86 found in the human body chemical elements, included in the Periodic Table of Chemical Elements D.I. Mendeleev. These elements are conventionally divided into four groups:

• macroelements - elements that make up the bulk of the cell (approximately 98-99% in terms of dry weight), including carbon (C), hydrogen (H), oxygen (O) and nitrogen (N);
• elements, the content of which in the cell, calculated on a dry weight basis, is about 1.9%. These are potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), sulfur (S), phosphorus (P), chlorine (Cl) and iron (Fe);
• elements whose content in a cell, calculated on a dry weight basis, is less than 0.01% are microelements. These are zinc (Zn), copper (Cu), fluorine (F), iodine (I), cobalt (Co), molybdenum (Mo), etc.
• elements whose content in a cell, calculated on a dry weight basis, is less than 0.00001% - ultramicroelements: gold (Au), uranium (U), radium (Ra), etc.

The role of chemical elements in the cells of living organisms

Each element that makes up a living organism is responsible for performing a specific function (Table 1).

Table 1. The role of chemical elements in the cells of living organisms.

A deficiency of any element can lead to illness and even death of the body, since each element plays a specific role. Macroelements of the first group form the basis of biopolymers - proteins, carbohydrates, nucleic acids, as well as lipids, without which life is impossible. Sulfur is part of some proteins, phosphorus is part of nucleic acids, iron is part of hemoglobin, and magnesium is part of chlorophyll. Calcium plays an important role in metabolism

Some of the chemical elements contained in the cell are part of inorganic substances - mineral salts and water. Mineral salts are found in the cell, as a rule, in the form of cations (K +, Na +, Ca 2+, Mg 2+) and anions (HPO 4 2-, H 2 PO 4 -, CI -, HCO 3 -), the ratio which determines the acidity of the environment, which is important for the life of cells, the slightly alkaline environment of many cells and its pH almost does not change, because a certain ratio of cations and anions is constantly maintained in it.

Water plays big role V chemical reactions flowing in the cell in aqueous solutions. It dissolves metabolic products that the body does not need and thereby promotes their removal from the body. The high water content in the cell gives it elasticity. Water facilitates the movement of various substances within a cell or from cell to cell.

Examples of problem solving

EXAMPLE 1

EXAMPLE 2

IN modern conditions One of the most pressing problems in teaching chemistry is ensuring the practical orientation of subject knowledge. This means the need to clarify the close relationship between the theoretical principles being studied and the practice of life, to demonstrate the applied nature of chemical knowledge. Students begin to study chemistry with interest. In order to maintain the cognitive interest of students, it is necessary to convince them of the effectiveness of chemical knowledge and to form a personal need to master the educational material.

The purpose of this lesson: broaden students' horizons and increase cognitive interest in studying the subject, form ideological concepts about the knowability of nature. This lesson is proposed to be taught in 8th grade after studying the chemical elements of the Periodic Table, when the children already have an idea of ​​their diversity.

PROGRESS OF THE LESSON

Teacher:

There is nothing else in nature
Neither here nor there, in the depths of space:
Everything – from small grains of sand to planets –
It consists of uniform elements.
Like a formula, like a work schedule,
The structure of the Mendeleev system is strict.
The living world is happening around you,
Enter it, inhale it, touch it with your hands.

The lesson begins with a theatrical skit “Who is most important in the table?” (cm. Appendix 1).

Teacher: The human body contains 81 chemical elements out of 92 found in nature. The human body is a complex chemical laboratory. It’s hard to imagine that our daily well-being, mood and even appetite can depend on minerals. Without them, vitamins are useless, the synthesis and breakdown of proteins, fats and carbohydrates is impossible.

On the students’ desks are tables “Biological role of chemical elements” (see. Appendix 2). Time is given to get to know her. The teacher and students analyze the table by asking questions.

Teacher: The basis of life is made up of six elements of the first three periods (H, C, N, O, P, S), which account for 98% of the mass of living matter (the remaining elements of the periodic table make up no more than 2%).
Three main characteristics of nutrients (H, C, N, O, P, S):

• small atomic size,
• small relative atomic mass,
• the ability to form strong covalent bonds.

Students are given texts (see Appendix 3). Assignment: read the text carefully; identify elements necessary for life and elements dangerous to living organisms; find them in the Periodic Table and explain their role.
After completing the assignment, several students analyze different texts.

Teacher: Analogue elements in the natural environment enter into competition and can be interchanged in living organisms, negatively affecting them.
Replacing sodium and potassium in animals and humans with lithium causes disorders of the nervous system, since in this case the cells do not conduct nerve impulses. Such disorders lead to schizophrenia.
Thallium, a biological competitor of potassium, replaces it in cell walls and affects the central and peripheral nervous system, gastrointestinal tract and kidneys.
Selenium can replace sulfur in proteins. This is the only element that, when present in high levels in plants, can cause sudden death in animals and humans who eat them.
When calcium is deficient in the soil, the body replaces it with strontium, which gradually disrupts the normal structure of the skeleton. Particularly dangerous is the replacement of calcium with strontium-90, which accumulates in huge quantities at sites of nuclear explosions (during nuclear weapons testing) or during accidents at nuclear power plants. This radionuclide destroys bone marrow.
Cadmium competes with zinc. This element reduces the activity of digestive enzymes, disrupts the formation of glycogen in the liver, causes skeletal deformation, inhibits bone growth, and also causes severe pain in the lower back and leg muscles, and bone fragility (for example, broken ribs when coughing). Other negative consequences are lung and rectal cancer, pancreatic dysfunction. Kidney damage, decreased levels of iron, calcium, and phosphorus in the blood. This element inhibits self-purification processes in aquatic and terrestrial plants (for example, a 20-30-fold increase in cadmium in tobacco leaves is noted).
Halogens can be very easily interchanged in the body. Excess fluorine in the environment (fluoridated water, soil contamination with fluorine compounds around an aluminum production plant and other reasons) prevents the entry of iodine into the human body. In this regard, diseases of the thyroid gland and the endocrine system as a whole occur.

Student messages prepared in advance.

1st student:

Medieval alchemists considered gold to be perfection, and other metals to be an error in the act of creation, and, as is known, they made great efforts to eliminate this error. The idea of ​​​​introducing gold into medical practice is attributed to Paracelsus, who declared that the goal of chemistry should not be the transformation of all metals into gold, but the preparation of medicines. Medicines made from gold and its compounds have been tried to treat many diseases. They were used to treat leprosy, lupus, and tuberculosis. In people sensitive to gold, it could cause a disturbance in the blood composition, a reaction in the kidneys, liver, affect mood, teeth and hair growth. Gold ensures the functioning of the nervous system. It is found in corn. And the fortress blood vessels depends on germanium. The only food product containing germanium is garlic.

2nd student:

In the human body, the largest amount of copper is found in the brain and liver, and this circumstance alone indicates its importance in life. It has been found that during pain, the concentration of copper in the blood and cerebrospinal fluid increases. In Syria and Egypt, newborns are given copper bracelets to prevent rickets and epilepsy.

3rd student:

ALUMINUM

Aluminum cookware is called the poor man's cookware, as this metal contributes to the development of senile atherosclerosis. When cooking food in such containers, aluminum partially passes into the body, where it accumulates.

4th student:

• What element is contained in apples? (Iron.)
• What is it biological role? (The body contains 3 g of iron, of which 2 g is in the blood. Iron is part of hemoglobin. Insufficient iron content leads to headaches and fatigue.)

Then students conduct a laboratory experiment, the purpose of which is to experimentally prove the effect of salts of certain metals on protein. They mix the protein with solutions of alkali and copper sulfate and observe the formation of a purple precipitate. They conclude that the protein is destroyed.

5th student:

Man is also nature.
He is also a sunset and a sunrise.
And there are four seasons in it.
And there is a special way of music in it.

AND special sacrament colors,
Sometimes with cruel, sometimes with kind fire.
The man is winter. Or summer.
Or autumn. With thunder and rain.

It contained everything – miles and time.
And he became blind from atomic storms.
Man is both soil and seed.
And a weed in the middle of the field. And bread.

And what is the weather like there?
How much loneliness is there in him? Meeting?
Man is also nature...
So let's save nature!

(S. Ostrovoy)

To consolidate the knowledge acquired in the lesson, the “Smile” test is carried out (see. Appendix 4).
Next, you are asked to fill out the crossword puzzle “Chemical Kaleidoscope” (see. Appendix 5).
The teacher sums up the lesson, noting the most active students.

6th student:

Change, change!
The call is ringing.
It's finally finished
Annoying lesson!

Pulling sulfur by the pigtail,
Magnesium ran past.
The iodine from the class has evaporated,
It was as if I had never been there at all.

Fluoride accidentally set the water on fire
Chlorine ate someone else's book.
Carbon suddenly with hydrogen
Managed to become invisible.

Potassium and bromine are fighting in the corner:
They won't share the electron.
Oxygen is a naughty boy in the woods
He galloped past on horseback.

Literature used:

1. O.V. Baidalina On the applied aspect of chemical knowledge. “Chemistry at school” No. 5, 2005
2. Chemistry and ecology in school course. “First of September” No. 14, 2005
3. I. N. Pimenov, A. V. Pimenov“Lectures on general biology”, training manual, Saratov, OJSC Publishing House “Lyceum”, 2003
4. About chemistry in verse, Who is most important in the table? “First of September”, No. 15, 2005
5. Metals in the human body. “Chemistry at school”, No. 6, 2005.
6. Crossword “Chemical Kaleidoscope”. “First of September”, No. 1 4, 2005
7. “I'm going to chemistry class.” Book for teachers. M. “First of September”, 2002, p. 12.

1. Give definitions of concepts.
Element- a collection of atoms with the same nuclear charge and the number of protons, coinciding with the serial (atomic) number in the periodic table.
Microelement - an element that is found in very low concentrations in the body.
Macronutrient - an element that is found in high concentrations in the body.
Bioelement- a chemical element involved in the life of a cell and forms the basis of biomolecules.
Elemental composition of the cell - percentage of chemical elements in the cell.

2. What is one of the proofs of the commonality of living and inanimate nature?
Unity of chemical composition. There are no elements characteristic only of inanimate nature.

3. Fill out the table.

ELEMENTAL COMPOSITION OF A CELL

4. Give examples of organic substances whose molecules consist of three, four and five macroelements.
3 elements: carbohydrates and lipids.
4 elements: proteins.
5 elements: nucleic acids, proteins.

5. Fill out the table.

BIOLOGICAL ROLE OF ELEMENTS

6. Study the section “Role” in § 2.2 external factors in the formation of the chemical composition of living nature” and answer the question: “What are biochemical endemics, and what are the reasons for their origin?”
Biochemical endemics are diseases of plants, animals and humans caused by a sharp deficiency or excess of any element in a certain area.

7. What diseases do you know associated with a lack of microelements?
Iodine deficiency - endemic goiter. A decrease in the synthesis of thyroxine and, as a result, proliferation of thyroid tissue.
Lack of iron – iron deficiency anemia.

8. Remember on what basis chemical elements are divided into macro-, micro- and ultra-microelements. Propose your own alternative classification of chemical elements (for example, by functions in a living cell).
Micro-, macro- and ultra-microelements are divided according to their percentage in the cell. In addition, it is possible to classify elements by functions that regulate activities certain systems organs: nervous, muscular, circulatory and cardiovascular, digestive, etc.

9. Choose the correct answer.
Test 1.
What chemical elements form most organic substances?
2) C, O, H, N;

Test 2.
Does not apply to macroelements:
4) manganese.

Test 3.
Living organisms need nitrogen because it serves:
1) a constituent component of proteins and nucleic acids; 10. Determine the characteristic by which all of the following elements, except one, are combined into one group. Emphasize this “extra” element.
Oxygen, hydrogen, sulfur, iron, carbon, phosphorus, nitrogen. Contains only DNA. And the rest are all in proteins.

11. Explain the origin and general meaning words (terms), based on the meaning of the roots that make up them.

12. Choose a term and explain how it is modern meaning corresponds to the original meaning of its roots.
Selected term– organogen.
Correspondence: the term, in principle, corresponds to its original meaning, but today there is more precise definition. Previously, the meaning was such that the elements took part only in the construction of tissues and organ cells. Now it is clear that biologically important elements not only form chemical molecules in cells, etc., but also regulate all processes in cells, tissues and organs. They are part of hormones, vitamins, enzymes and other biomolecules.

13. Formulate and write down the main ideas of § 2.2.
The elemental composition of a cell is the percentage of chemical elements in the cell. Cell elements are usually classified depending on their percentage, for micro-, macro- and ultramicroelements. Those elements that participate in the life of the cell, form the basis of biomolecules, are called bioelements.
Macroelements include: C N H O. They are the main components of all organic compounds in a cage. In addition, P S K Ca Na Fe Cl Mg - are part of all the most important biomolecules. Without them, the body cannot function. Their deficiency leads to death.
For microelements: Al Cu Mn Zn Mo Co Ni I Se Br F B, etc. They are also necessary for the normal functioning of the body, but not so critical. Their deficiency causes disease. They are part of biologically active compounds and affect metabolism.
There are ultramicroelements: Au Ag Be, etc. The physiological role has not been definitively established. But they are important for the cell.
There is the concept of “biochemical endemics” - diseases of plants, animals and humans caused by a sharp deficiency or excess of any element in a certain area. For example, endemic goiter (iodine deficiency).
If there is a deficiency of an element due to diet, illness or illness may also occur. For example, with a lack of iron - anemia. With a lack of calcium - frequent fractures, hair loss, teeth loss, muscle pain.

Minerals (minerals)- natural substances that are approximately homogeneous chemical composition And physical properties, included in rocks, ores, meteorites (from the Latin minera - ore).

Minerals, along with proteins, fats, carbohydrates and vitamins, are vital components of human food, necessary for building the structures of living tissues and carrying out biochemical and physiological processes, which underlie the vital activity of the organism. Minerals participate in the body’s most important metabolic processes: water-salt and acid-base. Many enzymatic processes in the body are impossible without the participation of certain minerals.

The human body receives these elements from the environment, food and water.

The quantitative content of a particular chemical element in the body is determined by its content in external environment, as well as the properties of the element itself, taking into account the solubility of its compounds.

For the first time scientific basis the doctrine of microelements in our country was substantiated by V.I. Vernadsky (1960). Fundamental research was carried out by A.P. Vinogradov (1957) - the founder of the doctrine of biogeochemical provinces and their role in the occurrence of endemic diseases of humans and animals and V.V. Kovalsky (1974) - the founder of geochemical ecology and biogeography of chemical elements.

Currently, out of 92 naturally occurring elements, 81 chemical elements are found in the human body.

Minerals make up a significant part human body by weight (on average, the body contains about 3 kg of ash). In bones, minerals are present in the form of crystals, in soft tissues- in the form of a true or colloidal solution in combination mainly with proteins. For clarity, we can give the following example: the body of an adult contains about 1 kg of calcium, 0.5 kg of phosphorus, 150 g of potassium, sodium and chlorine, 25 g of magnesium, 4 g of iron.

• Classification of chemical elements
  • Classification of chemical elements according to their biological significance. All chemical elements can be divided into groups:
    • The 12 structural elements are carbon, oxygen, hydrogen, nitrogen, calcium, magnesium, sodium, potassium, sulfur, phosphorus, fluorine and chlorine.
    • 15 essential (vital) elements - iron, iodine, copper, zinc, cobalt, chromium, molybdenum, nickel, vanadium, selenium, manganese, arsenic, fluorine, silicon, lithium.
    • 2 conditionally necessary elements - boron and bromine.
    • 4 elements are serious "candidates for necessity" - cadmium, lead, aluminum and rubidium.
    • The remaining 48 elements are less significant for the body.
  • Classification of chemical elements based on a quantitative assessment of their content in the human body Traditionally, all mineral substances are divided into two groups according to their content in the human body.
    • Macroelements.
    • Microelements.

      The concentration of trace elements in the body is low. The body contains quantities measured in milligrams or micrograms. Trace elements are those minerals for which the estimated dietary requirement is typically less than 1 μg/g and often less than 50 ng/g of diet for laboratory animals and humans.

      Despite the low need, these elements are part of enzyme systems as coenzymes (activators and catalysts of biochemical processes). The group of microelements includes: zinc, iodine, fluorine, silicon, chromium, copper, manganese, cobalt, molybdenum, nickel, boron, bromine, arsenic, lead, tin, lithium, cadmium, vanadium and other substances.

• The influence of minerals on the human body.

  Minerals do not have energy value like proteins, fats and carbohydrates. However, without them, human life is impossible. The same as with a lack of basic nutrients or vitamins, when there is a deficiency of minerals in the human body, specific disorders arise, leading to characteristic diseases.

  Microelements and vitamins are in some ways even more important than nutrients, because without them the latter will not be properly absorbed by the body.

  Minerals are especially important for children during periods of intensive growth of bones, muscles, internal organs. Naturally, pregnant women and nursing mothers need increased intake of minerals. With age, the need for minerals decreases.

  • Deficiency and excess intake of minerals

    The influence of micro- and macroelements on the life activity of animals and humans is being actively studied for medical purposes. Any pathology, any deviation in the health of a biological organism is accompanied by either a deficiency of vital (essential) elements, or an excess of both essential and toxic microelements. This imbalance of macro- and microelements received the unifying name “microelementosis”.

    Since the 1970s, there have been many speculative claims that micronutrient deficiencies are a significant contributor to a number of chronic diseases. In many cases, this statement has been experimentally confirmed, but some scientists today believe that insufficient intake of a particular micronutrient is significant only when the body is exposed to stress, which increases the need for this micronutrient.

    Chemical substances, despite their importance and necessity for the human body, can also have a negative effect on plants, animals and humans if the concentration of their available forms exceeds certain limits. Cadmium, tin, lead and rubidium are considered conditionally necessary, because they appear to be of little importance to plants and animals and are hazardous to human health even at relatively low concentrations. The biological role of some trace elements is currently not sufficiently studied.

    It is necessary to remember certain precautions when consuming mineral complexes (such as medicines, and biologically active food additives).

    An overdose of one mineral can lead to functional impairment and increased excretion of another mineral. It is also possible that unwanted side effects. For example, excess zinc leads to a decrease in the level of cholesterol-containing high-density lipids ("good" cholesterol).

    Excess calcium can lead to phosphorus deficiency, and vice versa.

    Excess molybdenum reduces copper content.

    Some trace elements (selenium, chromium, copper) are toxic in excess doses. This especially applies to salts of many metals.

    When consuming minerals, you should strictly adhere to medical recommendations.

  • Effect of heavy metals on the human body

    IN recent years separate the effect of heavy metals on the human body. Heavy metals are a group of chemical elements with a relative atomic mass greater than 40.

    The appearance of the term “heavy metals” in the literature was associated with the manifestation of the toxicity of certain metals and their danger to living organisms.

    However, the “heavy” group also included some microelements, vital necessity and wide range whose biological effects have been irrefutably proven.

    “Heavy” metals are lead, cadmium, zinc, copper, nickel, chromium.

    In recent years, the important biological role of most “heavy” metals has been increasingly confirmed. Numerous studies have established that the influence of metals is very diverse and depends on their content in the environment and the degree of need for them by microorganisms, plants, animals and humans.

    The influence of “heavy” metals on living organisms is very diverse. This is due, firstly, to the chemical characteristics of metals, secondly, to the attitude of organisms towards them and, thirdly, to environmental conditions.

    Already in many regions of the world environment becomes more and more “aggressive” from a chemical point of view. In recent decades, the main objects of biogeochemical research have become the territories of industrial cities and adjacent lands, especially if agricultural plants are grown on them and then used for food.

Modern scientific data on the biological role of the studied chemical elements, their metabolism in the human body, daily consumption rates, and the content of chemicals in food products are presented in separate articles describing each chemical element. The articles also present data on deficiency conditions that develop with insufficient consumption of these chemicals, as well as the body's response to excess consumption of nutrients.

• Macronutrients
  • Table salt

• Microelements