Cell in chemistry. Composition and structure of an animal cell. Biological significance of water

Cell: chemical composition, structure, functions of organelles.

2.3 Chemical composition of the cell. Macro- and microelements. The relationship between the structure and functions of inorganic and organic substances (proteins, nucleic acids, carbohydrates, lipids, ATP) that make up the cell. The role of chemicals in the cell and human body.

Chemical elements that make up organisms.

When talking about the chemical composition of a cell, it should be remembered that we can talk about either chemical elements or chemical substances. Let's start with the chemical elements.

Living bodies contain the same chemical elements that form nonliving bodies. This speaks of the unity of living and nonliving matter. However, in living bodies the content of certain elements differs markedly.

Let's name the main elements and their meaning.

Carbon (C), hydrogen (H), oxygen ( O) and nitrogen ( N) constitute 98% of the mass of a living organism. The first three elements are part of all organic substances in the body. Nitrogen (hereinafter we mean elements) is part of proteins and nucleic acids.

Sulfur ( S) is part of some amino acids, and therefore part of proteins.

Iodine ( I) is necessary for normal operation thyroid gland, because is part of its hormones.

Phosphorus ( P) is important element ATP molecules and nucleic acids. And also, in the form of phosphates, it is part of bone tissue.

Iron is part of blood hemoglobin and is involved in gas transport.

Magnesium ( Mg) is the central atom in the chlorophyll molecule.

Calcium ( Ca) in the composition of insoluble compounds participates in the formation of supporting ( bone) and protective (mollusk shells) structures.

Potassium ( K) and sodium ( Na) in the form of ions are of great importance for maintaining the constancy of the composition of the internal environment, and also participate in the formation of nerve impulses in nerve cells.

Cell chemicals.

Carbohydrates .

The main function of carbohydrates is energy. In addition, they are part of the surface layer of the shell (glycocalyx ) animal cell and into the cell wall of bacteria, fungi and plants, performing a construction (structural) function.

Based on their structure, carbohydrates are divided into monosaccharides, disaccharides and polysaccharides. Among the monosaccharides, the most important are glucose (the main source of energy), ribose (part of RNA), and deoxyribose (part of DNA). The main polysaccharides are cellulose and starch in plants, glycogen and chitin in animals and fungi. All polysaccharides are polymers of regular structure, i.e. consist of only one type of monomer. For example, the monomer of starch, glycogen and cellulose is glucose.

Lipids.

Lipids also perform an energy function, and at the same time they provide twice as much energy per 1 g of substance as carbohydrates. But their construction function is especially important, because It is the double layer of lipids (or, to be precise, phospholipids) that is the basis of biological membranes. In addition, subcutaneous fatty tissue (in those who have it) performs the function of mechanical protection and thermoregulation.

Squirrels.

Squirrels – biopolymers of irregular structure, the monomers of which areamino acids . Proteins contain 20 types of amino acids, while the number of amino acids and the sequence of their connection in different protein molecules differs. As a result, proteins have a very diverse structure and, as a result, diverse properties and functions.

Levels of organization of a protein molecule (protein structure).

Below is a classic drawing depicting the different levels of organization of the hemoglobin molecule. Primary, secondary, tertiary and quaternary structures are indicated by numbers 1-4 respectively.

Functions of proteins.

Construction function proteins are one of the most important, since they are part of all cellular structures (membranes, organelles and cytoplasm). In fact, proteins are the main building material for the body. The growth and development of the body cannot occur normally without sufficient protein. That is why a growing body must necessarily receive proteins from food.

Enzymatic function proteins are no less important. Most chemical reactions occurring in a cell would not be possible without the participation of biological catalysts - enzymes. Almost all enzymes are proteins in nature. Each enzyme speeds up only one reaction (or one type of reaction). This expresses the specificity of enzymes. In addition, enzymes act in a rather narrow temperature range. An increase in temperature leads to their denaturation and loss of catalytic activity. An example of a typical enzyme is catalase, which breaks down hydrogen peroxide formed during the exchange into water and oxygen (2H 2 O 2 → 2 H 2 O + O 2 ). The effect of catalase can be observed when treating a bleeding wound with peroxide. The gas released is oxygen. You can also treat chopped potato tubers with peroxide. The same thing will happen.

Transport function proteins is responsible for the transport of various substances. Some proteins carry out transport on the scale of the whole organism. For example, hemoglobin in the blood carries oxygen and carbon dioxide throughout the body. Other proteins embedded in cell membranes provide transport of various substances into and out of the cell. A typical example is the potassium-sodium pump - a complex protein complex that pumps sodium out of the cell and pumps potassium into it.

Motor function proteins should not be confused with transport proteins. In this case we are talking about the movement of an organism or its individual parts relative to each other. An example is the proteins that make up muscle tissue: actin and myosin. The interaction of these proteins ensures muscle fiber contraction.

Protective function performed by many specific proteins. Antibodies produced by lymphocytes in the blood protect the body from pathogens. Special cellular proteins interferons provide antiviral protection. Plasma prothrombin is involved in blood clotting, protecting the body from blood loss.

Regulatory function performed by proteins that are hormones. A typical protein hormone, insulin regulates blood glucose levels. Another protein hormone is growth hormone.

Denaturation and renaturation of proteins.

The most important feature Most proteins are unstable in their structure under non-physiological conditions. When the temperature rises, changespHenvironment, exposure to solvents, etc. the bonds that support the spatial structure of the protein are destroyed. Happeningdenaturation , i.e. violation of the natural structure of the protein. The quaternary and tertiary structures are destroyed first. If the action unfavorable factor does not stop or intensify, then the secondary and even primary structure is destroyed. The destruction of the primary structure - the breaking of bonds between amino acids - means the end of the existence of the protein molecule. If the primary structure is preserved, then when favorable conditions the protein can restore its spatial structure, i.e. will happenrenaturation .

For example, when frying eggs under the influence high temperature The following changes occur with egg white: it was liquid and transparent, it became solid and opaque. However, after cooling, the protein does not become transparent and liquid again. In this case, renaturation does not occur, because During frying, the primary structure of the protein was destroyed.

Nucleic acids.

Nucleic acids , like proteins, are polymers of irregular structure. The monomers of nucleic acids arenucleotides . The schematic structure of a nucleotide is presented in Figure 2. As you can see, each nucleotide consists of three components: a nitrogenous base (polygon), a carbohydrate (pentagon) and a phosphoric acid residue (circle).

Comparative characteristics of DNA and RNA

Storage and transmission of hereditary information.

Regulation of cell vital processes.

Protein biosynthesis (i.e., essentially the process of implementing genetic information).

Types of RNA and their role in protein biosynthesis.

Messenger RNA (mRNA) - carries information about the primary structure of a protein from DNA to ribosomes.

Transfer RNA (tRNA) – delivers amino acids to ribosomes.

Ribosomal RNA (rRNA) - part of ribosomes, i.e. also participates in protein synthesis.

The structure of the DNA molecule.

The modern model of DNA structure was proposed by D. Watson and F. Crick. The DNA molecule consists of two chains of nucleotides, spirally twisted around each other. The nitrogenous bases are directed inside the molecule so that opposite the adenine of one chain there is always thymine of the other chain, and opposite guanine there is cytosine. Adenine - thymine and guanine - cytosine are complementary, and the principle of their arrangement in the DNA molecule is called the principle of complementarity. Two hydrogen bonds are formed between adenine and thymine, and three between cytosine and guanine. Thus, two chains of nucleotides in a DNA molecule are connected by many weak hydrogen bonds.

A consequence of the complementarity of A-T and G-C pairs is that the number of adenyl (A) nucleotides in DNA is always equal to the number of thymidyl (T). And in the same way, the number of guanyl (G) and cytidyl (C) nucleotides will also be the same. For example, if DNA contains 10% of nucleotides with adenine, then there will also be 10% of nucleotides with thymine, and 40% each with guanine and cytosine.

Content elements tested on the Unified State Exam:

2.4 Cell structure. The relationship between the structure and functions of the parts and organelles of a cell is the basis of its integrity.

Structure of a eukaryotic cell

1) Limits the contents of the cell, performs a protective function.

2) Provides selective transport.

3) Provides communication between cells in a multicellular organism.

Core

Has a double membrane. Inside ischromatin (DNA with proteins), as well as one or morenucleoli (site of assembly of ribosomal subunits). Communication with the cytoplasm occurs through nuclear pores.

1) Storage and transmission of hereditary information.

2) Control and management of cell life processes.

Cytoplasm

The internal environment of a cell, including the liquid part, organelles and inclusions. Interconnects all cellular structures

Mitochondria

They have a double membrane. The inner membrane forms folds -cristas , on which enzyme complexes that synthesize ATP are located. Have their own ribosomes and circular DNA

ATP synthesis

Endoplasmic reticulum (ER)

A network of tubules and cavities that permeate the entire cell. On the membranerough Ribosomes are located in the ER. On the membranesmooth There are no EPS.

Carries out the transport of substances by connecting various organiodes. Rough ER is also involved in the synthesis of proteins, and smooth ER is involved in the synthesis of carbohydrates and lipids.

Golgi apparatus

System of flat containers (tanks).

1) Accumulation, sorting, packaging and preparation of synthesized proteins for export from the cell.

2) Formation of lysosomes.

Lysosomes

Bubbles filled with a variety of enzymes.

Intracellular digestion.

Ribosomes

They consist of two subunits formed by proteins and rRNA.

Protein synthesis.

Cell center

In animals and lower plants it includes twocentrioles formed by nine triplets of microtubules.

Participates in cell division and formation of the cytoskeleton.

Movement organelles (cilia, flagella).

They are a cylinder whose wall consists of nine pairs of microtubules. Two more are located in the center.

Movement.

Plastids (found only in plants)

Chromoplasts (yellow - red) give color to flowers and fruits, which attracts pollinators and distributors of fruits and seeds. Leukoplasts (colorless) accumulate starch. Chloroplasts (green) carry out photosynthesis.

Chloroplasts

They have a double membrane. The inner membrane forms folds in the form of stacks of coins -grains . Separate "coin" -thylakoid . They have circular DNA and ribosomes.

Transport across the plasma membrane.

Passive transport occurs without energy expenditure (i.e. without ATP expenditure). The main type is diffusion. Through diffusion, oxygen enters the cell and carbon dioxide is released.

Active transport comes with energy costs. Main methods:

Transport using cellular pumps. Special protein complexes built into the membrane transport some ions into the cell and pump out others. For example, the potassium-sodium pump pumps out of the cellNa+ , but uploads K + . ATP is consumed for its work.

Phagocytosis – absorption of solid particles by the cell. The cell membrane forms protrusions that gradually close, and the absorbed particle ends up in the cytoplasm.

Pinocytosis is the absorption of liquid droplets by a cell. It occurs similarly to phagocytosis.

The chemical composition of a cell is closely related to the structural features and functioning of this elementary and functional unit of living things. As in morphological terms, the most common and universal for cells of representatives of all kingdoms is the chemical composition of the protoplast. The latter contains about 80% water, 10% organic matter and 1% salts. Among them, proteins, nucleic acids, lipids and carbohydrates play a leading role in the formation of a protoplast.

The composition of the chemical elements of the protoplast is extremely complex. It contains substances with both small molecular weight and substances with large molecules. 80% of the weight of the protoplast is made up of high molecular weight substances and only 30% is accounted for by low molecular weight compounds. At the same time, for each macromolecule there are hundreds, and for each large macromolecule there are thousands and tens of thousands of molecules.

The composition of any cell includes more than 60 elements of the periodic table.

Based on frequency of occurrence, elements can be divided into three groups:

Inorganic substances have low molecular weight and are found and synthesized both in living cells and in inanimate nature. In the cell, these substances are represented mainly by water and salts dissolved in it.

Water makes up about 70% of the cell. Due to its special property of molecular polarization, water plays a huge role in the life of a cell.

A water molecule consists of two hydrogen atoms and one oxygen atom.

The electrochemical structure of the molecule is such that oxygen has a slight excess of negative charge, and hydrogen atoms have a positive charge, that is, a water molecule has two parts that attract other water molecules with oppositely charged parts. This leads to an increase in the connection between molecules, which in turn determines the liquid state of aggregation at temperatures from 0 to 1000C, despite the relatively low molecular weight. At the same time, polarized water molecules provide better solubility of salts.

The role of water in the cell:

· Water is the medium of the cell; all biochemical reactions take place in it.

· Water performs a transport function.

· Water is a solvent for inorganic and some organic substances.

· Water itself participates in some reactions (for example, photolysis of water).

Salts are found in the cell, usually in dissolved form, that is, in the form of anions (negatively charged ions) and cations (positively charged ions).

The most important anions of the cell are hydroskid (OH -), carbonate (CO 3 2-), bicarbonate (CO 3 -), phosphate (PO 4 3-), hydrophosphate (HPO 4 -), dihydrogen phosphate (H 2 PO 4 -). The role of anions is enormous. Phosphate ensures the formation of high-energy bonds (chemical bonds with high energy). Carbonates provide buffering properties of the cytoplasm. Buffer capacity is the ability to maintain constant acidity of a solution.

The most important cations include proton (H +), potassium (K +), sodium (Na +). The proton participates in many biochemical reactions, and also determines such important characteristic cytoplasm as its acidity. Potassium and sodium ions provide this important property cell membrane as the conductivity of an electrical impulse.

The cell is the one elementary structure, which carries out all the main stages of biological metabolism and contains all the main chemical components of living matter. 80% of the weight of the protoplast consists of high-molecular substances - proteins, carbohydrates, lipids, nucleic acids, ATP. The organic substances of the cell are represented by various biochemical polymers, that is, molecules that consist of numerous repetitions of simpler, structurally similar sections (monomers).

2. Organic substances, their structure and role in the life of the cell.

The cell is the basic elementary unit of all living things, therefore it has all the properties of living organisms: a highly ordered structure, receiving energy from the outside and using it to perform work and maintain order, metabolism, an active response to irritations, growth, development, reproduction, duplication and transmission biological information descendants, regeneration (restoration of damaged structures), adaptation to the environment.

The German scientist T. Schwann in the middle of the 19th century created the cellular 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 arise in the same way; the activity of organisms is the sum of the vital activities of individual cells. Great influence on further development Cell theory and the theory of cells in general were influenced by the great German scientist R. Virchow. He not only brought together all the numerous disparate facts, but also convincingly showed that cells are a permanent structure and arise only through reproduction.

Cell theory in modern interpretation includes the following main provisions: the cell is a universal elementary unit of living things; the cells of all organisms are fundamentally similar in their structure, function and chemical composition; cells reproduce only by dividing the original cell; multicellular organisms are complex cellular assemblies that form integral systems.

Thanks to modern research methods, it was revealed two main cell types: more complexly organized, highly differentiated eukaryotic cells (plants, animals and some protozoa, algae, fungi and lichens) and less complexly organized prokaryotic cells (blue-green algae, actinomycetes, bacteria, spirochetes, mycoplasmas, rickettsia, chlamydia).

Unlike a prokaryotic cell, a eukaryotic cell has a nucleus bounded by a double nuclear membrane and a large number of membrane organelles.

ATTENTION!

The cell is the basic structural and functional unit of living organisms, carrying out growth, development, metabolism and energy, storing, processing and implementing genetic information. From a morphological point of view, a cell is a complex system of biopolymers, separated from the external environment by a plasma membrane (plasmolemma) and consisting of a nucleus and cytoplasm, in which organelles and inclusions (granules) are located.

What types of cells are there?

Cells are diverse in their shape, structure, chemical composition and nature of metabolism.

All cells are homologous, i.e. have a number of common structural features on which the performance of basic functions depends. Cells are characterized by unity of structure, metabolism (metabolism) and chemical composition.

At the same time, different cells also have specific structures. This is due to their performance of special functions.

Cell structure

Ultramicroscopic cell structure:

1 - cytolemma (plasma membrane); 2 - pinocytotic vesicles; 3 - centrosome, cell center (cytocenter); 4 - hyaloplasm; 5 - endoplasmic reticulum: a - membrane of the granular reticulum; b - ribosomes; 6 - connection of the perinuclear space with the cavities of the endoplasmic reticulum; 7 - core; 8 - nuclear pores; 9 - non-granular (smooth) endoplasmic reticulum; 10 - nucleolus; 11 - internal reticular apparatus (Golgi complex); 12 - secretory vacuoles; 13 - mitochondria; 14 - liposomes; 15 - three successive stages of phagocytosis; 16 - connection of the cell membrane (cytolemma) with the membranes of the endoplasmic reticulum.

Chemical composition of the cell

The cell contains more than 100 chemical elements, four of which account for about 98% of the mass; these are organogens: 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 ultramicroelements (less than 0.00001).

Macroelements include sulfur, phosphorus, chlorine, potassium, sodium, magnesium, calcium.

Microelements include iron, zinc, copper, iodine, fluorine, aluminum, copper, manganese, cobalt, etc.

Ultramicroelements include selenium, vanadium, silicon, nickel, lithium, silver and more. Despite their very low content, microelements and ultramicroelements play a very important role important role. They mainly affect metabolism. Without them, the normal functioning of each cell and the organism as a whole is impossible.

The cell consists of inorganic and organic substances. Among inorganic greatest number water. The relative amount of water in the cell is between 70 and 80%. Water is a universal solvent; all biochemical reactions in the cell take place in it. With the participation of water, thermoregulation is carried out. Substances that dissolve in water (salts, bases, acids, proteins, carbohydrates, alcohols, etc.) are called hydrophilic. Hydrophobic substances (fats and fat-like substances) do not dissolve in water. Other inorganic substances (salts, acids, bases, positive and negative ions) account for 1.0 to 1.5%.

Among organic substances, proteins (10–20%), fats or lipids (1–5%), carbohydrates (0.2–2.0%), and nucleic acids (1–2%) predominate. The content of low molecular weight substances does not exceed 0.5%.

A protein molecule is a polymer that consists of a large number of repeating units of monomers. Amino acid protein monomers (20 of them) are connected to each other by peptide bonds, forming a polypeptide chain (the primary structure of the protein). It twists into a 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 arises, which determines the specificity and biological activity of the protein molecule. Several tertiary structures combine with each other to form a quaternary structure.

Proteins perform essential functions. Enzymes - biological catalysts that increase the rate of chemical reactions in a cell hundreds of thousands of millions of times, are proteins. Proteins, being part of all cellular structures, perform a plastic (construction) function. Cell movements are also carried out by proteins. They provide transport of substances into the cell, out of the cell and within the cell. Important is protective function proteins (antibodies). Proteins are one of the sources of energy. Carbohydrates are divided into monosaccharides and polysaccharides. The latter are built from monosaccharides, which, like amino acids, are monomers. Among the monosaccharides in the cell, the most important are glucose, fructose (contains six carbon atoms) and pentose (five carbon atoms). Pentoses are part of nucleic acids. Monosaccharides are highly soluble in water. Polysaccharides are poorly soluble in water (glycogen in animal cells, starch and cellulose in plant cells). Carbohydrates are a source of energy; complex carbohydrates combined with proteins (glycoproteins), fats (glycolipids) are involved in the formation of cell surfaces and cell interactions.

Lipids include fats and fat-like substances. Fat molecules are made of glycerol and fatty acids. Fat-like substances include cholesterol, some hormones, and lecithin. Lipids, which are the main components of cell membranes, thereby perform a construction function. Lipids are the most important sources of energy. So, if with complete oxidation of 1 g of protein or carbohydrates 17.6 kJ of energy is released, then with complete oxidation of 1 g of fat - 38.9 kJ. Lipids carry out thermoregulation and protect organs (fat capsules).

DNA and RNA

Nucleic acids are polymer molecules formed by nucleotide monomers. A nucleotide consists of a purine or pyrimidine base, a sugar (pentose) and a phosphoric acid residue. In all cells, there are two types of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), which differ in the composition of bases and sugars.

Spatial structure of nucleic acids:

(according to B. Alberts et al., with modification). I - RNA; II - DNA; ribbons - sugar phosphate backbones; A, C, G, T, U are nitrogenous bases, the lattices between them are hydrogen bonds.

DNA molecule

A DNA molecule consists of two polynucleotide chains twisted around one another in the form of a double helix. The nitrogenous bases of both chains are connected to each other by complementary hydrogen bonds. Adenine combines only with thymine, and cytosine - with guanine (A - T, G - C). DNA contains genetic information that determines the specificity of the proteins synthesized by the cell, that is, the sequence of amino acids in the polypeptide chain. DNA transmits by inheritance all the properties of a cell. DNA is found in the nucleus and mitochondria.

RNA molecule

An RNA molecule is formed by one polynucleotide chain. There are three types of RNA in cells. Informational, or messenger RNA tRNA (from the English messenger - “intermediary”), which transfers information about the nucleotide sequence of DNA to ribosomes (see below). Transfer RNA (tRNA), which carries amino acids to ribosomes. Ribosomal RNA (rRNA), which is involved in the formation of ribosomes. RNA is found in the nucleus, ribosomes, cytoplasm, mitochondria, and chloroplasts.

Composition of nucleic acids.

A cell is the smallest structural and functional unit of living things. The cells of all living organisms, including humans, have a similar structure. The study of the structure, functions of cells, their interaction with each other is the basis for understanding such a complex organism as a person. The cell actively reacts to irritations, performs the functions of growth and reproduction; capable of self-reproduction and transmission of genetic information to descendants; to regeneration and adaptation to the environment.
Structure. In the adult human body there are about 200 types of cells, which differ in shape, structure, chemical composition and metabolism. Despite the great diversity, each cell of any organ represents an integral living system. The cell is divided into cytolemma, cytoplasm and nucleus (Fig. 5).
Cytolemma. Each cell has a shell - the cytolemma (cell membrane), which separates the contents of the cell from the external (extracellular) environment. The cytolemma not only limits the cell from the outside, but also ensures its direct connection with the external environment. The cytolemma performs protective, transport functions

1 - cytolemma (plasma membrane); 2 - pinocytotic vesicles; 3 - centrosome (cellular center, cytocenter); 4 - hyaloplasm;

- endoplasmic reticulum (a - endoplasmic reticulum membranes,
- ribosomes); 6 - core; 7 - connection of the perinuclear space with the cavities of the endoplasmic reticulum; 8 - nuclear pores; 9 - nucleolus; 10 - intracellular mesh apparatus (Golgi complex); 11 - secretory vacuoles; 12 - mitochondria; 13 - lysosomes; 14 - three successive stages of phagocytosis; 15 - cell membrane connection

(cytolemmas) with membranes of the endoplasmic reticulum

tions, perceives the influences of the external environment. Through the cytolemma, various molecules (particles) penetrate into the cell and exit the cell into its environment.
The cytolemma consists of lipid and protein molecules that are held together by complex intermolecular interactions. Thanks to them, the structural integrity of the membrane is maintained. The basis of the cytolemma is also made up of layers of lithium
polyprotein nature (lipids in combination with proteins). With a thickness of about 10 nm, the cytolemma is the thickest of the biological membranes. The cytolemma, a semi-permeable biological membrane, has three layers (Fig. 6, see color on). The outer and inner hydrophilic layers are formed by lipid molecules (lipid bilayer) and have a thickness of 5-7 nm. These layers are impermeable to most water-soluble molecules. Between the outer and inner layers there is an intermediate hydrophobic layer of lipid molecules. Membrane lipids include a large group of organic substances that are poorly soluble in water (hydrophobic) and highly soluble in organic solvents. Cell membranes contain phospholipids (glycerophosphatides), steroid lipids (cholesterol), etc.
Lipids make up about 50% of the mass of the plasma membrane.
Lipid molecules have hydrophilic (water loving) heads and hydrophobic (water fearing) ends. Lipid molecules are located in the cytolemma in such a way that the outer and inner layers (lipid bilayer) are formed by the heads of lipid molecules, and the intermediate layer is formed by their ends.
Membrane proteins do not form a continuous layer in the cytolemma. Proteins are located in lipid layers, plunging into them to different depths. Protein molecules have an irregular round shape and are formed from polypeptide helices. In this case, non-polar sections of proteins (not carrying charges), rich in non-polar amino acids (alanine, valine, glycine, leucine), are immersed in that part of the lipid membrane where the hydrophobic ends of lipid molecules are located. The polar parts of proteins (charge-bearing), also rich in amino acids, interact with the hydrophilic heads of lipid molecules.
In the plasma membrane, proteins make up almost half of its mass. There are transmembrane (integral), semi-integral and peripheral membrane proteins. Peripheral proteins are located on the surface of the membrane. Integral and semi-integral proteins are embedded in lipid layers. Molecules of integral proteins penetrate the entire lipid layer of the membrane, and semi-integral proteins are partially immersed in the membrane layers. Membrane proteins, according to them biological role, are divided into carrier proteins (transport proteins), enzyme proteins, and receptor proteins.
Membrane carbohydrates are represented by polysaccharide chains that are attached to membrane proteins and lipids. Such carbohydrates are called glycoproteins and glycolipids. The amount of carbohydrates in the cytolemma and other biological memes
branes is small. The mass of carbohydrates in the plasma membrane ranges from 2 to 10% of the membrane mass. Carbohydrates are located on outer surface cell membrane that is not in contact with the cytoplasm. Carbohydrates on the cell surface form a supra-membrane layer - the glycocalyx, which takes part in the processes of intercellular recognition. The thickness of the glycocalyx is 3-4 nm. Chemically, the glycocalyx is a glycoprotein complex, which includes various carbohydrates associated with proteins and lipids.
Functions of the plasma membrane. One of the most important functions of the cytolemma is transport. It ensures the entry of nutrients and energy into the cell, the removal of metabolic products from the cell and biologically active materials(secrets), regulates the passage of various ions into and out of the cell, and maintains the appropriate pH in the cell.
There are several mechanisms for substances entering and leaving the cell: diffusion, active transport, exo- or endocytosis.
Diffusion is the movement of molecules or ions from an area of high concentration to an area of lower concentration, i.e. along the concentration gradient. Due to diffusion, molecules of oxygen (02) and carbon dioxide (CO2) are transferred through membranes. Ions, molecules of glucose and amino acids, fatty acids diffuse through membranes slowly.
The direction of ion diffusion is determined by two factors: one of these factors is their concentration, and the other is electric charge. Ions typically move to a region of opposite charges and, repelled from a region of like charge, diffuse from a region of high concentration to a region of low concentration.
Active transport is the movement of molecules or ions across membranes using energy against a concentration gradient. Energy in the form of the breakdown of adenosine triphosphoric acid (ATP) is necessary to ensure the movement of substances from an environment with a lower concentration to an environment with a higher content. An example of active ion transport is the sodium-potassium pump (Na+, K+ pump). Na+ and ATP ions enter the membrane from the inside, and K+ ions from the outside. For every two K+ ions that enter the cell, three Na+ ions are removed from the cell. As a result, the contents of the cell become negatively charged in relation to the external environment. In this case, a potential difference arises between the two surfaces of the membrane.

The transfer of large molecules of nucleotides, amino acids, etc. across the membrane is carried out by membrane transport proteins. These are carrier proteins and channel-forming proteins. Carrier proteins combine with a molecule of the transported substance and transport it across the membrane. This process can be either passive or active. Channel-forming proteins form narrow pores filled with tissue fluid that penetrate the lipid bilayer. These channels have gates that open to a short time in response to specific processes that occur on the membrane.
The cytolemma is also involved in the absorption and release of various types of macromolecules and large particles by the cell. The process of passage of such particles through the membrane into the cell is called endocytosis, and the process of removing them from the cell is called exocytosis. During endocytosis, the plasma membrane forms protrusions or outgrowths, which, when laced, turn into vesicles. Particles or liquid trapped in the bubbles are transferred into the cell. There are two types of endocytosis - phagocytosis and pinocytosis. Phagocytosis (from the Greek phagos - devouring) is the absorption and transfer of large particles into the cell - for example, the remains of dead cells, bacteria). Pinocytosis (from the Greek pino - drink) is the absorption of liquid material, large-molecular compounds. Most particles or molecules taken up by the cell end up in the lysosomes, where the particles are digested by the cell. Exocytosis is the reverse process of endocytosis. During the process of exocytosis, the contents of transport or secreting vesicles are released into the extracellular space. In this case, the vesicles merge with the plasma membrane, and then open on its surface and release their contents into the extracellular environment.
The receptor functions of the cell membrane are carried out thanks to a large number of sensitive formations - receptors, present on the surface of the cytolemma. Receptors are capable of perceiving the effects of various chemical and physical stimuli. Receptors capable of recognizing stimuli are glycoproteins and glycolipids of the cytolemma. Receptors are distributed evenly over the entire cell surface or can be concentrated on any one part of the cell membrane. There are receptors that recognize hormones, mediators, antigens, and various proteins.
Intercellular connections are formed by the connection and closure of the cytolemma of adjacent cells. Intercellular connections ensure the transmission of chemical and electrical signals from one cell to another and are involved in relationships
cells. There are simple, dense, slit-like, synaptic intercellular connections. Simple connections are formed when the cytolemmas of two neighboring cells are simply in contact, adjacent to one another. In places of tight intercellular connections, the cytolemma of two cells is as close as possible, merging in places, forming, as it were, one membrane. At gap junctions (nexuses), there is a very narrow gap (2-3 nm) between the two cytolemmas. Synaptic connections (synapses) are characteristic of contacts of nerve cells with each other, when a signal (nerve impulse) can be transmitted from one nerve cell to another nerve cell in only one direction.
From a functional point of view, intercellular connections can be divided into three groups. These are locking connections, attachment and communication contacts. Gating junctions connect cells very tightly, making it impossible for even small molecules to pass through them. Attachment junctions mechanically link cells to neighboring cells or extracellular structures. Communication contacts between cells ensure the transmission of chemical and electrical signals. The main types of communication contacts are gap junctions and synapses.

From which chemical compounds(molecules) is the cytolemma built? How are the molecules of these compounds located in the membrane?
Where are membrane proteins located, what role do they play in the functions of the cytolemma?
Name and describe the types of transport of substances across the membrane.
How does active transport of substances across membranes differ from passive transport?
What is endocytosis and exocytosis? How are they different from each other?
What types of contacts (connections) of cells with each other do you know?

Cytoplasm. Inside the cell, under its cytolemma, there is cytoplasm, of which a homogeneous, semi-liquid part is isolated - the hyaloplasm and the organelles and inclusions contained in it.
Hyaloplasm (from the Greek hyalmos - transparent) is a complex colloidal system that fills the space between cellular organelles. Proteins are synthesized in the hyaloplasm and the energy reserve of the cell is located in it. Hyaloplasm unites various cell structures and provides
their chemical interaction, it forms a matrix - internal environment cells. On the outside, the hyaloplasm is covered with a cell membrane - the cytolemma. The composition of hyaloplasm includes water (up to 90%). Proteins necessary for the life and functioning of the cell are synthesized in the hyaloplasm. It contains energy reserves in the form of ATP molecules, fatty inclusions, and glycogen is deposited. The hyaloplasm contains general-purpose structures - organelles, which are present in all cells, and non-permanent formations - cytoplasmic inclusions. The organelles include granular and non-granular endoplasmic reticulum, internal mesh apparatus (Golgi complex), cell center (cytocenter), ribosomes, lysosomes. Inclusions include glycogen, proteins, fats, vitamins, pigment and other substances.
Organelles are cell structures that perform certain vital functions. important functions. There are membrane and non-membrane organelles. Membrane organelles are closed single or interconnected sections of the cytoplasm, separated from the hyaloplasm by membranes. Membranous organelles include the endoplasmic reticulum, internal reticular apparatus (Golgi complex), mitochondria, lysosomes, and peroxisomes.
The endoplasmic reticulum is formed by groups of cisterns, vesicles or tubes, the walls of which are a membrane 6-7 nm thick. The combination of these structures resembles a network. The endoplasmic reticulum is heterogeneous in structure. There are two types of endoplasmic reticulum - granular and non-granular (smooth).
The granular endoplasmic reticulum has many small round bodies - ribosomes - on the tube membranes. The membranes of the non-granular endoplasmic reticulum do not have ribosomes on their surface. The main function of the granular endoplasmic reticulum is participation in protein synthesis. The synthesis of lipids and polysaccharides occurs on the membranes of the non-granular endoplasmic reticulum.
The internal reticular apparatus (Golgi complex) is usually located near the cell nucleus. It consists of flattened tanks surrounded by a membrane. There are many small bubbles near the groups of tanks. The Golgi complex is involved in the accumulation of products synthesized in the endoplasmic reticulum and the removal of the resulting substances outside the cell. In addition, the Golgi complex ensures the formation of cellular lysosomes and peroximes.
Lysosomes are spherical membrane sacs (0.2-0.4 µm in diameter) filled with active chemicals.

biological substances, hydrolytic enzymes (hydrolases) that break down proteins, carbohydrates, fats and nucleic acids. Lysosomes are structures that carry out the intracellular digestion of biopolymers.
Peroxisomes are small, oval shape vacuoles 0.3-1.5 microns in size containing the enzyme catalase, which destroys hydrogen peroxide, which is formed as a result of oxidative deamination of amino acids.
Mitochondria are the energy stations of the cell. These are ovoid or spherical organelles with a diameter of about 0.5 microns and a length of 1 - 10 microns. Mitochondria, unlike other organelles, are limited by not one, but two membranes. The outer membrane has smooth contours and separates the mitochondria from the hyaloplasm. The inner membrane limits the contents of the mitochondrion, its fine-grained matrix, and forms numerous folds - ridges (cristae). The main function of mitochondria is the oxidation of organic compounds and the use of released energy for the synthesis of ATP. ATP synthesis occurs with the consumption of oxygen and occurs on the membranes of mitochondria and on the membranes of their cristae. The released energy is used to phosphorylate ADP (adenosine diphosphate) molecules and convert them into ATP.
Non-membrane organelles of the cell include the supporting apparatus of the cell, including microfilaments, microtubules and intermediate filaments, the cell center, and ribosomes.
The supporting apparatus, or cytoskeleton of the cell, provides the cell with the ability to maintain a certain shape and also carry out directed movements. The cytoskeleton is formed by protein filaments that penetrate the entire cytoplasm of the cell, filling the space between the nucleus and the cytolemma.
Microfilaments are also protein filaments 5-7 nm thick, located mainly in peripheral parts cytoplasm. Microfilaments include contractile proteins - actin, myosin, and tropomyosin. Thicker microfilaments, about 10 nm thick, are called intermediate filaments, or microfibrils. Intermediate filaments are arranged in bundles and have different compositions in different cells. IN muscle cells they are built from the protein demin, in epithelial cells - from keratin proteins, in nerve cells they are built from proteins that form neurofibrils.
Microtubules are hollow cylinders with a diameter of about 24 nm, consisting of the protein tubulin. They are the main structural and functional elements of the res
Niche and flagella, the basis of which are outgrowths of the cytoplasm. The main function of these organelles is support. Microtubules ensure the mobility of the cells themselves, as well as the movement of cilia and flagella, which are outgrowths of some cells (epithelium of the respiratory tract and other organs). Microtubules are part of the cell center.
The cellular center (cytocenter) is a collection of centrioles and the dense substance surrounding them - the centrosphere. The cell center is located near the cell nucleus. Centrioles have the shape of hollow cylinders with a diameter of about

25 microns and up to 0.5 microns long. The centriole walls are built of microtubules, which form 9 triplets (triple microtubules - 9x3).

Usually in a non-dividing cell there are two centrioles, which are located at an angle to one another and form a diplosome. When a cell prepares to divide, the centrioles double, so that the cell has four centrioles before division. Around the centrioles (diplosomas), consisting of microtubules, there is a centrosphere in the form of a structureless rim with radially oriented fibrils. Centrioles and centrosphere in dividing cells participate in the formation of the division spindle and are located at its poles.
Ribosomes are granules 15-35 nm in size. They contain proteins and RNA molecules in approximately equal weight ratios. Ribosomes are located freely in the cytoplasm or they are fixed on the membranes of the granular endoplasmic reticulum. Ribosomes are involved in the synthesis of protein molecules. They arrange amino acids into chains in strict accordance with the genetic information contained in DNA. Along with single ribosomes, cells contain groups of ribosomes that form polysomes, polyribosomes.
Cytoplasmic inclusions are optional components of the cell. They appear and disappear depending on the functional state of the cell. The main location of inclusions is the cytoplasm. Inclusions accumulate in it in the form of drops, granules, and crystals. There are trophic, secretory and pigment inclusions. Trophic inclusions include glycogen granules in liver cells, protein granules in eggs, drops of fat in fat cells, etc. They serve as reserves nutrients that the cell accumulates. Secretory inclusions are formed in glandular epithelial cells during their life. The inclusions contain biologically active substances accumulated in the form of secretory granules. Pigment inclusions
can be endogenous (if they are formed in the body itself - hemoglobin, lipofuscin, melanin) or exogenous (dyes, etc.) of origin.
Questions for repetition and self-control:

Name the main structural elements of a cell.
What properties does a cell have? elementary unit alive?
What are cell organelles? Tell us about the classification of organelles.
What organelles are involved in the synthesis and transport of substances in the cell?
Tell us about the structure and functional significance Golgi complex.
Describe the structure and functions of mitochondria.
Name the non-membrane cell organelles.
Define inclusions. Give examples.

The cell nucleus is an essential element of the cell. It contains genetic (hereditary) information and regulates protein synthesis. Genetic information is found in deoxyribonucleic acid (DNA) molecules. When a cell divides, this information is transferred in equal quantities to daughter cells. The nucleus has its own protein synthesis apparatus; the nucleus controls synthetic processes in the cytoplasm. Reproduced on DNA molecules different kinds ribonucleic acid: informational, transport, ribosomal.
The nucleus is usually spherical or ovoid in shape. Some cells (leukocytes, for example) have a bean-shaped, rod-shaped or segmented nucleus. The nucleus of a nondividing cell (interphase) consists of a shell, nucleoplasm (karyoplasm), chromatin and nucleolus.
The nuclear envelope (karyote) separates the contents of the nucleus from the cytoplasm of the cell and regulates the transport of substances between the nucleus and the cytoplasm. The karyoteca consists of outer and inner membranes separated by a narrow perinuclear space. The outer nuclear membrane is in direct contact with the cytoplasm of the cell, with the membranes of the endoplasmic reticulum cisterns. On the surface of the nuclear membrane facing the cytoplasm there are numerous ribosomes. The nuclear envelope has nuclear pores closed by a complex diaphragm formed by interconnected protein granules. Metabolism occurs through nuclear pores
between the nucleus and cytoplasm of the cell. Ribonucleic acid (RNA) molecules and ribosomal subunits leave the nucleus into the cytoplasm, and proteins and nucleotides enter the nucleus.
Under the nuclear envelope there is a homogeneous nucleoplasm (karyoplasm) and a nucleolus. In the nucleoplasm of the non-dividing nucleus, in its nuclear protein matrix, there are granules (clumps) of the so-called heterochromatin. Areas of looser chromatin located between granules are called euchromatin. Loose chromatin is called decondensed chromatin; synthetic processes occur most intensively in it. During cell division, chromatin compacts, condenses, and forms chromosomes.
The chromatin of a nondividing nucleus and the chromosomes of a dividing nucleus have the same chemical composition. Both chromatin and chromosomes consist of DNA molecules associated with RNA and proteins (histones and non-histones). Each DNA molecule consists of two long right-handed polynucleotide chains (double helix). Each nucleotide consists of a nitrogenous base, a sugar and a phosphoric acid residue. Moreover, the base is located inside the double helix, and the sugar-phosphate skeleton is located outside.
Hereditary information in DNA molecules is recorded in the linear sequence of the arrangement of its nucleotides. The elementary particle of heredity is the gene. A gene is a section of DNA that has a specific sequence of nucleotides responsible for the synthesis of one specific specific protein.
The DNA molecules in the chromosome of the dividing nucleus are packed compactly. Thus, one DNA molecule containing 1 million nucleotides in a linear arrangement has a length of 0.34 mm. The length of one human chromosome when stretched is about 5 cm. DNA molecules associated with histone proteins form nucleosomes, which are the structural units of chromatin. Nucleosomes look like beads with a diameter of 10 nm. Each nucleosome consists of histones, around which a section of DNA is twisted, including 146 nucleotide pairs. Between the nucleosomes there are linear sections of DNA consisting of 60 nucleotide pairs. Chromatin is represented by fibrils that form loops about 0.4 μm long, containing from 20,000 to 300,000 nucleotide pairs.
As a result of compaction (condensation) and twisting (supercoiling) of deoxyribonucleoproteins (DNPs) in the dividing nucleus, chromosomes are elongated rod-shaped formations with two arms divided so
called the constriction - the centromere. Depending on the location of the centromere and the length of the arms (legs), three types of chromosomes are distinguished: metacentric, which have approximately identical arms, submetacentric, in which the length of the arms (legs) is different, and acrocentric chromosomes, in which one arm is long and the other is long. very short, barely noticeable.
The surface of chromosomes is covered with various molecules, mainly ribonucleoprogeids (RNPs). Somatic cells have two copies of each chromosome. They are called homologous chromosomes; they are identical in length, shape, structure, and carry the same genes, which are located in the same way. The structural features, number and size of chromosomes are called a karyotype. A normal human karyotype includes 22 pairs of somatic chromosomes (autosomes) and one pair of sex chromosomes (XX or XY). Human somatic cells (diploid) have a double number of chromosomes - 46. Sex cells contain a haploid (single) set - 23 chromosomes. Therefore, in germ cells there is two times less DNA than in diploid somatic cells.
A nucleolus, one or more, is present in all non-dividing cells. It has the appearance of an intensely stained round body, the size of which is proportional to the intensity of protein synthesis. The nucleolus consists of an electron-dense nucleolonema (from the Greek neman - thread), in which filamentous (fibrillar) and granular parts are distinguished. The filamentous part consists of many intertwined strands of RNA about 5 nm thick. The granular (granular) part is formed by grains with a diameter of about 15 nm, which are particles of ribonucleoproteins - precursors of ribosomal subunits. Ribosomes are formed in the nucleolus.
Chemical composition of the cell. All cells of the human body are similar in chemical composition; they contain both inorganic and organic substances.
Inorganic substances. More than 80 chemical elements are found in the composition of the cell. Moreover, six of them - carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur - account for about 99% of the total mass of the cell. Chemical elements are found in the cell in the form of various compounds.
Water occupies the first place among the substances of the cell. It makes up about 70% of the cell mass. Most reactions occurring in a cell can only occur in an aqueous environment. Many substances enter the cell in aqueous solution. Metabolic products are also removed from the cell in an aqueous solution. Thanks to
In the presence of water, the cell retains its volume and elasticity. TO inorganic substances cells, in addition to water, contain salts. For the vital processes of the cell, the most important cations are K+, Na+, Mg2+, Ca2+, as well as the anions - H2PO~, C1, HCO. The concentration of cations and anions inside and outside the cell is different. So, inside the cell there is always a fairly high concentration of potassium ions and a low concentration of sodium ions. On the contrary, in the environment surrounding the cell, in the tissue fluid, there are fewer potassium ions and more sodium ions. In a living cell, these differences in the concentrations of potassium and sodium ions between the intracellular and extracellular environments remain constant.
Organic substances. Almost all cell molecules are carbon compounds. With four electrons in its outer shell, a carbon atom can form four strong covalent bonds with other atoms, creating large, complex molecules. Other atoms that are widely present in the cell and to which carbon atoms readily combine are hydrogen, nitrogen, and oxygen atoms. They, like carbon, are small in size and capable of forming very strong covalent bonds.
Most organic compounds form molecules large sizes, called macromolecules (Greek makros - large). Such molecules consist of repeating compounds similar in structure and interconnected - monomers (Greek monos - one). A macromolecule formed by monomers is called a polymer (Greek poly - many).
The bulk of the cytoplasm and nucleus of the cell consists of proteins. All proteins contain hydrogen, oxygen and nitrogen atoms. Many proteins also contain sulfur and phosphorus atoms. Each protein molecule consists of thousands of atoms. There are a huge number of different proteins built from amino acids.
Over 170 amino acids are found in the cells and tissues of animal and plant organisms. Each amino acid has a carboxyl group (COOH), which has acidic properties, and an amino group (-NH2), which has basic properties. The regions of molecules not occupied by carboxy and amino groups are called radicals (R). In the simplest case, the radical consists of a single hydrogen atom, but in more complex amino acids it can be a complex structure consisting of many carbon atoms.
The most important amino acids include alanine, glutamic and aspartic acids, proline, leucine, cysteine. Connections of amino acids with each other are called peptide bonds. The resulting amino acid compounds are called peptides. A peptide made of two amino acids is called a dipeptide.
from three amino acids - a tripeptide, from many amino acids - a polypeptide. Most proteins contain 300-500 amino acids. There are also larger protein molecules consisting of 1500 or more amino acids. Proteins differ in composition, number and order of alternation of amino acids in the polypeptide chain. It is the sequence of alternation of amino acids that is of paramount importance in the existing diversity of proteins. Many protein molecules are long and have high molecular weight. Thus, the molecular weight of insulin is 5700, hemoglobin is 65,000, and the molecular weight of water is only 18.
The polypeptide chains of proteins are not always elongated. On the contrary, they can twist, bend or fold in a variety of ways. Variety of physical and chemical properties proteins provide the characteristics of the functions they perform: construction, motor, transport, protective, energy.
Carbohydrates contained in cells are also organic substances. Carbohydrates contain carbon, oxygen and hydrogen atoms. There are simple and complex carbohydrates. Simple carbohydrates are called monosaccharides. Complex carbohydrates are polymers in which monosaccharides play the role of monomers. A disaccharide is formed from two monomers, a trisaccharide from three, and a polysaccharide from many. All monosaccharides are colorless substances, highly soluble in water. The most common monosaccharides in animal cells are glucose, ribose, and deoxyribose.
Glucose is the primary source of energy for the cell. When split, it turns into carbon monoxide and water (C02 + + H20). During this reaction, energy is released (when 1 g of glucose is broken down, 17.6 kJ of energy is released). Ribose and deoxyribose are components of nucleic acids and ATP.
Lipids are made up of the same chemical elements as carbohydrates - carbon, hydrogen and oxygen. Lipids do not dissolve in water. The most common and well-known lipids are ego fats, which are a source of energy. When fats are broken down, twice as much energy is released as when carbohydrates are broken down. Lipids are hydrophobic and therefore are part of cell membranes.
Cells contain nucleic acids - DNA and RNA. The name "nucleic acids" comes from the Latin word "nucleus", those. the core where they were first discovered. Nucleic acids are nucleotides connected in series to each other. Nucleotide is a chemical
a compound consisting of one sugar molecule and one organic base molecule. Organic bases, when interacting with acids, can form salts.
Each DNA molecule consists of two strands, spirally twisted around one another. Each chain is a polymer whose monomers are nucleotides. Each nucleotide contains one of four bases - adenine, cytosine, guanine or thymine. When a double helix is formed, the nitrogenous bases of one chain “join” with the nitrogenous bases of the other. The bases come so close to each other that hydrogen bonds occur between them. There is an important pattern in the arrangement of connecting nucleotides, namely: against adenine (A) of one chain there is always thymine (T) of another chain, and against guanine (G) of one chain - cytosine (C). In each of these combinations, both nucleotides seem to complement each other. The word "supplement" Latin stands for "complement". Therefore, it is customary to say that guanine is complementary to cytosine, and thymine is complementary to adenine. Thus, if the order of nucleotides in one chain is known, then the complementary principle immediately determines the order of nucleotides in the other chain.
In polynucleotide chains of DNA, every three consecutive nucleotides form a triplet (a set of three components). Each triplet is not just a random group of three nucleotides, but a codagen (in Greek, codagen is the region that forms a codon). Each codon encodes (encrypts) only one amino acid. The sequence of codegens contains (recorded) primary information about the sequence of amino acids in proteins. DNA has a unique property - the ability to duplicate, which no other known molecule has.
The RNA molecule is also a polymer. Its monomers are nucleotides. RNA is a single stranded molecule. This molecule is built in the same way as one of the DNA strands. Ribonucleic acid, like DNA, contains triplets - combinations of three nucleotides, or information units. Each triplet controls the inclusion of a very specific amino acid in the protein. The order of alternation of amino acids being built is determined by the sequence of RNA triplets. The information contained in RNA is the information obtained from DNA. The transfer of information is based on the already known principle of complementarity.

Each DNA triplet is paired with a complementary RNA triplet. An RNA triplet is called a codon. The codon sequence contains information about the sequence of amino acids in proteins. This information is copied from the information recorded in the codogen sequence in the DNA molecule.
Unlike DNA, the content of which in the cells of specific organisms is relatively constant, the content of RNA fluctuates and depends on synthetic processes in the cell.
Based on their functions, there are several types of ribonucleic acid. Transfer RNA (tRNA) is mainly found in the cytoplasm of the cell. Ribosomal RNA (rRNA) makes up an essential part of the structure of ribosomes. Messenger RNA (mRNA), or matrix RNA (mRNA), is found in the cell nucleus and cytoplasm and carries information about protein structure from DNA to the site of protein synthesis in ribosomes. All types of RNA are synthesized on DNA, which serves as a kind of template.
Adenosine triphosphoric acid (ATP) is found in every cell. According to its chemical structure, ATP is classified as a nucleotide. It and each nucleotide contain one molecule of organic base (adenine), one molecule of carbohydrate (ribose) and three molecules of phosphoric acid. ATP differs significantly from ordinary nucleotides by the presence of not one, but three molecules of phosphoric acid.
Adenosine monophosphoric acid (AMP) is part of all RNA. When two more molecules of phosphoric acid (H3P04) are added, it turns into ATP and becomes a source of energy. It is the connection between the second and third

More, others - less.

At the atomic level, there are no differences between the organic and inorganic world of living nature: living organisms consist of the same atoms as bodies of inanimate nature. However, the ratio of different chemical elements in living organisms and in the earth's crust varies greatly. In addition, living organisms may differ from their environment in the isotopic composition of chemical elements.

Conventionally, all elements of the cell can be divided into three groups.

Macronutrients

Zinc- is part of the enzymes involved in alcoholic fermentation and insulin

Copper- is part of the oxidative enzymes involved in the synthesis of cytochromes.

Selenium- participates in the regulatory processes of the body.

Ultramicroelements

Ultramicroelements make up less than 0.0000001% in the organisms of living beings, these include gold, silver have a bactericidal effect, suppress the reabsorption of water in the renal tubules, affecting enzymes. Ultramicroelements also include platinum and cesium. Some people also include selenium in this group; with its deficiency, they develop cancer. The functions of ultramicroelements are still poorly understood.