A cell is an elementary unit of a living thing that has all the characteristics of an organism: the ability to reproduce, grow, exchange substances and energy with the environment, irritability, and the constancy of chemical composition.
Macronutrients - elements, the amount of which in the cell is up to 0.001% of body weight. Examples are oxygen, carbon, nitrogen, phosphorus, hydrogen, sulfur, iron, sodium, calcium, etc.
Trace elements - elements, the amount of which in the cell is from 0.001% to 0.000001% of body weight. Examples are boron, copper, cobalt, zinc, iodine, etc.
Ultramicroelements are elements whose content in the cell does not exceed 0.000001% of body weight. Examples are gold, mercury, cesium, selenium, etc.
2. Make a diagram of "Cell Substances".
3. What is he talking about scientific fact similarities of the elementary chemical composition of animate and inanimate nature?
This indicates the commonality of animate and inanimate nature.
inorganic substances. The role of water and minerals in the life of the cell.
1. Give definitions of concepts.
Inorganic substances are water, mineral salts, acids, anions and cations present in both living and non-living organisms.
Water is one of the most common inorganic substances in nature, the molecule of which consists of two hydrogen atoms and one oxygen atom.
2. Draw a diagram of the structure of water.
3. What features of the structure of water molecules give it unique properties without which life is impossible?
The structure of the water molecule is formed by two hydrogen atoms and one oxygen atom, which form a dipole, that is, water has two polarities "+" and "-". This contributes to its permeability through the membrane walls, the ability to dissolve chemical substances. In addition, water dipoles are hydrogen bonded to each other, which ensures its ability to be in various states of aggregation, and also - to dissolve or not to dissolve various substances.
4. Fill in the table "The role of water and minerals in the cell."
5. What is the meaning of relative constancy internal environment cells in ensuring the processes of its vital activity?
The constancy of the internal environment of the cell is called homeostasis. Violation of homeostasis leads to damage to the cell or to its death, plastic metabolism and energy metabolism constantly occur in the cell, these are two components of metabolism, and violation of this process leads to damage or death of the whole organism.
6. What is the purpose of the buffer systems of living organisms and what is the principle of their functioning?
Buffer systems maintain a certain pH value (acidity index) of the medium in biological fluids. The principle of operation is that the pH of the medium depends on the concentration of protons in this medium (H+). The buffer system is capable of absorbing or donating protons, depending on their entry into the environment from outside or, on the contrary, removal from the environment, while the pH will not change. The presence of buffer systems is necessary in a living organism, since pH can change greatly due to changes in environmental conditions, and most enzymes work only at a certain pH value.
Examples of buffer systems:
carbonate-hydrocarbonate (mixture of Na2CO3 and NaHCO3)
phosphate (a mixture of K2HPO4 and KH2PO4).
organic matter. The role of carbohydrates, lipids and proteins in the life of the cell.
1. Give definitions of concepts.
Organic substances are substances that necessarily include carbon; they are part of living organisms and are formed only with their participation.
Proteins are high-molecular organic substances consisting of alpha-amino acids connected in a chain by a peptide bond.
Lipids are a broad group of natural organic compounds, including fats and fat-like substances. Simple lipid molecules consist of alcohol and fatty acids, complex lipids consist of alcohol, high molecular weight fatty acids and other components.
Carbohydrates are organic substances that contain carbonyl and several hydroxyl groups and are otherwise called sugars.
2. Enter in the table the missing information "Structure and functions of the organic substances of the cell."
3. What is meant by protein denaturation?
Protein denaturation is the loss of a protein's natural structure.
Nucleic acids, ATP and other organic compounds of the cell.
1. Give definitions of concepts.
Nucleic acids are biopolymers consisting of monomers - nucleotides.
ATP is a compound composed of the nitrogenous base adenine, a ribose carbohydrate, and three phosphoric acid residues.
A nucleotide is a nucleic acid monomer that consists of a phosphate group, a five-carbon sugar (pentose), and a nitrogenous base.
A macroergic bond is a bond between phosphoric acid residues in ATP.
Complementarity is the spatial mutual correspondence of nucleotides.
2. Prove that nucleic acids are biopolymers.
Nucleic acids are made up of a large number of repeating nucleotides and have a mass of 10,000 to several million carbon units.
3. Describe the structural features of the nucleotide molecule.
A nucleotide is a compound of three components: a phosphoric acid residue, a five-carbon sugar (ribose), and one of the nitrogenous compounds (adenine, guanine, cytosine, thymine, or uracil).
4. What is the structure of a DNA molecule?
DNA is a double helix made up of many nucleotides that are joined together in sequence. covalent bonds between the deoxyribose of one and the phosphoric acid residue of the other nucleotide. The nitrogenous bases, which are located on one side of the backbone of one chain, are connected by H-bonds with the nitrogenous bases of the second chain according to the principle of complementarity.
5. Using the principle of complementarity, build the second strand of DNA.
T-A-T-C-A-G-A-C-C-T-A-C
A-T-A-G-T-C-T-G-G-A-T-G.
6. What are the main functions of DNA in a cell?
With the help of four types of nucleotides in DNA, the entire important information in a cell about an organism that is passed on to subsequent generations.
7. How does an RNA molecule differ from a DNA molecule?
RNA is a single strand smaller than DNA. Nucleotides contain the sugar ribose, not deoxyribose, as in DNA. The nitrogenous base, instead of thymine, is uracil.
8. What is common in the structure of DNA and RNA molecules?
Both RNA and DNA are biopolymers made up of nucleotides. In nucleotides, the common structure is the presence of a phosphoric acid residue and adenine, guanine, and cytosine bases.
9. Fill in the table "RNA types and their functions in the cell."
10. What is ATP? What is its role in the cell?
ATP - adenosine triphosphate, macroergic compound. Its functions are the universal keeper and carrier of energy in the cell.
11. What is the structure of the ATP molecule?
ATP is made up of three residues of phosphoric acid, ribose, and adenine.
12. What are vitamins? What two large groups are they divided into?
Vitamins are biologically active organic compounds that play an important role in metabolic processes. They are divided into water-soluble (C, B1, B2, etc.) and fat-soluble (A, E, etc.).
13. Fill in the table "Vitamins and their role in the human body."
The cell is the elementary unit of the structure of living organisms. All living things - be it humans, animals, plants, fungi or bacteria - are basically cells. In someone's body there are a lot of these cells - hundreds of thousands of cells make up the body of mammals and reptiles, and in someone there are few - many bacteria consist of only one cell. But the number of cells is not as important as their presence.
It has long been known that cells have all the properties of a living thing: they breathe, feed, multiply, adapt to new conditions, and even die. And, like all living things, cells contain organic and inorganic substances.
Much more, because it is also water, and of course, the largest part of the department called "inorganic substances of the cell" is given to water - it makes up 40-98% of the total volume of the cell.
Water in the cell performs many important functions: it ensures the elasticity of the cell, the speed of chemical reactions taking place in it, the movement of incoming substances through the cell and their removal. In addition, many substances dissolve in water, it can participate in chemical reactions, and it is water that is responsible for the thermoregulation of the whole organism, since water has good thermal conductivity.
In addition to water, the inorganic substances of the cell also include many mineral substances, which are divided into macroelements and microelements.
Macronutrients include substances such as iron, nitrogen, potassium, magnesium, sodium, sulfur, carbon, phosphorus, calcium and many others.
Trace elements are, for the most part, heavy metals such as boron, manganese, bromine, copper, molybdenum, iodine and zinc.
Also in the body there are ultramicroelements, including gold, uranium, mercury, radium, selenium and others.
All inorganic substances of the cell play their own, important role. So, nitrogen is involved in a great variety of compounds - both protein and non-protein, promotes the formation of vitamins, amino acids, pigments.
Calcium is a potassium antagonist and serves as a glue for plant cells.
Iron is involved in the process of respiration, is part of the hemoglobin molecules.
Copper is responsible for the formation of blood cells, heart health and good appetite.
Boron is responsible for the growth process, especially in plants.
Potassium ensures the colloidal properties of the cytoplasm, the formation of proteins and the normal functioning of the heart.
Sodium also ensures the correct rhythm of cardiac activity.
Sulfur is involved in the formation of some amino acids.
Phosphorus is involved in the formation of a huge number of essential compounds, such as nucleotides, some enzymes, AMP, ATP, ADP.
And only the role of ultramicroelements is still absolutely unknown.
But the inorganic substances of the cell alone could not make it complete and alive. Organic matter is no less important than they are.
These include carbohydrates, lipids, enzymes, pigments, vitamins, and hormones.
Carbohydrates are divided into monosaccharides, disaccharides, polysaccharides and oligosaccharides. Mono-di- and polysaccharides are the main source of energy for the cell and the body, but water-insoluble oligosaccharides stick together connective tissue and protect cells from adverse external influences.
Lipids are divided into proper fats and lipoids - fat-like substances that form oriented molecular layers.
Enzymes are catalysts that speed up biochemical processes in the body. In addition, enzymes reduce the amount of energy consumed to impart reactivity to the molecule.
Vitamins are necessary for the regulation of the oxidizability of amino acids and carbohydrates, as well as for full growth and development.
Hormones are necessary to regulate the life of the body.
These include water and mineral salts.
Water necessary for the implementation of life processes in the cell. Its content is 70-80% of the mass of the cell. The main functions of water:
is a universal solvent;
is the environment in which biochemical reactions take place;
determines the physiological properties of the cell (elasticity, volume);
participates in chemical reactions;
maintains the thermal balance of the body due to the high heat capacity and thermal conductivity;
is the main means for the transport of substances.
mineral salts present in the cell in the form of ions: cations K + , Na + , Ca 2+ , Mg 2+ ; anions - Cl -, HCO 3 -, H 2 PO 4 -.
3. Organic substances of the cell.
The organic compounds of a cell consist of many repeating elements (monomers) and are large molecules - polymers. These include proteins, fats, carbohydrates and nucleic acids. Their content in the cell: proteins -10-20%; fats - 1-5%; carbohydrates - 0.2-2.0%; nucleic acids - 1-2%; low molecular weight organic substances - 0.1-0.5%.
Squirrels - high-molecular (high molecular weight) organic substances. The structural unit of their molecule is an amino acid. 20 amino acids take part in the formation of proteins. The composition of the molecule of each protein includes only certain amino acids in the order characteristic of this protein. The amino acid has the following formula:
H 2 N - CH - COOH
The composition of amino acids includes NH 2 - an amino group with basic properties; COOH is a carboxyl group with acidic properties; radicals that distinguish amino acids from each other.
There are primary, secondary, tertiary and quaternary protein structures. Amino acids linked together by peptide bonds determine its primary structure. Proteins of the primary structure are connected in a spiral with the help of hydrogen bonds and form a secondary structure. Polypeptide chains, twisting in a certain way into a compact structure, form a globule (ball) - the tertiary structure of the protein. Most proteins have a tertiary structure. It should be noted that amino acids are active only on the surface of the globule. Proteins with a globular structure combine and form a quaternary structure (for example, hemoglobin). When exposed to high temperature, acids and other factors, complex protein molecules are destroyed - protein denaturation. When conditions improve, the denatured protein is able to restore its structure if its primary structure is not destroyed. This process is called renaturation.
Proteins are species-specific: each species of animal is characterized by a set of certain proteins.
There are simple and complex proteins. Simple ones consist only of amino acids (for example, albumins, globulins, fibrinogen, myosin, etc.). The composition of complex proteins, in addition to amino acids, also includes other organic compounds, for example, fats and carbohydrates (lipoproteins, glycoproteins, etc.).
Proteins perform the following functions:
enzymatic (for example, the enzyme amylase breaks down carbohydrates);
structural (for example, they are part of membranes and other cell organelles);
receptor (for example, the protein rhodopsin contributes to better vision);
transport (for example, hemoglobin carries oxygen or carbon dioxide);
protective (for example, immunoglobulin proteins are involved in the formation of immunity);
motor (for example, actin and myosin are involved in the contraction of muscle fibers);
hormonal (for example, insulin converts glucose into glycogen);
energy (when splitting 1 g of protein, 4.2 kcal of energy is released).
Fats (lipids) - compounds of trihydric alcohol glycerol and high molecular weight fatty acids. Chemical formula fat:
CH 2 -O-C(O)-R¹
CH 2 -O-C(O)-R³, where the radicals may be different.
Functions of lipids in the cell:
structural (take part in the construction of the cell membrane);
energy (with the breakdown of 1 g of fat in the body, 9.2 kcal of energy is released);
protective (preserve from heat loss, mechanical damage);
fat is a source of endogenous water (when 10 g of fat is oxidized, 11 g of water is released);
regulation of metabolism.
Carbohydrates - their molecule can be represented by the general formula C n (H 2 O) n - carbon and water.
Carbohydrates are divided into three groups: monosaccharides (include one sugar molecule - glucose, fructose, etc.), oligosaccharides (include from 2 to 10 monosaccharide residues: sucrose, lactose) and polysaccharides (high molecular weight compounds - glycogen, starch, etc.).
Functions of carbohydrates:
serve as initial elements for the construction of various organic substances, for example, during photosynthesis - glucose;
the main source of energy for the body, when they are decomposed using oxygen, more energy is released than when fat is oxidized;
protective (for example, the mucus secreted by various glands contains a lot of carbohydrates; it protects the walls of hollow organs (bronchi, stomach, intestines) from mechanical damage; having antiseptic properties);
structural and supporting functions: are part of the plasma membrane.
Nucleic acids are phosphorus-containing biopolymers. These include deoxyribonucleic (DNA) and ribonucleic (RNA) acids.
DNA - the largest biopolymers, their monomer is nucleotide. It consists of residues of three substances: a nitrogenous base, a carbohydrate deoxyribose and phosphoric acid. There are 4 nucleotides involved in the formation of the DNA molecule. Two nitrogenous bases are derivatives of pyrimidine - thymine and cytosine. Adenine and guanine are classified as purine derivatives.
According to the DNA model proposed by J. Watson and F. Crick (1953), the DNA molecule consists of two strands spirally wrapped around each other.
The two strands of a molecule are held together by hydrogen bonds that occur between them. complementary nitrogenous bases. Adenine is complementary to thymine, and guanine is complementary to cytosine. DNA in cells is located in the nucleus, where it, together with proteins, forms chromosomes. DNA is also found in mitochondria and plastids, where their molecules are arranged in a ring. Main DNA function- storage of hereditary information contained in the sequence of nucleotides that form its molecule, and the transfer of this information to daughter cells.
Ribonucleic acid single-stranded. An RNA nucleotide consists of one of the nitrogenous bases (adenine, guanine, cytosine, or uracil), a ribose carbohydrate, and a phosphoric acid residue.
There are several types of RNA.
Ribosomal RNA(r-RNA) in combination with the protein is part of the ribosomes. Ribosomes carry out protein synthesis. Messenger RNA(i-RNA) carries information about protein synthesis from the nucleus to the cytoplasm. Transfer RNA(t-RNA) is located in the cytoplasm; attaches certain amino acids to itself and delivers them to ribosomes - the site of protein synthesis.
RNA is found in the nucleolus, cytoplasm, ribosomes, mitochondria, and plastids. In nature, there is another type of RNA - viral. In some viruses, it performs the function of storing and transmitting hereditary information. In other viruses, this function is performed by viral DNA.
Adenosine triphosphoric acid
(ATP) - is a special nucleotide formed by the nitrogenous base adenine, carbohydrate ribose and three residues of phosphoric acid. 
ATP is a universal source of energy necessary for biological processes occurring in the cell. The ATP molecule is very unstable and is capable of splitting off one or two phosphate molecules with the release of a large amount of energy. This energy is spent on ensuring all the vital functions of the cell - biosynthesis, movement, generation of an electrical impulse, etc. The bonds in the ATP molecule are called macroergic. The cleavage of phosphate from an ATP molecule is accompanied by the release of 40 kJ of energy. ATP synthesis occurs in mitochondria.
Water. Of the inorganic substances that make up the cell, water is the most important. Its amount is from 60 to 95% of the total mass of the cell. Water plays an essential role in the life of cells and living organisms in general. In addition to being part of their composition, for many organisms it is also a habitat.
The role of water in the cell is determined by its unique chemical and physical properties, associated mainly with the small size of the molecules, with the polarity of its molecules and with their ability to form hydrogen bonds with each other.
Water as a component of biological systems performs the following important functions:
- Water- universal solvent for polar substances, such as salts, sugars, alcohols, acids, etc. Substances that are highly soluble in water are called hydrophilic. When a substance goes into solution, its molecules or ions are allowed to move more freely; the reactivity of the substance increases accordingly. It is for this reason that most of the chemical reactions in the cell proceed in aqueous solutions. Its molecules are involved in many chemical reactions, for example, in the formation or hydrolysis of polymers. In the process of photosynthesis, water is an electron donor, a source of hydrogen ions and free oxygen.
- Water does not dissolve or mix with non-polar substances, since it cannot form hydrogen bonds with them. Substances that are insoluble in water are called hydrophobic. Hydrophobic molecules or their parts are repelled by water, and in its presence are attracted to each other. Such interactions play an important role in ensuring the stability of membranes, as well as many protein molecules, nucleic acids, and a number of subcellular structures.
- Water has a high specific heat capacity. It takes a lot of energy to break the hydrogen bonds that hold water molecules together. This property ensures the maintenance of the thermal balance of the body with significant temperature fluctuations in environment. In addition, water is different high thermal conductivity, which allows the body to maintain the same temperature throughout its volume.
- Water is characterized high heat of vaporization, That is, the ability of molecules to carry away with them a significant amount of heat while cooling the body. Due to this property of water, which is manifested during sweating in mammals, thermal dyspnea in crocodiles and other animals, transpiration in plants, their overheating is prevented.
- Water is exclusively high surface tension. This property is very importance for adsorption processes, for the movement of solutions through tissues (blood circulation, ascending and descending currents in plants). For many small organisms, surface tension allows them to float or glide across the surface of the water.
- Water provides movement of substances in the cell and the body, the absorption of substances and the excretion of metabolic products.
- In plants, water determines turgor cells, and in some animals performs support functions being a hydrostatic skeleton (round and annelids, echinoderms).
- Water - component lubricating fluids(synovial - in the joints of vertebrates, pleural - in the pleural cavity, pericardial - in the pericardial sac) and slime(facilitate the movement of substances through the intestines, create humid environment on the mucous membranes of the respiratory tract). It is part of saliva, bile, tears, sperm, etc.
mineral salts. Inorganic substances in the cell, other than water, precspavlevy mineral salts. Molecules of salts in an aqueous solution decompose into cations and anions. The most important are cations (K +, Na +, Ca 2+, Mg: +, NH 4 +) and anions (C1, H 2 P0 4 -, HP0 4 2-, HC0 3 -, NO3 2--, SO 4 2-) Not only the content, but also the ratio of ions in the cell is essential.
The difference between the number of cations and anions on the surface and inside the cell provides the occurrence action potential, what underlies the emergence of nervous and muscular excitation. The difference in the concentration of ions on different sides of the membrane is due to the active transfer of substances through the membrane, as well as the conversion of energy.
From the inorganic substances of the cell water makes up about 65% of its mass: in young rapidly growing cells up to 95%, in old cells - about 60%. The role of water in cells is very large, it is a medium and a solvent, participates in most chemical reactions, the movement of substances, thermoregulation, the formation of cellular structures, determines the volume and elasticity of the cell. Most substances enter the body and are excreted from it in an aqueous solution.
organic matter- make up 20-30% of the cell composition. They can be simple(amino acids, glucose, fatty acids) and complex(proteins, polysaccharides, nucleic acids, lipids). The most important are proteins, fats, carbohydrates, nucleic acids.
Proteins are the basic and most complex substances of any cell. The size of a protein molecule is hundreds and thousands of times larger than the molecules of inorganic compounds. Protein molecules are formed from simple connections amino acids (natural proteins contain 20 amino acids). Combining in different sequences and quantities, they form a wide variety (up to 1000) of proteins. Their role in the life of the cell is enormous: construction material organism, catalysts (enzyme proteins accelerate chemical reactions), transport (blood hemoglobin delivers oxygen and nutrients to cells and carries away carbon dioxide and decay products). Proteins perform a protective function, energy. Carbohydrates are organic substances composed of carbon, hydrogen and oxygen. The simplest of these are monosaccharides - hexose, fructose, glucose (found in fruits, honey), galactose (in milk) and polysaccharides - consisting of several simple carbohydrates. These include starch and glycogen. Carbohydrates are the main source of energy for all forms of cellular activity (movement, biosynthesis, secretion, etc.) and play the role of reserve substances. Lipids are water-insoluble fats and fat-like substances. They are the main structural component biological membranes. Lipids perform an energy function, they contain fat-soluble vitamins. Nucleic acids - (from the Latin word "nucleus" - nucleus) - are formed in the nucleus of the cell. They are of two types: deoxyribonucleic acids (DNA) and ribonucleic acids (RNA). Their biological role is very great. They determine the synthesis of proteins and the transmission of hereditary information.