From inorganic substances cells water makes up about 65% of its mass: in young fast-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, and is involved in most chemical reactions, movement of substances, thermoregulation, formation of cellular structures, determines the volume and elasticity of the cell. Most substances enter and exit the body 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, and nucleic acids.
Proteins are the main and most complex substances of any cell. The size of a protein molecule is hundreds and thousands of times larger than that of non-protein molecules. organic 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 body, catalysts (enzyme proteins accelerate chemical reactions), transport (blood hemoglobin delivers oxygen and nutrients to cells and carries away carbon dioxide and decomposition products). Proteins perform protective function, energy. Carbohydrates are organic substances consisting 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 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 of biological membranes. Lipids perform an energy function and contain fat-soluble vitamins. Nucleic acids - (from Latin word“nucleus” - nucleus) - are formed in the nucleus of the cell. They come in 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.
Cell
From the point of view of the concept of living systems according to A. Lehninger.
A living cell is an isothermal system of organic molecules capable of self-regulation and self-reproduction, extracting energy and resources from the environment.
A large number of sequential reactions take place in a cell, the speed of which is regulated by the cell itself.
The cell maintains itself in a stationary dynamic state, far from equilibrium with the environment.
Cells function on the principle of minimal consumption of components and processes.
That. A cell is an elementary living open system capable of independent existence, reproduction and development. It is the elementary structural and functional unit of all living organisms.
Chemical composition cells.
Of the 110 elements of Mendeleev’s periodic table, 86 were found to be constantly present in the human body. 25 of them are necessary for normal life, 18 of them are absolutely necessary, and 7 are useful. In accordance with the percentage content in the cell, chemical elements are divided into three groups:
Macroelements The main elements (organogens) are hydrogen, carbon, oxygen, nitrogen. Their concentration: 98 – 99.9%. They are universal components of organic cell compounds.
Microelements - sodium, magnesium, phosphorus, sulfur, chlorine, potassium, calcium, iron. Their concentration is 0.1%.
Ultramicroelements - boron, silicon, vanadium, manganese, cobalt, copper, zinc, molybdenum, selenium, iodine, bromine, fluorine. They affect metabolism. Their absence is the cause of diseases (zinc - diabetes mellitus, iodine - endemic goiter, iron - pernicious anemia, etc.).
Modern medicine knows facts about negative interactions between vitamins and minerals:
Zinc reduces copper absorption and competes with iron and calcium for absorption; (and zinc deficiency causes a weakening of the immune system and a number of pathological conditions on the part of the endocrine glands).
Calcium and iron reduce the absorption of manganese;
Vitamin E does not combine well with iron, and vitamin C does not combine well with B vitamins.
Positive interaction:
Vitamin E and selenium, as well as calcium and vitamin K, act synergistically;
Vitamin D is necessary for the absorption of calcium;
Copper promotes the absorption and increases the efficiency of iron use in the body.
Inorganic components of the cell.
Water– the most important component cells, the universal dispersion medium of living matter. Active cells of terrestrial organisms consist of 60–95% water. In resting cells and tissues (seeds, spores) there is 10 - 20% water. Water in the cell is in two forms - free and bound to cellular colloids. Free water is the solvent and dispersion medium of the colloidal system of protoplasm. Its 95%. Bound water (4–5%) of all cell water forms weak hydrogen and hydroxyl bonds with proteins.
Properties of water:
Water is a natural solvent for mineral ions and other substances.
Water is the dispersive phase of the colloidal system of protoplasm.
Water is the medium for cell metabolic reactions, because physiological processes occur in an exclusively aquatic environment. Provides reactions of hydrolysis, hydration, swelling.
Participates in many enzymatic reactions cells and is formed during metabolism.
Water is a source of hydrogen ions during photosynthesis in plants.
Biological significance of water:
Most biochemical reactions occur only in aqueous solution; many substances enter and exit cells in dissolved form. This characterizes the transport function of water.
Water provides hydrolysis reactions - the breakdown of proteins, fats, carbohydrates under the influence of water.
Due to the high heat of evaporation, the body is cooled. For example, sweating in humans or transpiration in plants.
The high heat capacity and thermal conductivity of water contributes to the uniform distribution of heat in the cell.
Due to the forces of adhesion (water - soil) and cohesion (water - water), water has the property of capillarity.
The incompressibility of water determines the stressed state of cell walls (turgor) and the hydrostatic skeleton in roundworms.
The chemical composition of plant and animal cells is very similar, which indicates the unity of their origin. More than 80 were found in cells chemical elements.
The chemical elements present in the cell are divided into 3 large groups: macronutrients, mesoelements, microelements.
Macroelements include carbon, oxygen, hydrogen and nitrogen. Mesoelements- this is sulfur, phosphorus, potassium, calcium, iron. Microelements - zinc, iodine, copper, manganese and others.
Biologically important chemical elements of the cell:
Nitrogen - structural component of proteins and NK.
Hydrogen- is part of water and all biological compounds.
Magnesium- activates the work of many enzymes; structural component of chlorophyll.
Calcium- the main component of bones and teeth.
Iron- is included in hemoglobin.
Iodine- is part of the thyroid hormone.
Cell substances are divided into organic(proteins, nucleic acids, lipids, carbohydrates, ATP) and inorganic(water and mineral salts).
Water makes up up to 80% of the cell mass, plays important role :
water in the cell is a solvent
· transports nutrients;
· water is removed from the body harmful substances;
· high heat capacity of water;
· Evaporation of water helps cool animals and plants.
· gives the cell elasticity.
Minerals:
· participate in maintaining homeostasis by regulating the flow of water into the cell;
· potassium and sodium ensure the transfer of substances across the membrane and are involved in the occurrence and conduction of nerve impulses.
· mineral salts, primarily calcium phosphates and carbonates, impart hardness to bone tissue.
Solve a problem on human blood genetics
Proteins, their role in the body
Protein- organic substances found in all cells, which consist of monomers.
Protein- high molecular weight non-periodic polymer.
Monomer is amino acid (20).
Amino acids contain an amino group, a carboxyl group and a radical. Amino acids are connected to each other to form a peptide bond. Proteins are extremely diverse; for example, there are over 10 million of them in the human body.
Protein diversity depends on:
1. different sequence of AKs
2. depending on size
3. from the composition
Protein structures
Primary structure of protein - a sequence of amino acids connected by a peptide bond (linear structure).
Protein secondary structure - spiral structure.
Protein tertiary structure- globule (glomerular structure).
Quaternary protein structure- consists of several globules. Characteristic of hemoglobin and chlorophyll.
Properties of proteins
1. Complementarity: the ability of a protein to fit some other substance in shape like a key to a lock.
2. Denaturation: violation of the natural structure of the protein (temperature, acidity, salinity, addition of other substances, etc.). Examples of denaturation: a change in the properties of protein when boiling eggs, the transition of protein from a liquid to a solid state.
3. Renaturation - restoration of the protein structure if the primary structure has not been damaged.
Protein functions
1. Construction: formation of all cell membranes
2. Catalytic: proteins are catalysts; speed up chemical reactions
3. Motor: actin and myosin are part of muscle fibers.
4. Transport: transfer of substances to various tissues and body organs (hemoglobin is a protein that is part of red blood cells)
5. Protective: antibodies, fibrinogen, thrombin - proteins involved in the development of immunity and blood clotting;
6. Energy: participate in plastic exchange reactions to build new proteins.
7. Regulatory: the role of the hormone insulin in the regulation of blood sugar.
8. Storage: accumulation of proteins in the body as reserve nutrients, for example in eggs, milk, plant seeds.
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 | |
|
Water (accounts for 70-80% of the cell mass) |
Mineral salts (make up 1-1.5% of the total cell mass) |
|
|
Water is an essential component of the contents of a living cell. Water gives the cell elasticity and volume, ensures consistency of composition, participates in chemical reactions and in the construction of organic molecules, and makes possible the occurrence of all vital processes of the cell. Water is a solvent for chemicals that move into and out of the cell.
Water(hydrogen oxide, H 2 O) is a transparent liquid that is colorless (in small volumes), odor and taste. IN natural conditions contains dissolved substances (salts, gases). Water is of key importance in the life of cells and living organisms, in the formation of climate and weather.
The amount of water in the cell ranges from 60 to 95% of the total mass. The role of water in a cell is determined by its unique chemical and physical properties associated with the small size of molecules, their polarity and 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 chemical reactions in the cell take place in aqueous solutions.
- Non-polar substances are insoluble in water (hydrogen bonds do not form). Being attracted to each other, hydrophobic substances in the presence of water form various complexes (for example, biological membranes).
- High specific heat water (i.e. absorption large quantity energy to break hydrogen bonds) ensures the maintenance of the body’s thermal balance during changes in ambient temperature.
- The high heat of vaporization (the ability of molecules to carry away a significant amount of heat when cooling the body) prevents overheating of the body.
- High surface tension ensures the movement of solutions through tissues.
- Water ensures the removal 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, sperm, synovial and pleural fluids, etc.).
The water molecule has an angular shape: the hydrogen atoms form an angle of approximately 104.5° with respect to oxygen.
Due to the high electronegativity of the oxygen atom, the O–H bond is polar. The hydrogen atoms carry a partial positive charge, and the oxygen atoms carry a partial negative charge.
A dipole creates a magnetic field around itself at large distances compared to its size.
When water evaporates, breaking hydrogen bonds requires a lot of energy.
| Water content in various 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 |
| Woody parts of plants | from 40 to 80 | Human heart | 70 |
| Dry seeds | from 5 to 9 | ||
Inorganic substances in the cell, except water, are represented by 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.
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. More often these are calcium salts. Their shape in plant cells can be different: needles, rhombuses, crystals - single or fused together (drusen).
Salt molecules in an aqueous solution break down into cations and anions. The most important are cations (K +, Na +, Ca 2+, Mg +, NH 4 +) and anions (Cl -, H 2 P0 4 -, HP0 4 2-, HC0 3 -, NO 3 -, SO 4 2 -).
The concentration of various ions is not the same in different parts of the cell, as well as in the cell and environment. The concentration of sodium ions is always higher outside the cell, and the concentration of potassium and magnesium ions is always higher inside the cell. The difference between the amount of cations and anions inside the cell and on its surface ensures the active transfer of substances across the membrane.
The buffering properties of the cytoplasm—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—depend on the concentration of salts inside the cell.
Phosphoric acid anions create a phosphate buffer system that maintains the pH of the body's intracellular environment at 6.9.
Carbonic acid and its anions form a bicarbonate buffer system that maintains the pH of the extracellular environment (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 clotting, etc. A number of cations and anions are necessary for the synthesis of important organic substances.
Inorganic substances that make up the cell
The purpose of the lesson: study the chemical composition of the cell, identify the role of inorganic substances.
Lesson objectives:
educational: show the variety of chemical elements and compounds that make up living organisms, their significance in the process of life;
developing: continue to develop skills and abilities independent work with a textbook, the ability to highlight the main points, formulate conclusions;
educational: cultivate a responsible attitude towards completing assigned tasks.
Equipment: multimedia projector, presentation, handouts.
Lesson Plan
I. Organizational moment.
Greetings; – preparing the audience for work; – availability of students.
II. Motivation for learning activities.
– Here is a set of words: copper, proteins, iron, carbohydrates, fats, vitamins, magnesium, gold, sulfur, calcium, phosphorus.
– What two groups can these words be divided into according to their meaning? Explain your answer. (Organic and inorganic; chemical substances and chemical elements).
– How many of you can name the role of certain substances or elements in the life of living organisms?
– Set the goal and objectives of our lesson, based on the title of the topic.
III. Presentation of new material.
Presentation. The presentation includes 3 lessons on this topic. We start working with the key second slide: follow the hyperlink to the desired lesson.
3rd slide: conversation according to the scheme “Content of chemical elements in the human body.”:
– The cell contains about 80 different chemical elements that are found in inanimate objects. What does this mean? (about the commonality of living and inanimate nature). 27 elements perform specific functions, the rest enter the body with food, water and air.
– Name what chemical elements and in what quantities are contained in the human body?
– All chemical compounds found in living organisms are divided into groups.
– Using the table, make a diagram “The main groups of chemical elements in nature” (see table “Elements that make up the cells of living organisms”, see Table 1 ). Oxygen, hydrogen, carbon, nitrogen, sulfur and phosphorus are necessary components of biological polymer molecules (proteins, nucleic acids); they are often called bioelements.
Scheme
Slide 5: Start filling out the table - a reference summary in your notebook (this table will be supplemented in subsequent lessons, see table 2 ).
- Of all chemical compounds contained in living organisms, water makes up 75–85% of body weight.
– Why is this amount of water needed? What functions does water perform in a living organism?
– You already know that structure and functions are interconnected. Let's take a closer look at the structure of the water molecule to find out why water has these properties. As you explain, you fill out a supporting summary in your notebook (see slide 5).
Slides 6 – 7 demonstrate the structural features of the water molecule and its properties.
– Among the inorganic compounds that make up organisms, highest value have salts of mineral acids and corresponding cations and anions. Although the need of humans and animals for minerals is expressed in tens and even thousandths of a gram, the absence of any biologically important elements leads to serious illnesses.
– Fill out the table, column “Mineral salts”, using the textbook material pp. 104 – 107. ( Slide 8 Click the hyperlink to check the completed work).
– Give examples proving the role of mineral salts in the life of living organisms.
IV. Consolidating new material:
several students (how many computers are in the class) perform interactive test 1 “Inorganic substances of cells”;
the rest do tasks for training thinking and the ability to draw conclusions(Handout) :
There is a certain connection between the first two terms. There is the same connection between the fourth and one of the concepts below. Find it:
1. Iodine: thyroid gland = fluoride: ___________________
a) Pancreas b) tooth enamel V) nucleic acid d) adrenal glands
2. Iron: hemoglobin = __________: chlorophyll:
a) cobalt b) copper c) iodine d) magnesium
3. Execute digital dictation “Molecules”. 1. Hydrogen bonds are the weakest bonds in a molecule (1). 2. Structure and composition are one and the same (0). 3. Composition always determines structure (0). 4. The composition and structure of a molecule determine its properties (1). 5. The polarity of water molecules explains its ability to slowly heat up and cool down (0). 6. The oxygen atom in a water molecule carries a positive charge. (0)
V. Lesson summary.
– Have you fulfilled the goals and objectives of the lesson? What new things did you discover in this lesson?
Literature:
Biology. 9th grade: lesson plans based on the textbook by S.G. Mamontov, V.B. Zakharova, N.I. Sonina / author. – comp. M.M.Gumenyuk. Volgograd: Teacher, 2006.
Lerner G.I. General biology. Lesson tests and assignments. 10 – 11 grades/ – M.: Aquarium, 1998.
Mamontov S.G., Zakharov V.B., Sonin N.I. Biology. General patterns. 9th grade: Textbook. for general education textbook establishments. – M.: Bustard, 2000.
CD Digital Set educational resources to the textbook Teremov A.V., Petrosova R.A., Nikishov A.I. Biology. General patterns of life: 9th grade. humanit ed. VLADOS Center, 2003. Physikon LLC, 2007.