Biology [A complete guide to preparing for the exam] Lerner Georgy Isaakovich
2.3.1. inorganic substances cells
The cell contains about 70 elements of the periodic system of 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 groups:
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.
The cell contains molecules inorganic And organic connections.
Inorganic compounds of the cell - water And inorganic ions.
Water is the most important inorganic substance of the cell. All biochemical reactions take place in aqueous solutions. The water molecule has a non-linear spatial structure and has polarity. Hydrogen bonds are formed between individual water molecules, which determine the physical and Chemical properties water.
Physical properties of water: Since water molecules are polar, water has the property of dissolving polar molecules of other substances. Substances that are soluble in water are called hydrophilic. Substances that are insoluble in water are called hydrophobic.
Water has a high specific heat. To break the numerous hydrogen bonds that exist between water molecules, it is required to absorb a large number of energy. Remember how long it takes for a kettle to boil. This property of water ensures the maintenance of heat balance in the body.
It takes a lot of energy to evaporate water. The boiling point of water is higher than that of many other substances. This property of water protects the body from overheating.
Water can be in three states of aggregation- liquid, solid and gaseous.
Hydrogen bonds determine the viscosity of water and the adhesion of its molecules to the molecules of other substances. Due to the forces of adhesion of molecules, a film is created on the surface of the water, which has such a characteristic as surface tension.
When cooled, the movement of water molecules slows down. The number of hydrogen bonds between molecules becomes maximum. Water reaches its highest density at 4 C?. As water freezes, it expands (requires room for hydrogen bonds to form) and its density decreases. That's why ice floats.
biological functions water. Water ensures the movement of substances in the cell and body, the absorption of substances and the excretion of metabolic products. In nature, water carries waste products to soils and water bodies.
Water is an active participant in metabolic reactions.
Water is involved in the formation of lubricating fluids and mucus, secrets and juices in the body. These fluids are found in the joints of vertebrates, in the pleural cavity, in the pericardial sac.
Water is part of the mucus, which facilitate the movement of substances through the intestines, create a humid environment on the mucous membranes of the respiratory tract. The secrets secreted by some glands and organs also have a water base: saliva, tears, bile, sperm, etc.
inorganic ions. The inorganic ions of the cell include: cations K +, Na +, Ca 2+, Mg 2+, NH 3 + and anions Cl -, NO 3 -, H 2 PO 4 -, NCO 3 -, HPO 4 2-.
The difference between the number of cations and anions (Na + , Ka + , Cl -) on the surface and inside the cell provides the emergence of an action potential, which underlies the nervous and muscle excitation.
Anions phosphoric acids create phosphate buffer system, maintaining the pH of the intracellular environment of the body at the level of 6-9.
Carbonic acid and its anions create a bicarbonate buffer system and maintain the pH of the extracellular medium (blood plasma) at the level of 7-4.
Nitrogen compounds serve as a source of mineral nutrition, protein synthesis, nucleic acids. Phosphorus atoms are part of nucleic acids, phospholipids, and bones of vertebrates, chitinous cover arthropods. Calcium ions are part of the bone substance; they are also necessary for the implementation of muscle contraction, blood clotting.
EXAMPLES OF TASKS
A1. The polarity of water determines 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 3) iron and copper
2) phosphorus and nitrogen 4) oxygen and chlorine
A4. Weak bonds between water molecules in its liquid phase are called:
1) covalent 3) hydrogen
2) hydrophobic 4) hydrophilic
A5. Hemoglobin contains
1) phosphorus 2) iron 3) sulfur 4) magnesium
A6. Choose a group chemical elements, which must be present in proteins
A7. Patients with hypothyroidism are given medications containing
Part B
IN 1. Select the functions of the water in the cage
1) energy 4) construction
2) enzymatic 5) lubricating
3) transport 6) thermoregulatory
AT 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 WITH
C1. What are the physical properties of water that determine it? biological significance?
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author Lerner Georgy Isaakovich2.3. The chemical organization of the cell. The relationship of the structure and functions of inorganic and organic matter(proteins, nucleic acids, carbohydrates, lipids, ATP) that make up the cell. Justification of the relationship of organisms based on analysis chemical composition their
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From the book How to take care of yourself if you are over 40. Health, beauty, harmony, energy author Karpukhina Victoria VladimirovnaWater. Of the inorganic substances that make up the cell, water is the most important. Its amount is from 60 to 95% of the total cell mass. 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 is a universal solvent for polar substances, such as salts, sugars, alcohols, acids, etc. Substances that are readily 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. Exactly because of this reason most of chemical reactions in the cell proceeds in aqueous solutions. Its molecules are involved in many chemical reactions, for example, during 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 has a high thermal conductivity, which allows the body to maintain the same temperature throughout its volume.
Water is characterized by a high heat of vaporization, i.e., the ability of molecules to carry away a significant amount of heat with them while cooling the body. Due to this property of water, which is manifested during sweating in mammals, thermal shortness of breath in crocodiles and other animals, transpiration in plants, their overheating is prevented.
Water has an exceptionally high surface tension. This property is very important for adsorption processes, for the movement of solutions through tissues (blood circulation, ascending and descending currents in plants). many small organisms surface tension allows you to stay on the water or slide on its surface.
Water ensures the movement of substances in the cell and body, the absorption of substances and the excretion of metabolic products.
In plants, water determines the turgor of cells, and in some animals it performs supporting functions, being a hydrostatic skeleton (round and annelids, echinoderms).
Water is an integral part of lubricating fluids (synovial - in the joints of vertebrates, pleural - in the pleural cavity, pericardial - in the pericardial sac) and mucus (facilitate the movement of substances through the intestines, create a 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, except for water, contain mineral salts. Salt molecules in aqueous solution break down into cations and anions. Highest value have cations (K+, Na+, Ca2+, Mg:+, NH4+) and anions (C1, H2P04 -, HP042-, HC03 -, NO32--, SO4 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 emergence of an action potential, which underlies the occurrence of nerve and muscle 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.
Phosphoric acid anions create a phosphate buffer system that maintains the pH of the intracellular environment of the body at a level of 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 (for example, phospholipids, ATP, nucleotides, hemoglobin, hemocyanin, chlorophyll, etc.), as well as amino acids, being sources of nitrogen and sulfur atoms.
Source: N.A. Lemeza L.V. Kamlyuk N.D. Lisov "Biology manual for university applicants
Substances accumulate in the cells of the embryo and more often in its cotyledons, the first germinal leaves. The embryo is a miniature plant with vegetative organs: an embryonic shoot (embryonic stem, cotyledons, embryonic bud) and an embryonic root. Spare substances in endosperm cells (storage tissue) or in cotyledon cells are represented by fats, proteins, carbohydrates, organic acids, ...
At least 40 kJ / mol of energy was spent, which is accumulated in macroergic bonds: Therefore, the main significance of the processes of respiration and photosynthesis is determined by the fact that they supply energy for the synthesis of ATP, with the participation of which most of the work is performed in the cell. Thus, ATP is the main universal energy supplier in the cells of all living organisms. ATP is extremely...
With oxygen, reduction is the removal of oxygen. With the introduction of electronic representations into chemistry, the concept of redox reactions was extended to reactions in which oxygen does not participate. In inorganic chemistry, redox reactions (ORRs) can formally be considered as the movement of electrons from an atom of one reagent (reductant) to an atom of another (...
Living organisms contain a large number of chemical elements. They form two classes of compounds - organic And inorganic.
Inorganic substances that make up the cell.
In the cells of different organisms, about 70 elements of the Periodic Table of Chemical Elements were found by D.I. Mendeleev, but only 24 of them have an established value and are found constantly in all types of cells.
The largest specific gravity in the elemental composition of the cell is oxygen, carbon, hydrogen and nitrogen. These are the so-called basic or biogenic elements. These elements account for more than 95% of the mass of cells, and their relative content in living matter is much higher than in the earth's crust.
Vital are calcium, phosphorus, sulfur, potassium, chlorine, sodium, magnesium and iron. Their content in the cell is calculated in tenths and hundredths of a percent. The listed elements make up a group of macronutrients.
Other chemical elements: copper, cobalt, manganese, molybdenum, zinc, boron, fluorine, chromium, selenium, aluminum, iodine, silicon - are found only in small quantities (less than 0.01% of the mass of cells). They belong to the group of microelements.
The percentage of one or another element in the body in no way characterizes the degree of importance and necessity in the body. So, for example, many trace elements are part of various biologically active substances - enzymes, vitamins, hormones, they affect growth and development, hematopoiesis, cellular respiration processes, etc.
Water. It plays an important 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 a cell is determined by its properties. These properties are quite unique and are associated mainly with the small size of water molecules, with the polarity of its molecules and with their ability to combine with each other by hydrogen bonds.
Water molecules have a non-linear spatial structure. The atoms in a water molecule are held together by polar covalent bonds that link one oxygen atom to two hydrogen atoms. The polarity of covalent bonds is explained in this case by the strong electronegativity of the oxygen atoms with respect to the hydrogen atom; the oxygen atom pulls on itself the electrons of their common electron pairs.
As a result, a partially negative charge arises on the oxygen atom, and a partially positive charge on the hydrogen atoms. Hydrogen bonds form between the oxygen and hydrogen atoms of neighboring water molecules.
Water is an excellent solvent for polar substances such as salts, sugars, alcohols, acids. Substances that are soluble in water are called hydrophilic.
Substances that are insoluble in water are called hydrophobic.
Water has high 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 the environment. In addition, water has high thermal conductivity, which allows the body to maintain the same temperature throughout its volume. Water also has a high heat of vaporization, i.e. the ability of molecules to carry away a significant amount of heat, cooling the body. This property of water is used in sweating in mammals, heat panting in crocodiles, and transpiration (evaporation) in plants, preventing them from overheating.