As we already know, the cell is composed of organic and inorganic chemicals. The main inorganic substances that make up the cell are salts and water.
Water as a component of living
Water is the dominant component of all organisms. Important biological functions of water are carried out due to the unique properties of its molecules, in particular the presence of dipoles, which make possible occurrence hydrogen bonds between cells.
Thanks to water molecules in the body of living beings, the processes of thermal stabilization and thermoregulation take place. The process of thermoregulation occurs due to the high heat capacity of water molecules: external temperature drops do not affect temperature changes inside the body.
Thanks to water organs human body retain their elasticity. Water is one of the main components of lubricating fluids required for the joints of the vertebrates or the pericardium.
It is included in mucus, which facilitates the movement of substances through the intestines. Water is a constituent of bile, tears and saliva.
Salts and other inorganic substances
In addition to water, the cells of a living organism contain such inorganic substances like acids, bases and salts. Most essential in the life of the organism have Mg2 +, H2PO4, K, CA2, Na, C1-. Weak acids guarantee a stable internal cell environment (slightly alkaline).
The concentration of ions in the intercellular substance and inside the cell can be different. So, for example, Na + ions are concentrated only in the intercellular fluid, while K + is contained exclusively in the cell.
A sharp decrease or increase in the number of certain ions in the composition of the cell, not only to its dysfunction, but also to death. For example, a decrease in the amount of Ca + in a cell causes convulsions inside the cell and its further death.
Some inorganic substances often interact with fats, proteins and carbohydrates. So a striking example is organic compounds with phosphorus and sulfur.
Sulfur, which is part of protein molecules, is responsible for the formation of molecular bonds in the body. Thanks to the synthesis of phosphorus and organic substances, energy is released from protein molecules.
Calcium salts
The normal development of bone tissue, as well as the functioning of the head and spinal cord contribute to calcium salts. The exchange of calcium in the body is carried out at the expense of vitamin D. An excess or deficiency of calcium salts leads to dysfunction of the body.
The cell contains about 70 elements Periodic table elements of Mendeleev, and 24 of them are present in all types of cells. All elements present in the cell are divided, depending on their content in the cell, into group:
- macronutrients- H, O, N, C ,. Mg, Na, Ca, Fe, K, P, Cl, S;
- trace elements- B, Ni, Cu, Co, Zn, Mb, etc .;
- ultramicroelements- U, Ra, Au, Pb, Hg, Se, etc.
- organogens(oxygen, hydrogen, carbon, nitrogen),
- macronutrients,
- trace elements.
The cell contains molecules inorganic and organic connections.
Inorganic compounds of the cell
– water and inorganic ions.
Water- the most important inorganic substance of the cell. All bio chemical reactions occur in aqueous solutions. The water molecule has a nonlinear spatial structure and polarity. Hydrogen bonds are formed between individual water molecules, which determine the physical and Chemical properties water.
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Physical properties of water |
Significance for biological processes |
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High heat capacity (due to hydrogen bonds between molecules) and thermal conductivity (due to small size molecules) |
Transpiration |
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Transparency in the visible part of the spectrum |
Highly productive biocenoses of ponds, lakes, rivers (due to the possibility of photosynthesis at shallow depths) |
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Almost complete incompressibility (due to intermolecular bonding forces) |
Maintaining the shape of organisms: the shape of the succulent organs of plants, the position of grasses in space, the hydrostatic skeleton of roundworms, jellyfish, amniotic fluid supports and protects the mammalian fetus |
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Molecular mobility (due to weakness of hydrogen bonds) |
Osmosis: the flow of water from the soil; plasmolysis |
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Viscosity (hydrogen bonds) |
Lubricating properties: synovial fluid in joints, pleural fluid |
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Solvent (molecular polarity) |
Blood, interstitial fluid, lymph, gastric juice, saliva, in animals; cell sap in plants; aquatic organisms use oxygen dissolved in water |
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The ability to form a hydration shell around macromolecules (due to the polarity of the molecules) |
Dispersion medium in the colloidal system of the cytoplasm |
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The value of the surface tension forces optimal for biological systems (due to the forces of intermolecular adhesion) |
Aqueous solutions are a means of transporting substances in the body |
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Expansion during freezing (due to the formation of each molecule of the maximum number - 4 - hydrogen bonds_ |
Ice is lighter than water, performs the function of a heat insulator in reservoirs |
Inorganic ions:
cations K +, Na +, Ca2 +, Mg2 + and anions Cl–, NO3-, PO4 2-, CO32-, HPO42-.
The difference between the number of cations and anions (Na +
, TO +
, Сl-) on the surface and inside the cell provides the emergence of an action potential, which underlies nervous and muscle excitement.
Phosphoric acid anions create phosphate buffer system, which maintains the pH of the intracellular environment of the body at the level of 6-9.
Carbonic acid and its anions create bicarbonate buffer system and maintain the pH of the extracellular environment (blood plasma) at 7-4.
Nitrogen compounds serve source mineral nutrition, synthesis of proteins, nucleic acids.
Phosphorus atoms are part of nucleic acids, phospholipids, as well as the bones of vertebrates, the chitinous cover of arthropods.
Calcium ions are part of the bone substance; they are also necessary for muscle contraction and blood clotting.
Table. The role of macronutrients at the cellular and organismal level of organization.
Table.
Thematic assignments
Part A
A1. The polarity of water is due to its ability
1) conduct heat
3) dissolve sodium chloride
2) absorb heat
4) dissolve glycerin
A2... Children with rickets should be given drugs containing
1) iron
2) potassium
3) calcium
4) zinc
A3... Conduction of a nerve impulse is provided by ions:
1) potassium and sodium
2) phosphorus and nitrogen
3) iron and copper
4) oxygen and chlorine
A4... Weak bonds between water molecules in its liquid phase are called:
1) covalent
2) hydrophobic
3) hydrogen
4) hydrophilic
A5... The composition of hemoglobin includes
1) phosphorus
2) iron
3) sulfur
4) magnesium
A6... Select a group chemical elements, necessarily included in the composition of proteins
1) Na, K, O, S
2) N, P, C, Cl
3) C, S, Fe, O
4) C, H, O, N
A7... Patients with hypofunction thyroid gland give drugs containing
1) iodine
2) iron
3) phosphorus
4) sodium
Part B
IN 1... Select the functions of the water in the cage
1) energy
2) enzymatic
3) transport
4) construction
5) lubricating
6) thermoregulation
IN 2... Select only the physical properties of water
1) the ability to dissociate
2) hydrolysis of salts
3) density
4) thermal conductivity
5) electrical conductivity
6) electron donation
Part C
C1... What physical properties of water determine its biological significance?
The cells contain inorganic and organic substances (compounds).
Inorganic substances of the cell- this is water, various mineral salts, carbon dioxide, acids and bases.
| Inorganic substances of the cell | |
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Water (makes up 70-80% of the cell mass) |
Mineral salts (make up 1-1.5% of the total cell mass) |
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Water is an essential component of the contents of a living cell. Water gives the cell elasticity and volume, ensures the constancy of its composition, participates in chemical reactions and in the construction of organic molecules, makes it possible for all processes of the cell's life to proceed. Water is a solvent for chemicals that enter and exit the cell.
Water(hydrogen oxide, H 2 O) is a transparent liquid that has no color (in a small volume), odor and taste. V natural conditions contains solutes (salts, gases). Water plays a key role in the life of cells and living organisms, in the formation of climate and weather.
The amount of water in the cell is 60 to 95% of the total mass. The role of water in the cell is determined by its unique chemical and physical properties associated with the small size of the molecules, their polarity and the ability to form hydrogen bonds.
Water as a component of biological systems
- Water is a universal solvent for polar substances - salts, sugars, acids, etc. It increases their reactivity, so most of the chemical reactions in the cell take place in aqueous solutions.
- Non-polar substances are insoluble in water (no hydrogen bonds are formed). Being attracted to each other, hydrophobic substances in the presence of water form various complexes (for example, biological membranes).
- The high specific heat capacity of water (i.e., the absorption of a large amount of energy to break hydrogen bonds) ensures the maintenance of the thermal balance of the body during temperature changes environment.
- The high heat of vaporization (the ability of molecules to carry away with them a significant amount of heat when the body cools) prevents the body from overheating.
- High surface tension ensures the movement of solutions through tissues.
- Water ensures the elimination of metabolic products.
- In plants, water maintains cell turgor, in some animals it performs supporting functions (hydrostatic skeleton).
- Water is part of various biological fluids (blood, saliva, mucus, bile, tears, semen, synovial and pleural fluids, etc.).
The water molecule has angular shape: hydrogen atoms in relation to oxygen form an angle of approximately 104.5 °.
Due to the high electronegativity of the oxygen atom, the O – H bond is polar. Hydrogen atoms carry partial positive charge and the oxygen atom is partial negative.
A dipole creates a magnetic field around itself at large distances compared to its size.
When water evaporates, the destruction of hydrogen bonds requires a lot of energy.
| Water content in different organisms and organs (in%) | |||
| Plants or plant parts | Animals or animal organs | ||
| Seaweed | up to 98 | Jellyfish | up to 95 |
| Higher plants | from 70 to 80 | Grape snails | 80 |
| Tree leaves | from 50 to 97 | The human body | 60 |
| Potato tubers | 75 | Human blood | 79 |
| Juicy fruits | up to 95 | Human muscles | from 77 to 83 |
| Lignified plant parts | from 40 to 80 | Human heart | 70 |
| Dry seeds | from 5 to 9 | ||
Inorganic substances in the cell, except for water, are represented mineral salts.
Mineral salts make up only 1-1.5% of the total cell mass, but their role is significant. In dissolved form, they are a necessary medium for the chemical processes that determine the life of the cell.
The cells contain many different salts... Animals, using the excretory system, remove excess salts from the body, and in plants they accumulate and crystallize in various organelles or in vacuoles. Most often these are calcium salts. Their shape in plant cells can be different: needles, rhombuses, crystals - single or fused together (druses).
Salt molecules in an aqueous solution decompose into cations and anions. The most important are cations (К +, Na +, Ca 2+, Mg +, NH 4 +) and anions (Сl -, Н 2 Р0 4 -, НР0 4 2-, НС0 3 -, NO 3 -, SO 4 2 -).
The concentration of different ions is not the same in different parts cells as well as in the cell and the environment. The concentration of sodium ions is always higher outside the cell, and potassium and magnesium ions - inside the cell. The difference between the number of cations and anions inside the cell and on its surface ensures active transport of substances across the membrane.
The buffer properties of the cytoplasm depend on the concentration of salts inside the cell - the ability of the cell to maintain a certain concentration of hydrogen ions under conditions of constant formation of acidic and alkaline substances during metabolism.
Anions of phosphoric acid create a phosphate buffer system that maintains the pH of the intracellular environment of the body at 6.9.
Carbonic acid and its anions form a bicarbonate buffer system that maintains the pH of the extracellular medium (blood plasma) at 7.4.
Some ions are involved in the activation of enzymes, the creation of osmotic pressure in the cell, in the processes of muscle contraction, blood coagulation, etc. A number of cations and anions are necessary for the synthesis of important organic substances.
From inorganic substances cells water makes up about 65% of its mass: in young fast-growing cells up to 95%, in old - about 60%. The role of water in cells is very large, it is a medium and solvent, it is involved in most chemical reactions, the movement of substances, thermoregulation, the formation of cell structures, and determines the volume and elasticity of the cell. Most substances enter the body and are removed from it in aqueous solution.
Organic matter- make up 20-30% of the cell composition. They may 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 in 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 sequence and quantity, they form a wide variety (up to 1000) 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, energetic function. Carbohydrates are organic substances made up of carbon, hydrogen and oxygen. The simplest of them are monosaccharides - hexose, fructose, glucose (found in fruits, honey), galactose (in milk) and polysaccharides - consisting of several simple carbohydrates. These include starch, 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 energetic function, they contain fat-soluble vitamins. Nucleic acids - (from the Latin word "nucleus" - nucleus) - are formed in the cell nucleus. 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.
A cell is an elementary unit of a living, possessing all the characteristics of an organism: the ability to reproduce, grow, exchange substances and energy with the environment, irritability, and the constancy of chemical sotsava.
Macronutrients - elements, the amount of which in a 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 a cell ranges from 0.001% to 0.000001% of body weight. Examples are boron, copper, cobalt, zinc, iodine, etc.
Ultramicroelements - elements, the content of which in the cell does not exceed 0.000001% of the 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 elementary chemical composition living 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 nonliving organisms.
Water is one of the most widespread inorganic substances in nature, the molecule of which consists of two hydrogen atoms and one oxygen atom.
2. Draw a diagram "Water structure".
3. What features of the structure of water molecules give it unique properties without which life is impossible?
The structure of a 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 different aggregate states 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 the provision of its vital processes?
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 a 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 giving up protons, depending on their entry into the medium from the outside or, on the contrary, removal from the medium, while the pH will not change. The presence of buffer systems is necessary in a living organism, since due to changes in environmental conditions, pH can vary greatly, 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 weight organic substances consisting of alpha-amino acids linked in a chain by a peptide bond.
Lipids are a wide group of natural organic compounds, including fats and fat-like substances. Molecules of simple lipids are composed of alcohol and fatty acids, complex - 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 "The structure and functions of organic substances in the cell."
3. What is meant by protein denaturation?
Protein denaturation is the loss of its natural structure by a protein.
Nucleic acids, ATP and other organic compounds of the cell.
1. Give definitions of concepts.
Nucleic acids are biopolymers composed of monomers - nucleotides.
ATP is a compound consisting of the nitrogenous base of adenine, the carbohydrate ribose, and three phosphoric acid residues.
A nucleotide is a nucleic acid monomer that is composed of a phosphate group, a five-carbon sugar (pentose), and a nitrogenous base.
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 composed of a large number of repetitive 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 the DNA molecule?
DNA is a double helix, consisting of many nucleotides, which are sequentially connected to each other due to 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 linked by H-bonds with the nitrogenous bases of the second chain according to the principle of complementarity.
5. Applying 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, DNA contains all important information in the cell about the body, which 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. The 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 bases of adenine, guanine, cytosine.
9. Fill in the table "Types of RNA and their functions in the cell."
10. What is ATP? What is its role in the cell?
ATP - adenosine triphosphate, a high-energy compound. Its functions are a universal keeper and carrier of energy in the cell.
11. What is the structure of the ATP molecule?
ATP consists of three phosphoric acid residues, 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."