in the composition of bases and sugars (Table 1, fig. 2.).
Fig. 2. The spatial structure of nucleic acids (according to B. Alberts et al., With ame.).I - RNA; II - DNA; ribbons - sugar phosphate cozov; A, c, g, t, u - nitrous bases, lattices between them - hydrogen bonds
The DNA molecule consists of two polynucleotide chains twisted one around the other in the form of a double helix. Nitrogenous bases of both chains are interconnected by complementary with hydrogen bonds. Adenine is connected only with thimine, and cytosin - with guanin(A - T, Mr.). The DNA recorded genetic information, which determines the specificity of proteins synthesized by the cell, i.e., the sequence of amino acids in the polypeptide chain. DNA transmits inheritance all cell properties. DNA is contained in the kernel and mitochondria.
RNA molecule is formed by one polynucleotide chain. In cells there are three types of RNA. Information, or Messenger RNA TRNA (from Eng. Messenger - Intermediary), which transfers information about the nucleotide DNA sequence in the ribosomes (see below).
Transport RNA (TRNA) that transfers amino acids in ribosomes. Ribosomal RNA (RRNA), which is involved in the formation of ribosomes. RNA is contained in the kernel, ribosomes, cytoplasm, mitochondria, chloroplasts.
Table 1
Composition of nucleic acids
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