03.11.2019
Inorganic substances of the cell and their significance briefly. Chemical composition of cells. Inorganic compounds of the cell. Inorganic substances of the cell
Basic properties and levels of organization of living nature
Levels of organization of living systems reflect subordination and hierarchy structural organization life:
Molecular genetic - individual biopolymers (DNA, RNA, proteins);
Cellular - an elementary self-reproducing unit of life (prokaryotes, unicellular eukaryotes), tissues, organs;
Organismal - independent existence of an individual;
Population-specific - an elementary evolving unit - a population;
Biogeocenotic - ecosystems consisting of different populations and their habitats;
Biosphere - the entire living population of the Earth, ensuring the circulation of substances in nature.
Nature is the entire existing material world in all its diversity of forms. The unity of nature is manifested in the objectivity of its existence, the commonality of its elemental composition, subordination to the same physical laws, and systematic organization. Various natural systems, both living and non-living, are interconnected and interact with each other. An example of systemic interaction is the biosphere.
Biology is a complex of sciences that study the patterns of development and vital activity of living systems, the reasons for their diversity and adaptability to the environment, the relationship with other living systems and objects of inanimate nature.
The object of biological research is living nature.
The subject of biology research is:
General and specific patterns of organization, development, metabolism, transmission hereditary information;
The diversity of life forms and organisms themselves, as well as their relationships with the environment.
All the diversity of life on Earth is explained evolutionary process and action environment on organisms.
The essence of life is determined by M.V. Wolkenstein as the existence on Earth of “living bodies, which are open self-regulating and self-reproducing systems, built from biopolymers - proteins and nucleic acids.”
Basic properties of living systems:
Metabolism;
Self-regulation;
Irritability;
Variability;
Heredity;
Reproduction;
Chemical composition cells. Inorganic substances of the cell
Cytology is a science that studies the structure and function of cells. The cell is the elementary structural and functional unit of living organisms. The cells of unicellular organisms have all the properties and functions of living systems. The cells of multicellular organisms are differentiated by structure and function.
Atomic composition: the cell contains about 70 elements Periodic table Mendeleev's elements, and 24 of them are present in all types of cells.
Macroelements - H, O, N, C, microelements - Mg, Na, Ca, Fe, K, P, CI, S, ultramicroelements - Zn, Cu, I, F, Mn, Co, Si, etc.
Molecular composition: the cell contains molecules of inorganic and organic compounds.
Inorganic substances of the cell
Water. The water molecule has a nonlinear spatial structure and has polarity. Hydrogen bonds are formed between individual molecules, which determine the physical and Chemical properties water.
Rice. 1. Water molecule Fig. 2. Hydrogen bonds between water molecules
Physical properties of water:
Water can be in three states - liquid, solid and gaseous;
Water is a solvent. Polar water molecules dissolve polar molecules of other substances. Substances that are soluble in water are called hydrophilic. Substances that are insoluble in water are hydrophobic;
High specific heat capacity. To break the hydrogen bonds holding water molecules together, you need to absorb a large number of energy. This property of water ensures the maintenance of thermal balance in the body;
High heat of vaporization. To evaporate water, quite a lot of energy is required. The boiling point of water is higher than that of many other substances. This property of water protects the body from overheating;
Water molecules are in constant motion, they collide with each other in the liquid phase, which is important for metabolic processes;
Cohesion and surface tension. Hydrogen bonds determine the viscosity of water and the adhesion of its molecules with molecules of other substances (cohesion). Due to the adhesive forces of molecules, a film is created on the surface of water, which is characterized by surface tension;
Density. When cooled, the movement of water molecules slows down. The number of hydrogen bonds between molecules becomes maximum. Water has its greatest density at 4°C. When freezing, water expands (space is needed for the formation of hydrogen bonds), and its density decreases, so ice floats on the surface of the water, which protects the reservoir from freezing;
Ability to form colloidal structures. Water molecules form a shell around the insoluble molecules of some substances, preventing the formation of large particles. This state of these molecules is called dispersed (scattered). The smallest particles of substances, surrounded by water molecules, form colloidal solutions (cytoplasm, intercellular fluids).
Biological functions water:
Transport - 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 into soils and water bodies;
Metabolic - water is the medium for all biochemical reactions and an electron donor during photosynthesis; it is necessary for the hydrolysis of macromolecules to their monomers;
Participates in education:
1) lubricating fluids that reduce friction (synovial - in the joints of vertebrates, pleural, in the pleural cavity, pericardial - in the pericardial sac);
2) mucus, which facilitates the movement of substances through the intestines and creates a moist environment on the mucous membranes of the respiratory tract;
3) secretions (saliva, tears, bile, sperm, etc.) and juices in the body.
Inorganic ions. Inorganic ions of the cell are represented by: cations K+, Na+, Ca2+, Mg2+, NH3 and anions Cl-, NOi2-, H2PO4-, HCO3-, HPO42-.
The difference between the amounts of cations and anions on the surface and inside the cell ensures the occurrence of an action potential, which underlies nerve and muscle excitation.
Phosphoric acid anions create a phosphate buffer system that maintains the pH of the body's intracellular environment at a level of 6-9.
Carbonic acid and its anions create a bicarbonate buffer system and maintain the pH of the extracellular environment (blood plasma) at a level of 4-7.
Nitrogen compounds serve as a source mineral nutrition, synthesis of proteins, nucleic acids. Phosphorus atoms are part of nucleic acids, phospholipids, as well as the bones of vertebrates and the chitinous cover of arthropods. Calcium ions are part of the substance of bones; they are also necessary for muscle contraction and blood clotting.
Textbook for grades 10-11
Section I. Cell - a unit of living things
Chapter I. Chemical composition of the cell
Living organisms contain large amounts chemical elements. They form two classes of compounds - organic and inorganic. Chemical compounds whose structure is based on carbon atoms make up hallmark alive. These compounds are called organic. Organic compounds are extremely diverse, but only four classes have universal biological significance: proteins, nucleic acids, carbohydrates and lipids.
§ 1. Inorganic compounds
Biologically important chemical elements. Of the more than 100 chemical elements known to us, about 80 are included in living organisms, and only 24 are known what functions they perform in the cell. The set of these elements is not accidental. Life originated in the waters of the World Ocean, and living organisms consist primarily of those elements that form compounds that are easily soluble in water. Most of these elements are light; their peculiarity is the ability to form strong (covalent) bonds and form many different complex molecules.
The composition of human body cells is dominated by oxygen (more than 60%), carbon (about 20%) and hydrogen (about 10%). Nitrogen, calcium, phosphorus, chlorine, potassium, sulfur, sodium, magnesium taken together account for about 5%. The remaining 13 elements make up no more than 0.1%. The cells of most animals have a similar elemental composition; Only the cells of plants and microorganisms differ. Even those elements that are contained in cells in negligible quantities cannot be replaced by anything and are absolutely necessary for life. Thus, the iodine content in cells does not exceed 0.01%. However, if there is a lack of it in the soil (because of this and in food products) the growth and development of children is delayed. The copper content in animal cells does not exceed 0.0002%. But with a lack of copper in the soil (hence in plants), massive diseases of farm animals occur.
The meaning for the basic element cell is given at the end of this paragraph.
Inorganic (mineral) compounds. Living cells contain a number of relatively simple compounds that are also found in inanimate nature - in minerals and natural waters. These are inorganic compounds.
Water is one of the most common substances on Earth. It covers most of earth's surface. Almost all living things are composed primarily of water. In humans, the water content in organs and tissues varies from 20% (in bone tissue) to 85% (in the brain). About 2/3 of a person’s mass is water, in the body of a jellyfish up to 95% is water, even in dry plant seeds, water is 10-12%.
Water has some unique properties. These properties are so important for living organisms that it is impossible to imagine life without this compound of hydrogen and oxygen.
The unique properties of water are determined by the structure of its molecules. In a water molecule, one oxygen atom is covalently bonded to two hydrogen atoms (Fig. 1). The water molecule is polar (dipole). Positive charges are concentrated on hydrogen atoms, since oxygen is more electronegative than hydrogen.
Rice. 1. Formation of hydrogen bonds in water
The negatively charged oxygen atom of one water molecule is attracted to the positively charged hydrogen atom of another molecule to form a hydrogen bond (Figure 1).
The strength of a hydrogen bond is approximately 15-20 times weaker than a covalent bond. Therefore, the hydrogen bond is easily broken, which is observed, for example, during the evaporation of water. Due to thermal movement molecules in water, some hydrogen bonds are broken, others are formed.
Thus, in liquid water the molecules are mobile, which is important for metabolic processes. Water molecules easily penetrate cell membranes.
Due to the high polarity of its molecules, water is a solvent for other polar compounds. More substances dissolve in water than in any other liquid. That is why in aquatic environment cells carry out many chemical reactions. Water dissolves metabolic products and removes them from the cell and the body as a whole.
Water has a high heat capacity, i.e. the ability to absorb heat with a minimal change in its own temperature. Thanks to this, it protects the cell from sudden changes in temperature. Since a lot of heat is consumed to evaporate water, by evaporating water, organisms can protect themselves from overheating (for example, when sweating).
Water has high thermal conductivity. This property creates the possibility of uniform distribution of heat between body tissues.
Water serves as a solvent for “lubricants”, which are needed wherever there are rubbing surfaces (for example, in joints).
Water has its maximum density at 4°C. Therefore, ice, which has a lower density, is lighter than water and floats on its surface, which protects the reservoir from freezing.
In relation to water, all cell substances are divided into two groups: hydrophilic - “loving water” and hydrophobic - “afraid of water” (from the Greek “hydro” - water, “phileo” - love and “phobos” - fear).
Hydrophilic substances include substances that are highly soluble in water. These are salts, sugars, amino acids. Hydrophobic substances, on the contrary, are practically insoluble in water. These include, for example, fats.
Cell surfaces that separate the cell from external environment, and some other structures consist of water-insoluble (hydrophobic) compounds. Thanks to this, the structural integrity of the cell is maintained. A cell can be figuratively represented as a vessel with water, where biochemical reactions take place that ensure life. The walls of this vessel are insoluble in water. However, they are capable of selectively permeating water-soluble compounds.
In addition to water, among the inorganic substances of the cell we should mention salts, which are ionic compounds. They are formed by cations of potassium, sodium, magnesium and other metals and anions of hydrochloric, carbonic, sulfuric, and phosphoric acids. When such salts dissociate, cations (K +, Na +, Ca 2+, Mg 2+, etc.) and anions (CI -, HCO 3 -, HS0 4 -, etc.) appear in solutions. The concentration of ions on the outer surface of the cell differs from their concentration on inner surface. The different numbers of potassium and sodium ions on the inner and outer surfaces of the cell create a charge difference on the membrane. On the outer surface of the cell membrane there is a very high concentration of sodium ions, and on the inner surface there is a very high concentration of potassium ions and a low concentration of sodium. As a result, a potential difference is formed between the inner and outer surfaces of the cell membrane, which causes the transmission of excitation along a nerve or muscle.
Calcium and magnesium ions are activators of many enzymes, and their deficiency disrupts vital processes in cells. A number of important functions are performed in living organisms by inorganic acids and their salts. Hydrochloric acid creates an acidic environment in the stomach of animals and humans and in special organs of insectivorous plants, accelerating the digestion of food proteins. Phosphoric acid residues (H 3 P0 4), joining a number of enzyme and other cell proteins, change their physiological activity. Residues of sulfuric acid, joining foreign substances insoluble in water, give them solubility and thus contribute to their removal from cells and organisms. Sodium and potassium salts of nitrous and phosphoric acids, calcium salt of sulfuric acid serve as important components of the mineral nutrition of plants; they are applied to the soil as fertilizers to feed plants. The meaning of chemical elements for a cell is given in more detail below.
Biologically important chemical elements of the cell
- What is biological role water in the cage?
- What ions are contained in the cell? What is their biological role?
- What role do the cations contained in the cell play?
Biology [Complete reference book for preparing for the Unified State Exam] Lerner Georgy Isaakovich
2.3.1. Inorganic substances of the cell
The cell contains about 70 elements of Mendeleev's periodic table, 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;
microelements– B, Ni, Cu, Co, Zn, Mb, etc.;
ultramicroelements– U, Ra, Au, Pb, Hg, Se, etc.
Molecules that make up a cell 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 occur in aqueous solutions. The water molecule has a nonlinear spatial structure and has polarity. Hydrogen bonds are formed between individual water molecules, which determine the physical and chemical properties of 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 capacity. To break the numerous hydrogen bonds present between water molecules, a large amount of energy must be absorbed. Remember how long it takes for a kettle to heat up to boiling. This property of water ensures the maintenance of thermal balance in the body.
To evaporate water, quite a lot of energy is required. 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 molecules of other substances. Thanks to the adhesive forces of molecules, a film is created on the surface of water with the following characteristics: surface tension.
When cooled, the movement of water molecules slows down. The number of hydrogen bonds between molecules becomes maximum. Water reaches its greatest density at 4 C?. When water freezes, it expands (needing space for hydrogen bonds to form) and its density decreases. That's why ice floats.
Biological functions of water. Water ensures the movement of substances in the cell and body, the absorption of substances and the removal of metabolic products. In nature, water carries waste products into soils and water bodies.
Water is an active participant in metabolic reactions.
Water is involved in the formation of lubricating fluids and mucus, secretions and juices in the body. These fluids are found in the joints of vertebrates, in the pleural cavity, and in the pericardial sac.
Water is part of mucus, which facilitates the movement of substances through the intestines and creates a moist environment on the mucous membranes of the respiratory tract. The secretions secreted by some glands and organs are also water-based: saliva, tears, bile, sperm, etc.
Inorganic ions. 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 (Nа + , Ka + , Cl -) on the surface and inside the cell ensures the occurrence of an action potential, which underlies nervous and muscle excitation.
Anions phosphorus acids create phosphate buffer system, maintaining the pH of the intracellular environment of the body at a level of 6-9.
Carbonic acid and its anions create a bicarbonate buffer system and maintain the pH of the extracellular environment (blood plasma) at a level of 7-4.
Nitrogen compounds serve as a source of mineral nutrition, synthesis of proteins and nucleic acids. Phosphorus atoms are part of nucleic acids, phospholipids, as well as the bones of vertebrates and the chitinous cover of arthropods. Calcium ions are part of the substance of bones; they are also necessary for muscle contraction and 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 medications containing
1) iron 2) potassium 3) calcium 4) zinc
A3. The 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. Select a group of chemical elements that are necessarily included in proteins
A7. Patients with hypothyroidism are given medications containing
Part B
IN 1. Select the functions of 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) ability to dissociate
2) hydrolysis of salts
3) density
4) thermal conductivity
5) electrical conductivity
6) electron donation
Part WITH
C1. What physical properties of water determine its biological significance?
From the book Big Soviet Encyclopedia(VK) author TSB From the book Great Soviet Encyclopedia (IN) by the author TSB From the book Great Soviet Encyclopedia (KA) by the author TSB From the book Great Soviet Encyclopedia (NOT) by the author TSB From the book Great Soviet Encyclopedia (PL) by the author TSB From the book Great Soviet Encyclopedia (PO) by the author TSB From the book Great Soviet Encyclopedia (ST) by the author TSB From book Short story almost everything in the world by Bryson Bill From the book Biology [Complete reference book for preparing for the Unified State Exam] author Lerner Georgy Isaakovich From the book Pocket Guide to Medical Tests author Rudnitsky Leonid Vitalievich24 CELLS This starts with one cell. The first cell divides to become two, and two become four, and so on. After just 47 doublings, you will have about 10 thousand trillion (10,000,000,000,000,000) cells ready to come to life as a person*.322 And each of these cells knows exactly what
From the book Complete reference book of analyzes and research in medicine author Ingerleib Mikhail Borisovich2.3. Chemical organization of the cell. The relationship between the structure and functions of inorganic and organic substances (proteins, nucleic acids, carbohydrates, lipids, ATP) that make up the cell. Justification of the relationship of organisms based on an analysis of their chemical composition
From the book How to take care of yourself if you are over 40. Health, beauty, slimness, energy author Karpukhina Victoria Vladimirovna2.3.2. Organic substances of the cell. Carbohydrates, lipids Carbohydrates. General formula Сn (H2O)n. Consequently, carbohydrates contain only three chemical elements. Water-soluble carbohydrates. Functions of soluble carbohydrates: transport, protective, signaling,
From the book Encyclopedia of Dr. Myasnikov about the most important things author Myasnikov Alexander Leonidovich4.6. Inorganic substances Inorganic substances in blood plasma and serum (potassium, sodium, calcium, phosphorus, magnesium, iron, chlorine, etc.) determine the physicochemical properties of blood. The amount of inorganic substances in plasma is about 1%. In body tissues they are found in
From the author's book From the author's book From the author's book6.9. Stem cells It is now fashionable to talk about stem cells. When people ask me what I think about this, I answer the question with a question: “Where? In Russia or in the world?” The situations in this area are completely different in Russia and in the world. Intensive research is underway around the world and
Cell as a biological system
Basics of cytology
Basic concepts:
cell theory, cytology, cell - a unit of structure, vital activity, growth and development of an organism, classification of living things, prokaryotes and eukaryotes, chemical organization of the cell, structure of pro- and eukaryotic cells, relationship between the structure and functions of cell organelles, Comparative characteristics cells of plants, animals, fungi and bacteria
The beginning of the study of cells is considered to be 1665: the English naturalist Robert Hooke, examining a section of a balsa tree through a microscope, saw cells that he called "cells". The formation of ideas about the cell occurred in the process of development of biological science.
From the history of the development of ideas about the cell:
| The origin and development of the concept of a cell | 1665 – R. Hooke introduced the concept of “cell”; 1680 – A. Leeuwenhoek discovered single-celled organisms; 1833 - R. Brown discovered dense formations inside plant cells, which he called "nuclei"; 1838 - M. Schleiden came to the conclusion that everything plant cells have a nucleus, T. Schwann discovered nuclei in animal cells. |
| The emergence of cell theory | 1838 - T. Schwann and M. Schleiden summarized knowledge about the cell and formulated the basic principles of cell theory: all plant and animal organisms consist of cells that are similar in structure. |
| Development of cell theory | 1858 - R. Virchow argued that each new cell comes only from a cell as a result of its division; 1858 - K. Baer established that all organisms begin their development from one cell (the mammalian embryo develops from one cell - a fertilized egg). |
Cytology(from Greek kytos) – the science of the cell. The successes of the science of cytology are inextricably linked with the development of research methods: the improvement of the light microscope and the advent of the electron microscope, the use of special dyes that make it possible to selectively identify cellular structures
Basic principles of cell theory at the present stage can be formulated as follows:
| Basic provisions | Characteristic |
| 1. The cell is the basic structural unit of structure, development and life activity | All organisms are made up of cells. Multicellular organisms develop from a single fertilized egg. The vital processes of the body consist of the vital activity of individual cells |
| 2. The cells of all organisms are similar in chemical composition, structure, and functions | All cells contain organic compounds: carbohydrates, lipids, proteins, nucleic acids and inorganic substances: water and salts. All cells have a membrane, cytoplasm, nucleus and other cellular structures - organelles. All cells have the ability to grow, reproduce, respire, excrete, metabolize substances and energy, and have irritability. |
| 3. All new cells are formed from the division of original cells | The growth of the body occurs as a result of cell division; new cells are formed only when the original, maternal cells divide. In multicellular organisms, cells specialize in function and form tissues |
Conclusion: all organisms, except viruses, have cellular structure, similar chemical composition of cells, cell formation occurs in a similar way, which indicates the unity of origin of all living things.
The creation of the cell theory became the most important event in biology, one of the decisive proofs of the unity of living nature. Cell theory had a significant influence on the development of biology as a science and served as the foundation for the development of such disciplines as embryology, histology and physiology. It made it possible to create the basis for understanding life, the individual development of organisms, and to explain the evolutionary connection between them. The basic principles of cell theory have retained their significance today, although over more than one hundred and fifty years new information has been obtained about the structure, life activity and development of the cell. There are cells prokaryotic and eukaryotic. Organisms formed by prokaryotic cells are called prokaryotes, and organisms formed by eukaryotic cells - eukaryotes.
Classification of living things
The basis for this division of organisms into kingdoms is the methods of nutrition of these organisms and the structure of cells.
Chemical composition of the cell. The composition of organisms includes most of the chemical elements of the Periodic Table D.I. Mendeleev.
Macroelements – hydrogen, oxygen, carbon, nitrogen. This group also includes potassium, sodium, calcium, sulfur, phosphorus, magnesium, iron, chlorine (the content of these elements in the cell is tenths and hundredths of a percent). In total, macronutrients make up about 98%.
Microelements - zinc, copper, iodine, fluorine, molybdenum, boron, manganese, cobalt (the content of these elements in the cell is hundredths and thousandths of a percent).
Ultramicroelements - gold, platinum, mercury, cesium (the content of these elements in the cell does not exceed thousandths of a percent).
Microelements and ultramicroelements play important role in the body: iron is part of hemoglobin, iodine is a component of the thyroid hormone, a lack of selenium leads to cancer.
CHEMICAL ELEMENTS
Chemical elements form organic and inorganic substances:
Organic substances Inorganic substances
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Carbohydrates Proteins Fats ATP Nucleic Mineral Water
acid substances
Inorganic substances of the cell
Water– one of the most basic components of a living cell, making up on average 70-80% of the cell’s mass. In a cell, water is found in free (95%) and bound (5%) forms. In addition to the fact that it is part of their composition, for many organisms it is also a habitat.
The role of water in a cell is determined by its unique chemical and physical properties, associated mainly with the small size of 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 essential functions:
1. Water is a universal solvent for polar substances, such as salts, sugars, alcohols, acids, etc. Substances that are highly soluble in water are called hydrophilic.
2. Water molecules are involved in many chemical reactions, for example during the hydrolysis of polymers.
3. In the process of photosynthesis, water is an electron donor, a source of hydrogen ions and free oxygen.
4. Water does not dissolve non-polar substances and does not mix with them, since it cannot form hydrogen bonds with them. Substances that are insoluble in water are called hydrophobic.
5. Water has a high specific heat capacity. Breaking the hydrogen bonds that hold water molecules together requires the absorption of a large amount of energy. This property ensures the maintenance of the body's thermal balance during significant temperature changes in the environment.
6. Water has high thermal conductivity, which allows the body to maintain the same temperature throughout its entire volume.
7. Water is characterized by a high heat of vaporization, i.e., the ability of molecules to carry away a significant amount of heat while simultaneously cooling the body. Thanks to this property of water, which manifests itself during sweating in mammals, thermal shortness of breath in crocodiles and other animals, and transpiration in plants, overheating is prevented.
8. Water is characterized by extremely high surface tension. This property has great importance 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 on water or glide across its surface.
9. Water ensures the movement of substances in the cell and body, the absorption of substances and the removal of metabolic products.
10. In plants, water determines the turgor of cells, and in some animals it performs supporting functions, being a hydrostatic skeleton (round and annelids, echinoderms).
11. Water - component 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 moist environment on the mucous membranes of the respiratory tract). It is part of saliva, bile, tears, etc.
Properties, functions and meaning of water
Mineral salts. Salt molecules in aqueous solution break down into cations and anions. Highest value have cations (K+, Na+, Ca2+, Mg2+, NH4+) and anions (Cl-, H2P04 -, HP042-, HC03 -, NO3 2-, SO4 2-). Some ions are involved in the activation of enzymes and the creation of osmotic pressure in the cell , in the processes of muscle contraction, blood clotting, etc. A number of cations and anions are necessary for the synthesis of important organic substances (for example, phospholipids, ATP, nucleotides, hemoglobin, chlorophyll, etc.), as well as amino acids, being sources of nitrogen and sulfur atoms. Hydrochloric acid is part of gastric juice. Calcium and phosphorus salts are present in the bone tissue of animals and humans.
Organic substances. The basis of all organic compounds is carbon (C), which forms bonds with other atoms and their groups. As a result, complex chemical compounds, different in structure and function, are macromolecules (from the Greek macros - large).
Macromolecules consist of repeating low molecular weight compounds - monomers(from Greek monos - one).
Polymer(from Greek poly – many) – macromolecule formed by monomers.
In polymer molecules, monomers can be the same or different. Depending on what monomers are included in the polymers, polymers are divided into the following groups:
Polymers
Regular Irregular
A-A-A-A-A-A- - A-B-A-C- B-A-A-D- C- A-
A-S-D-A-S-D-A-S-D-
Polymers that make up living organisms are called biopolymers, the properties of which depend on the structure of their molecules, the number and variety of monomers. Biopolymers are universal, since they are built according to a single plan in all living organisms. The variety of properties of biopolymers is due to different combinations of monomers that form various options. The properties of biopolymers appear only in a living cell.
Carbohydrates or saccharides, - organic compounds, which include carbon, hydrogen and oxygen. They received the name “carbohydrates” because of their chemical composition: the general formula of most of them is Cn(H2O)n.
Composition and structure of carbohydrates
Monosaccharides – simple sugars having the general formula (CH2O)n, where n=3-9. Among the monosaccharides, there are trioses (3C), tetraoses (4C), pentoses (5C) - ribose, deoxyribose, hexoses (6C) - glucose, galactose. Monosaccharides are highly soluble in water and have a sweet taste. Fructose is part of honey and is found in fruits and green parts of plants. Glucose is found in fruits, blood, lymph, is the main source of energy, and is part of disaccharides and polysaccharides.
Disaccharides– substances formed as a result of the condensation of two molecules of monosaccharides with the loss of one molecule of water. In plants it is sucrose (C12H22O11) and maltose, in animals it is lactose. Sucrose is the main transport form of carbohydrates in plants. Lactose is formed in the mammary gland and is present in milk.
glucose + glucose = maltose;
glucose + galactose = lactose;
glucose + fructose = sucrose.
In their properties, disaccharides are close to monosaccharides. They dissolve well in water and have a sweet taste.
Polysaccharides- these are high-molecular carbohydrates formed by combining a large number of monosaccharide molecules. In plants - starch, cellulose (fiber), formula (C6H10O5)n; in animals - glycogen, chitin. Cellulose is the main supporting component of the cell wall in plants. Starch is the main reserve carbohydrate of plants. Glycogen is a reserve polysaccharide of animals (accumulates in the liver and muscles. Chitin is part of the integument of arthropods and ensures the strength of the integumentary structures of fungi.
Localization in the cell and body: cell wall, cellular inclusions, plant cell sap, integument of arthropods.
Functions of carbohydrates:
1) Energy. Carbohydrates are the main source of energy for organisms. During the oxidation process, 1 g of carbohydrates releases 17.6 kJ.
2) Structural. Plant cell walls are made of cellulose. The body covers of arthropods and the cell walls of fungi consist of chitin. Carbohydrates are part of organelles, DNA and RNA molecules.
3) Storage. This function is performed by starch in plants and glycogen in animals. They have the ability to accumulate in cells and be consumed as the need for energy arises.
4) Protective. The glands secrete secretions that contain carbohydrates. Secretions protect the walls of hollow organs (stomach, intestines) from mechanical damage and penetration of pathogenic bacteria.
Lipids- these are fat-like substances, most of which consist of fatty acids and trihydric alcohol; These are esters of higher fatty acids and the trihydric alcohol glycerol.
Fats are the simplest and most widespread lipids. Liquid fats are called oils. In animals, oils are found in milk, but are more often found in plants in seeds and fruits.
Composition and structure of lipids
Place of synthesis in the cell: on the membranes of the smooth endoplasmic reticulum.
Localization in the cell and body: cell membrane, cellular inclusions, subcutaneous fatty tissue and omentum.
Functions of lipids:
1) Energy. Lipids are an “energy depot”. When 1 g of lipids is oxidized to CO2 and H2O, 38.9 kJ is released, which is twice as much as carbohydrates and proteins.
2) Structural. Lipids take part in the construction of cell membranes and the formation of important biological compounds, for example, hormones and vitamins.
3) Storage. Plants tend to accumulate oils rather than fats. Soybean and sunflower seeds are rich in oils.
4) Protective and thermal insulation. Fats do not conduct heat well. They are deposited under the skin of animals; in some, such accumulations reach a thickness of up to 1 m, for example, in whales. The fat layer protects animals from hypothermia. Adipose tissue acts as a thermostat. In whales, in addition, it plays another role - it promotes buoyancy. Due to its low thermal conductivity, the layer of subcutaneous fat helps retain heat, which allows, for example, many animals to live in cold climates.
5) Lubricating and water-repellent. Wax covers the skin, wool, feathers, makes them more elastic and protects them from moisture. The leaves and fruits of many plants have a waxy coating. This layer protects the leaves during heavy rains from getting wet.
6) Regulatory. Many biologically active substances (sex hormones - testosterone in
men and progesterone in women), vitamins (A, D, E) are lipid compounds
7) Source of metabolic water. One of the products of fat oxidation is water, which
very important for some inhabitants of the desert animal world, for example, for camels.
The fat that these animals store in their humps is a source of water. Oxidation 100 g
fat yields approximately 105 g of water. Bears, marmots and
other animals hibernate as a result of fat oxidation.
8) In the myelin sheaths of the axons of nerve cells, lipids are insulators during the conduction of nerve impulses.
9) Wax is used by bees in the construction of honeycombs.
Lipids can form complexes with other biological molecules - proteins and sugars.
Proteins, or proteins (from the Greek protos - first) - the most numerous, diverse and paramount organic compounds. Proteins are macromolecules because they are large.
Chemical composition protein molecules: carbon, oxygen, hydrogen, nitrogen, sulfur, there may also be phosphorus, iron, zinc, copper.
Proteins are polymers consisting of repeating low molecular weight monomers. Amino acids are monomers of protein molecules. There are about 200 amino acids known to be found in living organisms, but only 20 of them are found in proteins. These are the so-called basic, or protein-forming amino acids. 20 amino acids provide protein diversity. In plants, all essential amino acids are synthesized from the primary products of photosynthesis. Humans and animals are not able to synthesize a number of amino acids and must receive them in finished form with food. Such amino acids are called essential. These include lysine, valine, leucine, isoleucine, threonine, phenylalanine, tryptophan, methionine, arginine and histidine (10 in total).
Amino acid structure:
A covalent bond is formed between the amino group of one amino acid and the carboxyl group of another amino acid, which is called peptide bond, and the protein molecule is polypeptide.
In solution, amino acids can act as both acids and bases, i.e. they are amphoteric compounds. The carboxyl group -COOH is capable of donating a proton, functioning as an acid, and the amino group - NH2 - can accept a proton, thus exhibiting the properties of a base.
Structure of proteins. Each protein in a certain environment is characterized by a special spatial structure. When characterizing the spatial (three-dimensional) structure, four levels of organization of protein molecules are distinguished.
Levels of protein structural organization: a - primary structure - amino acid sequence of the protein; b - secondary structure - the polypeptide chain is twisted in the form of a spiral; c - tertiary structure of the protein; d - quaternary structure of hemoglobin.
Place of protein synthesis in the cell: on ribosomes.
Localization of proteins in the cell and body: present in all organelles and the cytoplasmic matrix.
Spatial structure of the protein:
Primary structure protein - a sequence of amino acids connected to each other by peptide bonds to form a polypeptide chain. All properties and functions of proteins depend on the primary structure. Replacement of a single amino acid in the composition of protein molecules or disruption of their arrangement usually entails a change in the function of the protein.
Secondary structure The protein molecule is achieved by its spiralization: the polypeptide chain, consisting of sequentially connected amino acids, is twisted into a spiral, weak hydrogen bonds are formed between - CO - and - NH - groups.
During education tertiary structure the spiralized protein molecule folds several times more, forming a ball - a globule. The strength of the tertiary structure is determined by various bonds, for example, disulfide bonds (-S-S-), ionic, hydrogen, hydrophobic interactions.
Quaternary structure is a compound consisting of several protein molecules with a tertiary structure. Chemical bonds- ionic, hydrogen, hydrophobic interaction.
And so, the primary structure is a linear structure, in the form of a polypeptide chain; secondary – helical, due to hydrogen bonds; tertiary – globular; quaternary - a combination of several protein molecules with a tertiary structure.
Protein property - denaturation- violation natural structure protein, which is reversible if the primary structure is not destroyed, and irreversible if the primary structure is destroyed.
Impact of environmental factors
(temperature, chemicals, radiation, etc.)
Protein denaturation (destruction of structures)
Renaturation – full recovery protein structure.
Under the influence of various chemical and physical factors (treatment with alcohol, acetone, acids, alkalis, high temperature, irradiation, high pressure etc.) there is a change in the secondary, tertiary and quaternary structures of the protein due to the rupture of hydrogen and ionic bonds. The process of disrupting the natural structure of a protein is called denaturation. In this case, there is a decrease in protein solubility, a change in the shape and size of molecules, loss of enzymatic activity, etc. The denaturation process can be complete or partial. In some cases, the transition to normal conditions environment is accompanied by spontaneous restoration of the natural structure of the protein. This process is called renaturation.
Simple and complex proteins. Based on their chemical composition, proteins are divided into simple and complex. Simple proteins include proteins consisting only of amino acids, and complex proteins include proteins containing a protein part and a non-protein part - metal ions, phosphoric acid residues, carbohydrates, lipids, etc.
Functions of proteins:
1) Enzymatic, or catalytic. Catalysts are substances that speed up chemical reactions. Enzymes- These are catalysts for biochemical reactions. Enzymes speed up reactions in the body tens and hundreds of thousands of times. They are highly specific because each enzyme catalyzes only a specific reaction.
Enzymes = Biocatalysts (accelerators of chemical reactions occurring in cells)
2) Structural. Proteins are part of all cell membranes and organelles (for example, in combination with RNA, protein forms ribosomes).
3) Energy. When 1 g of proteins breaks down into final products (CO2, H2O and nitrogen-containing substances), 17.6 kJ is released.
4) Storage. This function is performed by proteins - food sources (egg white - albumin,
milk protein – casein, endosperm and egg cells).
5) Protective. All living cells and organisms have defense systems. In humans and animals, this is immune defense. Antibodies are formed in lymphocytes - protective proteins that neutralize foreign bodies. Another example of a protective function is the coagulation of the fibrinogen protein in the blood, which leads to the formation of a blood clot - a thrombus that clogs the vessel and stops bleeding. Mechanical protection is provided by horny formations - hair, horns, hooves. The composition of these formations includes proteins. Plants also form protective proteins, for example, alkaloids, thanks to which plant covers become stronger and more resilient.
6) Regulatory. Many proteins hormones regulating physiological processes (insulin and glucagon are of protein nature). Pancreatic cells produce the hormone insulin, which regulates blood glucose levels.
Pancreas
Hormone insulin
Glucose (in blood) à Glycogen (in liver cells)
7) Transport. The function of transport proteins is to attach chemical elements or biologically active substances and transport them to tissues and organs.
Hemoglobin (found in red blood cells)
Hemoglobin + oxygen Hemoglobin + carbon dioxide
8) Motor. Contractile proteins are involved in all types of movement that cells and organisms are capable of. Examples: the movement of flagella and cilia in the simplest unicellular animals, muscle contraction in multicellular animals (the proteins myosin and actin ensure the contraction of muscle cells), the movement of leaves in plants.
9) Signal. Proteins embedded in the cell membrane receive signals from
external environment and transmission of information into the cell. Such protein molecules able
change its tertiary structure in response to the actions of environmental factors.
10) Toxic(toxins that provide protection from enemies and killing prey).
| Protein functions | Characteristic |
| 1. Structural | Proteins are part of cell membranes and organelles |
| 2. Energy | When 1 g of proteins is oxidized, 17.6 kJ is released |
| 3. Storage | Proteins – reserve nutritional and energy material |
| 4. Catalytic, enzymatic | Proteins are enzymes that speed up chemical reactions |
| 5. Regulatory | Many proteins are hormones that regulate physiological processes. |
| 6. Transport | Transfer of various substances (hemoglobin + oxygen) |
| 7. Motor | Contractile proteins provide movement (chromosomes to the cell poles) |
| 8. Protective | Protect the body from foreign bodies |
| 9. Signal | Receive signals from the external environment and transmit information into the cell |
| 10. Toxic | Toxins provide protection from enemies and killing prey |
Proteins are rarely used as a source of energy because they perform a number of other important functions. Proteins are typically used when sources such as carbohydrates and fats are depleted. Carbohydrates and fats are stored; when food lacks any organic compound, it is possible for the body to convert some organic compounds into others: proteins into fats and carbohydrates, carbohydrates and fats into each other. But carbohydrates and fats cannot be converted into proteins.
All chemical compounds in a cell can be divided into organic and inorganic (Table 1).
Water (N 2 ABOUT)
The unique properties of water are determined by the structural features of its molecules. Water molecules are connected by hydrogen bonds, which provides the property: universal solvent. Water molecules are able to “stick” to each other - this explains capillary property(the ability to rise up through thin tubes, pores (vessels of plants).
Water is included body fluids: - intercellular substance (tissue fluid); - blood (blood plasma); - lymph (lymph plasma). Performs a lubricating role: in the cardiac sac - pericardial fluid; in the pleural cavity - pleural fluid; in the joints (synovial fluid).
Water has two forms: free - makes up 95% of all water and bound - 4%.
Functions of water:
Universal solvent
Transport
Thermoregulatory (maintains thermal balance of the cell and the body as a whole due to high heat capacity and thermal conductivity)
Osmoregulatory (affects a number of physiological properties: elasticity, turgor)
Participates in chemical reactions (participates in metabolic processes, is necessary for the oxidation and hydrolysis of proteins, carbohydrates, fats, serves as a source of H + during photosynthesis).
The environment in which biochemical reactions take place.
Mineral salts and acids
Most mineral salts are in a dissociated state in the form of ions. The most important cations of these are K +, Na +, Mg 2+, NH 4 +; anions CI -, HPO 4 2-, HCO 3 -, H 2 PO 4 -, NO 3 -. The concentration of ions in the cell and its environment is not the same. For example, the potassium content in cells is tens of times higher than in the intercellular space. On the contrary, there are fewer sodium cations in the cell than outside it. A decrease in the concentration of K ions in a cell leads to a decrease in water in it, the amount of which increases in the intercellular space, the more, the higher the concentration of Na + in the intercellular fluid. A decrease in sodium cations in the intercellular space leads to a decrease in its water content. Uneven distribution of potassium and sodium ions from the outside and inside membranes of nerve and muscle cells provide the possibility of the occurrence and propagation of electrical impulses. (pH=7.2).
Functions of mineral salts:
Buffering of the intercellular fluid (acid-base balance of plasma, due to maintaining a certain concentration of hydrogen ions, providing a slightly alkaline pH = 7.2 with the participation of the phosphate and bicarbonate systems)
Constant osmotic pressure (7.6 atm.)
Enzyme activation.
Source building material for the synthesis of organic compounds (for example, the residue PO 4 3- forms high-energy bonds of ATP, affects the physiological activity of proteins and enzymes; Cl - in the process of digestion).
Provide irritability (K +, Na +, Ca +2).
Provide cell adhesion multicellular organism(Ca 2+).
Insoluble salts Ca 3 (PO 4) 2 are part of the intercellular substance of bone tissue and mollusk shells, providing protection and strength.
