Lesson topic: "Carbohydrates" for the 11th grade of the humanitarian direction

Goals:

educational:

To form students' knowledge about carbohydrates, their composition and classification. Consider the dependence of the chemical properties of carbohydrates on the structure of molecules. Qualitative reactions for glucose and starch. To give an idea of ​​the biological role of carbohydrates, their importance in human life.

developing:

Continue to develop mental operations in students: the ability to connect existing knowledge with newly acquired knowledge, the ability to highlight the main thing in the studied material, to generalize the studied material and draw conclusions.

educational:

Education of a responsible attitude to learning, the desire for creative, cognitive activity.

Type: learning new material

View: lecture

Method : explanatory and illustrative with computer support

Lesson plan

1. Organizing time

2. Motivation for the lesson

Carbohydrates are an important source of nutrition: we consume grains, or we feed them to animals, in whose bodies starch is converted into proteins and fats. The most hygienic clothing is made from cellulose or products based on it: cotton and linen, viscose fiber or acetate silk. Wooden houses and furniture are built from the same pulp that makes up wood. At the heart of the production of photographic and film is still the same cellulose. Books, newspapers, banknotes are all products of the pulp and paper industry. So, carbohydrates provide us with everything we need.

In addition, carbohydrates are involved in the construction of complex proteins, enzymes, hormones. Carbohydrates are also such vital necessary substances, like heparin (it plays a crucial role - it prevents blood clotting), agar-agar (it is obtained from seaweed and are used in the microbiological and confectionery industries).

The only source of energy on Earth (besides nuclear) is the energy of the Sun, and the only way to accumulate it to ensure the vital activity of all living organisms is the process of photosynthesis, which takes place in plant cells and leads to the synthesis of carbohydrates from water and carbon dioxide. By the way, it is during this transformation that oxygen is formed, without which life on our planet would be impossible.

Lecture plan

1. The concept of carbohydrates. Classification of carbohydrates.

2. Monosaccharides

3. Disaccharides

4. Polysaccharides

1. The concept of carbohydrates. Classification of carbohydrates.

Carbohydrates- an extensive class of natural compounds that play an important role in the life of humans, animals and plants .

These compounds received the name "carbohydrates" because the composition of many of them is expressed by the general formula Cn (H 2 O ) m, i.e. formally, they are compounds of carbon and water. With the development of carbohydrate chemistry, compounds have been discovered whose composition does not correspond to the above formula, but possessing the properties of substances of their class (for example, deoxyribose C 5 H 10 O 4). At the same time, there are substances that correspond to the general formula of carbohydrates, but do not exhibit their properties (for example, inositol C 6 H 12 O 6 alcohol).

Classification of carbohydrates

All carbohydrates can be divided into two groups: simple carbohydrates(monosaccharides) and complex carbohydrates.

Simple carbohydrates (monosaccharides) are the simplest carbohydrates that are not hydrolyzed to form simpler carbohydrates.

Complex carbohydrates- these are carbohydrates, the molecules of which consist of two or more monosaccharide residues and decompose into these monosaccharides during hydrolysis.

2. Monosaccharides

Monosaccharides are compounds with mixed functions. They contain an aldehyde or keto group and several hydroxyl groups, i.e. are aldehyde alcohols or keto alcohols.

Monosaccharides with an aldehyde group are called aldoses, and with the keto group - ketosis.

According to the number of carbon atoms in a molecule, monosaccharides are divided into tetroses, pentoses, hexoses etc.

Highest value Among the monosaccharides, they have hexoses and pentoses.

Structure of monosaccharides

Projection projections are used to depict the structure of monosaccharides. Fisher formulas. In Fisher's formulas, the chain of carbon atoms is located in one chain. The chain numbering starts from the atom of the aldehyde group (in the case of aldoses) or from the extreme carbon atom, to which the keto group is located closer (in the case of ketoses).

Depending on the spatial arrangement of the H atoms and OH groups at the 4th carbon atom in pentoses and the 5th carbon atom in hexoses, monosaccharides are assigned to the D - or L - series.

A monosaccharide is classified as a D-series if the OH group of these atoms is located to the right of the chain.

Almost all naturally occurring monosaccharides belong to the D-series.

However, monosaccharides can also exist in cyclic forms. The cyclic forms of hexoses and pentoses are called pyranose and furanose, respectively.

In solutions of monosaccharides, a mobile equilibrium is established between the acyclic and cyclic forms - tautomerism.

Cyclic forms are usually depicted promising Haworth formulas.

In the cyclic forms of monosaccharides, an asymmetric carbon atom appears (C-1 for aldoses, C-2 for ketoses). This carbon atom is called anomeric. If the OH group of an anomeric atom is located under the plane, then an α-anomer is formed, the opposite arrangement leads to the formation of a β-anomer.

Physical properties

Colorless crystalline substances, sweet in taste, highly soluble in water, poorly soluble in alcohol. The sweetness of monosaccharides varies. For example, fructose is 3 times sweeter than glucose.

(slide 8 - 12.)

Chemical properties

The chemical properties of monosaccharides are due to the peculiarities of their structure.

Consider the chemical properties of glucose as an example.

1. Reactions involving the aldehyde group of glucose

A) recovery (hydrogenation) with the formation of polyhydric alcohol sorbitol

CH=O CH 2 OH

│ kat , t 0 │

(CHOH) 4 + H 2 → (CHOH) 4

CH 2 OH CH 2 OH

b) oxidation

"silver mirror" reaction (with ammonia solution of silver oxide,t 0 ),

reaction with copper hydroxide (II ) Cu (Oh ) 2 in an alkaline environmentt 0 )

CH=OCOOH

│ NH 4 OH, t 0 │

(CHOH) 4 + Ag 2 O → (CHOH) 4

CH 2 OH CH 2 OH

The oxidation product is gluconic acid (the salt of this acid is calcium gluconate, a well-known drug).

CH=OCOOH

│ t0 │

(CHOH) 4 + 2Cu(OH) 2 → (CHOH) 4 + Cu 2 O↓ + 2H 2 O

│ blue │ brick red

CH 2 OH CH 2 OH

These reactions are qualitative for glucose as an aldehyde.

Under the action of strong oxidizing agents (for example, nitric acid), dibasic glucaric acid is formed.

CH=OCOOH

│ t0 │

(CHOH) 4 + HNO 3 → (CHOH) 4

CH2OHCOOH

2. The reaction of glucose with the participation of hydroxyl groups (i.e. the properties of glucose as a polyhydric alcohol)

A) interaction Cu (Oh ) 2 in the cold with the formation of copper (II) gluconate - a qualitative reaction for glucose as a polyhydric alcohol.

3. Fermentation (fermentation) of monosaccharides

A) alcoholic fermentation

C 6 H 12 O 6 → 2C 2 H 5 OH + 2CO 2

b) butyric fermentation

C 6 H 12 O 6 → CH 3 ─CH 2 ─CH 2 ─COOH + 2H 2 + 2CO 2

V) lactic fermentation

C 6 H 12 O 6 → 2CH 3 ─ CH ─ COOH

HE

Biological role glucose

D-glucose (grape sugar) is widely distributed in nature: found in grapes and other fruits, in honey. It is an essential component of the blood and tissues of animals and a direct source of energy for cellular reactions. The level of glucose in human blood is constant and is in the range of 0.08-0.11%. The entire blood volume of an adult contains 5-6 g of glucose. This amount is sufficient to cover the body's energy costs for 15 minutes. his life activity. For some pathologies, for example, with a disease diabetes The blood glucose level rises and the excess is excreted in the urine. At the same time, the amount of glucose in the urine can increase up to 12% against the usual 0.1%.

3. Disaccharides

(slide 13.)

Disaccharides - condensation products of two monosaccharides.

The most important natural representatives: sucrose (cane or beet sugar), maltose (malt sugar), lactose (milk sugar), cellobiose. All of them have the same empirical formula C 12 H 22 O 11, i.e. are isomers.

Disaccharides are typical sugar-like carbohydrates; These are solid crystalline substances that have a sweet taste.

(slide 14-15.)

Structure

1. Disaccharide molecules may contain two residues of one monosaccharide or two residues of different monosaccharides;

2. The bonds formed between monosaccharide residues can be of two types:

a) hemiacetal hydroxyls of both monosaccharide molecules take part in the bond formation. For example, the formation of a sucrose molecule;

b) the hemiacetal hydroxyl of one monosaccharide and the alcohol hydroxyl of another monosaccharide take part in the formation of the bond. For example, the formation of molecules of maltose, lactose and cellobiose.

(slide 16-17.)

Chemical properties of disaccharides

1. Disaccharides, in the molecules of which hemiacetal hydroxyl (maltose, lactose, cellobiose) is preserved, in solutions are partially converted into open aldehyde forms and enter into reactions characteristic of aldehydes, in particular, into the “silver mirror” reaction and with copper (II) hydroxide . These disaccharides are called restoring.

Disaccharides, in the molecules of which there is no hemiacetal hydroxyl (sucrose) cannot pass into open carbonyl groups. These disaccharides are called non-reducing(do not restore Cu (OH) 2 and Ag 2 O).

2. All disaccharides are polyhydric alcohols, they are characterized by the properties of polyhydric alcohols, they give a qualitative reaction to polyhydric alcohols - a reaction with Cu (OH) 2 in the cold.

3. All disaccharides are hydrolyzed to form monosaccharides:

H+, t0

C 12 H 22 O 11 + H 2 O → C 6 H 12 O 6 + C 6 H 12 O 6

sucrose glucose fructose

In living organisms, hydrolysis occurs under the action of enzymes.

4. Polysaccharides

(slide 18 - 20.)

Polysaccharides- high-molecular non-sugar-like carbohydrates containing from ten to hundreds of thousands of monosaccharide residues (usually hexoses) linked by glycosidic bonds.

The most important natural representatives: starch, glycogen, cellulose. These are natural polymers (VMC), the monomer of which is glucose. Their general empirical formula is (C 6 H 10 O 5) n.

Starch– amorphous powder white color, tasteless and odorless, poorly soluble in water, forms a colloidal solution in hot water. Starch macromolecules are built from a large number of α-glucose residues linked by α-1,4-glycosidic bonds.

Starch consists of two fractions: amylose (20-30%) and amylopectin (70-80%).

Amylose molecules are very long unbranched chains consisting of α-glucose residues. Amylopectin molecules, unlike amylose, are highly branched.

Chemical properties of starch:

(slide 21.)

1. hydrolysis

H 2 O, enzymes

(C 6 H 10 O 5) n → (C 6 H 10 O 5) m → C 12 H 22 O 11 → n C 6 H 12 O 6

starch dextrins maltose glucose

The reaction of the conversion of starch into glucose under the catalytic action of sulfuric acid was discovered in 1811 by the Russian scientist K. Kirchhoff.

2. Qualitative reaction to starch

(C 6 H 10 O 5) n + I 2 → blue-violet complex compound.

When heated, the coloring disappears (the complex is destroyed), when cooled, it reappears.

Starch is one of the products of photosynthesis, the main reserve nutrient of plants. Residues of glucose in starch molecules are connected quite firmly and at the same time, under the action of enzymes, they can easily be split off. As soon as there is a need for a source of energy.

Glycogen is the equivalent of starch synthesized in the animal body, i.e. it is also a reserve polysaccharide, the molecules of which are built from a large number of α-glucose residues. Glycogen is found mainly in the liver and muscles.

Cellulose or fiber

The main component of the plant cell is synthesized in plants (up to 60% cellulose in wood). Pure cellulose is a white fibrous substance, tasteless and odorless, insoluble in water.

Cellulose molecules are long chains consisting of β-glucose residues that are connected by the formation of β-1,4-glycosidic bonds.

Unlike starch molecules, cellulose consists only of unbranched molecules in the form of filaments, since the shape of β-glucose residues precludes coiling.

Cellulose is not a food product for humans and most animals, because. in their organisms there are no enzymes that break down stronger β-1,4-glycosidic bonds.

(slide 22-23.)

Chemical properties of cellulose:

1. hydrolysis

On prolonged heating with mineral acids or under the action of enzymes (in ruminants and rabbits) there is a stepwise hydrolysis:

H 2 O

(C 6 H 10 O 5) n → y (C 6 H 10 O 5) x → n / 2 C 12 H 22 O 11 → n C 6 H 12 O 6

cellobiose cellulose β-glucose

2. ester formation

a) interaction with organic acids

b) interaction with organic acids

3. burning

(C 6 H 10 O 5) n + 6nO 2 → 6nCO 2 + 5nH 2 O

4. thermal decomposition of cellulose without air access:

t0

(C 6 H 10 O 5) n → charcoal+ H 2 O + volatile organic substances

Being an integral part of wood, cellulose is used in construction and carpentry; as fuel; paper, cardboard, ethyl alcohol are obtained from wood. In the form of fibrous materials (cotton, linen), cellulose is used to make fabrics and threads. Cellulose ethers are used in the manufacture of nitro-varnishes, plastics, medical collodion, and artificial fibers.

Carbohydrates aldoses, and ketone - ketosis

Functions of carbohydrates in the body.

The main functions of carbohydrates in the body:

1. Energy function. Carbohydrates are one of the main sources of energy for the body, providing at least 60% of energy costs. For the activity of the brain, kidneys, blood, almost all energy is supplied by the oxidation of glucose. With the complete breakdown of 1 g of carbohydrates, 17.15 kJ / mol or 4.1 kcal / mol of energy is released.

2. Plastic or structural function. Carbohydrates and their derivatives are found in all cells of the body. In plants, fiber serves as the main supporting material; in the human body, bones and cartilage contain complex carbohydrates. Heteropolysaccharides, such as hyaluronic acid, are part of cell membranes and cell organelles. Participate in the formation of enzymes, nucleoproteins (ribose, deoxyribose), etc.

3. Protective function. Viscous secretions (mucus) secreted by various glands are rich in carbohydrates or their derivatives (mucopolysaccharides, etc.), they protect the inner walls of the genital organs of the gastrointestinal tract, airways, etc. from mechanical and chemical influences, penetration of pathogenic microbes. In response to antigens in the body, immune bodies are synthesized, which are glycoproteins. Heparin protects blood from clotting (included in the anticoagulant system) and performs an antilipidemic function.

4. regulatory function. Human food contains a large number of fiber, the rough structure of which causes mechanical irritation of the mucous membrane of the stomach and intestines, thus participating in the regulation of the act of peristalsis. Blood glucose is involved in the regulation of osmotic pressure and the maintenance of homeostasis.

5. specific functions. Some carbohydrates perform special functions in the body: they are involved in the conduction of nerve impulses, ensuring the specificity of blood groups, etc.

Classification of carbohydrates.

Carbohydrates are classified according to the size of the molecules into 3 groups:

1. Monosaccharides- contain 1 carbohydrate molecule (aldoses or ketoses).

Trioses (glyceraldehyde, dihydroxyacetone).

Tetroses (erythrosis).

Pentoses (ribose and deoxyribose).

Hexoses (glucose, fructose, galactose).

2. Oligosaccharides- contain 2-10 monosaccharides.

Disaccharides (sucrose, maltose, lactose).

· Trisaccharides, etc.

3. Polysaccharides- contain more than 10 monosaccharides.

Homopolysaccharides - contain the same monosaccharides (starch, fiber, cellulose consist only of glucose).

Heteropolysaccharides - contain monosaccharides different kind, their steam derivatives and non-carbohydrate components (heparin, hyaluronic acid, chondroitin sulfates).

Scheme No. 1. K classification of carbohydrates.

Carbohydrates

Monosaccharides Oligosaccharides Polysaccharides

1. Trioses 1. Disaccharides 1. Homopolysaccharides

2. Tetroses 2. Trisaccharides 2. Heteropolysaccharides

3. Pentoses 3. Tetrasaccharides

4. Hexoses

properties of carbohydrates.

1. Carbohydrates are solid crystalline white substances, almost everything tastes sweet.

2. Almost all carbohydrates are highly soluble in water, and true solutions are formed. The solubility of carbohydrates depends on the mass (the greater the mass, the less soluble the substance, for example, sucrose and starch) and the structure (the more branched the structure of the carbohydrate, the worse the solubility in water, for example, starch and fiber).

3. Monosaccharides can be found in two stereoisomeric forms: L-shape (leavus - left) and D-shape (dexter - right). These forms have the same chemical properties, but differ in the arrangement of hydroxide groups relative to the axis of the molecule and in optical activity, i.e. rotate through a certain angle the plane of polarized light that passes through their solution. Moreover, the plane of polarized light rotates by one amount, but in opposite directions. Consider the formation of stereoisomers using the example of glyceraldehyde:

AtoN AtoN

BUT-S-N H-S- HE

CH2OH CH2OH

L - shape D - shape

When monosaccharides are obtained in the laboratory, stereoisomers are formed in a ratio of 1: 1; in the body, synthesis occurs under the action of enzymes that strictly distinguish between the L-form and the D-form. Since only D-sugars are synthesized and broken down in the body, L-stereoisomers gradually disappeared in evolution (this is the basis for the determination of sugars in biological fluids using a polarimeter).

4. Monosaccharides in aqueous solutions can interconvert, this property is called mutation.

HO-CH2 O=C-H

S O NO-S-N

N N H H-C-OH

S S NO-S-N

BUT OH N HE BUT-S-N

C C CH2-OH

HO-CH2

N N HE

BUT OH N H

Beta form.

In aqueous solutions, monomers consisting of 5 or more atoms can be found in cyclic (ring) alpha or beta forms and open (open) forms, and their ratio is 1:1. Oligo- and polysaccharides are composed of monomers in cyclic form. In the cyclic form, carbohydrates are stable and milk-active, and in the open form they are highly reactive.

5. Monosaccharides can be reduced to alcohols.

6. In an open form, they can interact with proteins, lipids, nucleotides without the participation of enzymes. These reactions are called glycation. The clinic uses a study of the level of glycosylated hemoglobin or fructosamine to diagnose diabetes mellitus.

7. Monosaccharides can form esters. Of greatest importance is the property of carbohydrates to form esters with phosphoric acid, tk. in order to be included in the metabolism, a carbohydrate must become a phosphate ester, for example, glucose is converted into glucose-1-phosphate or glucose-6-phosphate before oxidation.

8. Aldolases have the ability to reduce metals in an alkaline environment from their oxides to oxide or to a free state. This property is used in laboratory practice to detect aldolose (glucose) in biological fluids. Most often used Trommer reaction in which aldolose reduces copper oxide to oxide, and itself is oxidized to gluconic acid (1 carbon atom is oxidized).

CuSO4 + NaOH Cu(OH)2 + Na2SO4

Blue

C5H11COH + 2Cu(OH)2 C5H11COOH + H2O + 2CuOH

brick red

9. Monosaccharides can be oxidized to acids not only in the Trommer reaction. For example, when the 6 carbon atom of glucose is oxidized in the body, glucuronic acid is formed, which combines with toxic and poorly soluble substances, neutralizes them and converts them into soluble ones, in this form these substances are excreted from the body with urine.

10. Monosaccharides can combine with each other and form polymers. The connection that occurs is called glycosidic, it is formed by the OH group of the first carbon atom of one monosaccharide and the OH group of the fourth (1,4-glycosidic bond) or sixth carbon atom (1,6-glycosidic bond) of another monosaccharide. In addition, an alpha-glycosidic bond (between two alpha forms of a carbohydrate) or a beta-glycosidic bond (between the alpha and beta forms of a carbohydrate) can form.

11. Oligo- and polysaccharides can undergo hydrolysis to form monomers. The reaction proceeds at the site of the glycosidic bond, and this process is accelerated in an acidic environment. Enzymes in the human body can distinguish between alpha and beta glycosidic bonds, so starch (which has alpha glycosidic bonds) is digested in the gut, but fiber (which has beta glycosidic bonds) is not.

12. Mono- and oligosaccharides can be fermented: alcohol, lactic acid, citric acid, butyric.

general characteristics carbohydrates.

Carbohydrates- organic compounds that are aldehydes or ketones of polyhydric alcohols. Carbohydrates containing an aldehyde group are called aldoses, and ketone - ketosis. Most of them (but not all! For example, rhamnose C6H12O5) correspond to the general formula Cn (H2O) m, which is why they got their historical name - carbohydrates. But there are a number of substances, for example, acetic acid C2H4O2 or CH3COOH, which, although it corresponds to the general formula, does not apply to carbohydrates. Currently, another name has been adopted that most accurately reflects the properties of carbohydrates - glucides (sweet), but the historical name has become so firmly established in life that they continue to use it. Carbohydrates are very widespread in nature, especially in the plant kingdom, where they make up 70-80% of the dry matter mass of cells. In the animal body, they account for only about 2% of body weight, but here their role is no less important. The share of their participation in the overall energy balance is very significant, exceeding almost one and a half times the share of proteins and lipids combined. In the body, carbohydrates can be stored as glycogen in the liver and consumed as needed.

Carbohydrates are the main source of energy in the human body.

General formula of carbohydrates Сn(H2O)m

Carbohydrates - substances of composition Cm H2n Op, which are of paramount biochemical importance, are widespread in wildlife and play big role In human life. Carbohydrates are part of the cells and tissues of all plant and animal organisms and, by mass, make up the bulk of the organic matter on Earth. Carbohydrates account for about 80% of the dry matter of plants and about 20% of animals. Plants synthesize carbohydrates from inorganic compounds - carbon dioxide and water (CO2 and H2O).

The reserves of carbohydrates in the form of glycogen in the human body are approximately 500 g. The bulk of it (2/3) is in the muscles, 1/3 is in the liver. Between meals, glycogen breaks down into glucose molecules, which dampens fluctuations in blood sugar levels. Glycogen stores without carbohydrate intake are depleted in about 12-18 hours. In this case, the mechanism for the formation of carbohydrates from the intermediate products of protein metabolism is activated. This is due to the fact that carbohydrates are vital for the formation of energy in tissues, especially the brain. Brain cells obtain energy primarily from the oxidation of glucose.

Types of carbohydrates

Carbohydrates can be divided into simple carbohydrates (monosaccharides and disaccharides) and complex carbohydrates (polysaccharides) according to their chemical structure.

Simple carbohydrates (sugars)

Glucose is the most important of all monosaccharides, as it is the structural unit of most dietary di- and polysaccharides. In the process of metabolism, they are broken down into individual molecules of monosaccharides, which, during multi-stage chemical reactions, are converted into other substances and ultimately oxidized to carbon dioxide and water - used as "fuel" for cells. Glucose is an essential component of carbohydrate metabolism. With a decrease in its level in the blood or a high concentration and the inability to use, as happens with diabetes, drowsiness occurs, loss of consciousness (hypoglycemic coma) may occur.

Glucose "in its pure form", as a monosaccharide, is found in vegetables and fruits. Especially rich in glucose are grapes - 7.8%, cherries, cherries - 5.5%, raspberries - 3.9%, strawberries - 2.7%, plums - 2.5%, watermelon - 2.4%. Of the vegetables, most glucose is found in pumpkin - 2.6%, in white cabbage - 2.6%, in carrots - 2.5%.

Glucose is less sweet than the most famous disaccharide, sucrose. If we take the sweetness of sucrose as 100 units, then the sweetness of glucose will be 74 units.

Fructose is one of the most common fruit carbohydrates. Unlike glucose, it can penetrate from the blood into tissue cells without the participation of insulin. For this reason, fructose is recommended as the safest carbohydrate source for diabetics. Part of the fructose enters the liver cells, which turn it into a more universal "fuel" - glucose, so fructose is also able to increase blood sugar, although to a much lesser extent than other simple sugars. Fructose is more easily converted into fat than glucose. The main advantage of fructose is that it is 2.5 times sweeter than glucose and 1.7 times sweeter than sucrose. Its use instead of sugar allows you to reduce the total consumption of carbohydrates.

The main sources of fructose in food are grapes - 7.7%, apples - 5.5%, pears - 5.2%, cherries, sweet cherries - 4.5%, watermelons - 4.3%, black currants - 4.2% , raspberries - 3.9%, strawberries - 2.4%, melons - 2.0%. In vegetables, the fructose content is low - from 0.1% in beets to 1.6% in white cabbage. Fructose is found in honey - about 3.7%. Fructose, which has a much higher sweetness than sucrose, has been well proven to not cause tooth decay, which is promoted by sugar consumption.

Galactose is not found in free form in foods. It forms a disaccharide with glucose - lactose (milk sugar) - the main carbohydrate of milk and dairy products.

Lactose is broken down in the gastrointestinal tract to glucose and galactose by the enzyme lactase. Deficiency of this enzyme in some people leads to milk intolerance. Undigested lactose serves as a good nutrient for the intestinal microflora. At the same time, abundant gas formation is possible, the stomach “swells”. In fermented milk products, most of the lactose is fermented to lactic acid, so people with lactase deficiency can tolerate fermented milk products without unpleasant consequences. In addition, lactic acid bacteria in fermented milk products inhibit the activity of the intestinal microflora and reduce the adverse effects of lactose.

Galactose, formed during the breakdown of lactose, is converted into glucose in the liver. With a congenital hereditary deficiency or absence of an enzyme that converts galactose into glucose, a serious disease develops - galactosemia, which leads to mental retardation.

Sucrose is a disaccharide formed by molecules of glucose and fructose. The content of sucrose in sugar is 99.5%. That sugar is the "white death", sweet lovers know as well as smokers that a drop of nicotine kills a horse. Unfortunately, both of these common truths are more often an occasion for jokes than for serious reflection and practical conclusions.

Sugar is rapidly broken down in the gastrointestinal tract, glucose and fructose are absorbed into the blood and serve as a source of energy and the most important precursor of glycogen and fats. It is often referred to as an "empty calorie carrier" because sugar is a pure carbohydrate and does not contain other nutrients such as vitamins and mineral salts. Of the vegetable products, the most sucrose is found in beets - 8.6%, peaches - 6.0%, melons - 5.9%, plums - 4.8%, tangerines - 4.5%. In vegetables, except for beets, a significant content of sucrose is noted in carrots - 3.5%. In other vegetables, the sucrose content ranges from 0.4 to 0.7%. In addition to sugar itself, the main sources of sucrose in food are jam, honey, confectionery, sweet drinks, ice cream.

When two glucose molecules combine, maltose is formed - malt sugar. It contains honey, malt, beer, molasses and bakery and confectionery products made with the addition of molasses.

Complex carbohydrates

All polysaccharides present in human food, with rare exceptions, are glucose polymers.

Starch is the main digestible polysaccharide. It accounts for up to 80% of carbohydrates consumed with food.

The source of starch is vegetable products, mainly cereals: cereals, flour, bread, and potatoes. Cereals contain the most starch: from 60% in buckwheat (kernel) to 70% in rice. Of the cereals, the least starch is found in oatmeal and its processed products: oatmeal, oatmeal"Hercules" - 49%. Pasta contains from 62 to 68% starch, rye flour bread, depending on the variety, from 33% to 49%, wheat bread and other products made from wheat flour - from 35 to 51% starch, flour - from 56 (rye) to 68% (wheat premium). There is also a lot of starch in legumes - from 40% in lentils to 44% in peas. For this reason, dry peas, beans, lentils, chickpeas are classified as legumes. Soybean, which contains only 3.5% starch, and soy flour (10-15.5%) stand apart. Due to the high starch content in potatoes (15-18%) in dietology, it is not classified as a vegetable, where the main carbohydrates are monosaccharides and disaccharides, but as starchy foods along with cereals and legumes.

In Jerusalem artichoke and some other plants, carbohydrates are stored in the form of a polymer of fructose - inulin. food products with the addition of inulin is recommended for diabetes and especially for its prevention (recall that fructose puts less stress on the pancreas than other sugars).

Glycogen - "animal starch" - consists of highly branched chains of glucose molecules. It is found in small amounts in animal products (2-10% in the liver, 0.3-1% in muscle tissue).

Foods high in carbohydrates

The most common carbohydrates are glucose, fructose, and sucrose, found in vegetables, fruits, and honey. Lactose is part of milk. Refined sugar is a compound of fructose and glucose.

Glucose plays a central role in the metabolic process. It is an energy supplier for organs such as the brain, kidneys, and contributes to the production of red blood cells.

The human body is not able to make too large reserves of glucose and therefore needs its regular replenishment. But this does not mean that you need to eat glucose in its pure form. It is much more useful to use it as part of more complex carbohydrate compounds, such as starch, which is found in vegetables, fruits, and grains. All these products, in addition, are a real storehouse of vitamins, fiber, trace elements and other useful substances that help the body fight many diseases. Polysaccharides must be most all the carbohydrates that enter our body.

The most important sources of carbohydrates

The main sources of carbohydrates from food are: bread, potatoes, pasta, cereals, sweets. The net carbohydrate is sugar. Honey, depending on its origin, contains 70-80% glucose and fructose.

To indicate the amount of carbohydrates in food, a special bread unit is used.

In addition, fiber and pectins that are poorly digested by the human body adjoin the carbohydrate group.

Carbohydrates are used as:

Medicines,

For the production of smokeless powder (pyroxylin),

explosives,

Artificial fibers (viscose).

Cellulose is of great importance as a source for obtaining ethyl alcohol

1. Energy

The main function of carbohydrates is that they are an indispensable component of the human diet, with the breakdown of 1 g of carbohydrates, 17.8 kJ of energy is released.

2. Structural.

The cell wall of plants is made up of the polysaccharide cellulose.

3. Spare.

Starch and glycogen are storage products in plants and animals.

Historical reference

Carbohydrates have been used since ancient times - the very first carbohydrate (more precisely, a mixture of carbohydrates) that a person met was honey.

· Homeland of sugar cane is northwestern India-Bengal. Europeans got acquainted with cane sugar thanks to the campaigns of Alexander the Great in 327 BC.

Starch was known to the ancient Greeks.

Pure beet sugar was discovered only in 1747 by the German chemist A. Marggraf

In 1811, the Russian chemist Kirchhoff was the first to obtain glucose by the hydrolysis of starch

For the first time, the Swedish chemist J. Berzellius proposed the correct empirical formula for glucose in 1837. С6Н12О6

· The synthesis of carbohydrates from formaldehyde in the presence of Ca(OH)2 was carried out by A.M. Butlerov in 1861

Conclusion

The importance of carbohydrates cannot be overestimated. Glucose is the main energy source in the human body, goes to the construction of many important substances in the body - glycogen (energy reserve), is part of cell membranes, enzymes, glycoproteins, glycolipids, participates in most reactions occurring in the human body. At the same time, it is sucrose that is the main source of glucose, which enters the internal environment. Containing in almost all plant foods, sucrose provides the necessary influx of energy and an indispensable substance - glucose.

The body definitely needs carbohydrates (over 56% of the energy we get from carbohydrates)

Carbohydrates are simple and complex (because of the structure of the molecules they were called so)

The minimum amount of carbohydrates should be at least 50-60 g

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Nutrition

What are carbohydrates?

• What are carbohydrates?
• What are the “right” carbohydrate sources and how to include them in your diet?
• What is the glycemic index?
• How is the breakdown of carbohydrates?
• Do they really turn into body fat after processing?

Starting with theory

Carbohydrates (also called saccharides) are organic compounds of natural origin, which are mostly found in the plant world. They are formed in plants during photosynthesis and are found in almost any plant food. Carbohydrates include carbon, oxygen and hydrogen. IN human body carbohydrates come mainly from food (found in cereals, fruits, vegetables, legumes and other products), and are also produced from certain acids and fats.

Carbohydrates are not only the main source of human energy, but also perform a number of other functions:

Of course, if we consider carbohydrates solely in terms of building muscle mass, then they act as an available source of energy. In general, in the body, the energy reserve is contained in fat depots (about 80%), in protein - 18%, and carbohydrates account for only 2%.

Important: Carbohydrates accumulate in the human body in combination with water (1g of carbohydrates requires 4g of water). But fat deposits do not need water, so it is easier to accumulate them, and then use them as a backup energy source.

All carbohydrates can be divided into two types (see image): simple (monosaccharides and disaccharides) and complex (oligosaccharides, polysaccharides, fiber).

Monosaccharides (simple carbohydrates)

They contain one sugar group, for example: glucose, fructore, galactose. And now about each in more detail.

Glucose- is the main "fuel" of the human body and supplies energy to the brain. It also takes part in the formation of glycogen, and for the normal functioning of red blood cells, about 40 g of glucose per day is needed. Together with food, a person consumes about 18g, and the daily dose is 140g (necessary for the proper functioning of the central nervous system).

A natural question arises, where does the body then draw the necessary amount of glucose for its work? About everything in order. In the human body, everything is thought out to the smallest detail, and glucose reserves are stored in the form of glycogen compounds. And as soon as the body requires "refueling", some of the molecules are split and used.

The level of glucose in the blood is a relatively constant value and is regulated by a special hormone (insulin). As soon as a person consumes a lot of carbohydrates, and the glucose level rises sharply, insulin takes over, which lowers the amount to the required level. And you don’t have to worry about the portion of carbohydrates eaten, exactly as much as the body requires (due to the work of insulin) will enter the bloodstream.

Foods rich in glucose are:

• Grapes - 7.8%;
• Cherries and sweet cherries - 5.5%;
• Raspberry - 3.9%;
• Pumpkin - 2.6%;
• Carrot - 2.5%.

Important: the sweetness of glucose reaches 74 units, and sucrose - 100 units.

Fructose is a naturally occurring sugar found in fruits and vegetables. But it is important to remember that consuming large amounts of fructose is not only not beneficial, but also harmful. Huge portions of fructose enter the intestines and cause increased secretion of insulin. And if now you are not engaged in active physical activity, then all glucose is stored in the form of body fat. The main sources of fructose are foods such as:

• Grapes and apples;
• Melons and pears;

Fructose is much sweeter than glucose (2.5 times), but despite this, it does not destroy teeth and does not cause caries. Galactose is not found in free form almost anywhere, but most often it is a component of milk sugar, called lactose.

Disaccharides (simple carbohydrates)

The composition of disaccharides always includes simple sugars (in the amount of 2 molecules) and one molecule of glucose (sucrose, maltose, lactose). Let's look at each of them in more detail.

Sucrose is made up of fructose and glucose molecules. Most often, it is found in everyday life in the form of ordinary sugar, which we use during cooking and simply put in tea. So it is this sugar that is deposited in the layer of subcutaneous fat, so you should not get carried away with the amount consumed, even in tea. The main sources of sucrose are sugar and beets, plums and jam, ice cream and honey.

Maltose is a compound of 2 glucose molecules, which are found in large quantities in such products as: beer, young, honey, molasses, any confectionery. Lactose, on the other hand, is mainly found in dairy products, and is broken down in the intestines and converted into galactose and glucose. Most lactose is found in milk, cottage cheese, kefir.

So we figured out the simple carbohydrates, it's time to move on to complex ones.

Complex carbohydrates

All complex carbohydrates can be divided into two categories:

• Those that are digested (starch);
• Those that are not digested (fiber).

Starch is the main source of carbohydrates that underlies the food pyramid. Most of it is found in cereals, legumes and potatoes. The main sources of starch are buckwheat, oatmeal, pearl barley, as well as lentils and peas.

Important: Use baked potatoes in your diet, which are high in potassium and other minerals. This is especially important because starch molecules swell during cooking and reduce the useful value of the product. That is, at first the product may contain 70%, and after cooking it may not remain 20%.

Fiber plays a very important role in the functioning of the human body. With its help, the work of the intestines and the entire gastrointestinal tract as a whole is normalized. It also creates the necessary nutrient medium for the development of important microorganisms in the intestine. The body practically does not digest fiber, but provides a feeling of rapid satiety. Vegetables, fruits and wholemeal bread (which are high in fiber) are used to prevent obesity (because they quickly make you feel full).

Now let's move on to other processes associated with carbohydrates.

How the body stores carbohydrates

The reserves of carbohydrates in the human body are located in the muscles (2/3 of the total is located), and the rest is in the liver. The total supply is enough for only 12-18 hours. And if you do not replenish the reserves, then the body begins to experience a shortage, and synthesizes the substances it needs from proteins and intermediate metabolic products. As a result, glycogen stores in the liver can be significantly depleted, which will cause the deposition of fats in its cells.

By mistake, many people who lose weight for a more “effective” result significantly cut the amount of carbohydrates consumed, hoping that the body will use up fat stores. In fact, proteins go first, and only then fat deposits. It is important to remember that a large amount of carbohydrates will lead to rapid weight gain only if they are ingested in large portions (and they must also be quickly absorbed).

Carbohydrate metabolism

Carbohydrate metabolism depends on how much glucose is in circulatory system and is divided into three types of processes:

• Glycolysis - glucose is broken down, as well as other sugars, after which the required amount of energy is produced;
• Glycogenesis - glycogen and glucose are synthesized;
• Glyconeogenesis - in the process of splitting glycerol, amino acids and lactic acid in the liver and kidneys, the necessary glucose is formed.

In the early morning (after waking up), blood glucose reserves drop sharply for a simple reason - the lack of nourishment in the form of fruits, vegetables and other foods that contain glucose. The body is also fed by its own forces, 75% of which is carried out in the process of glycolysis, and 25% falls on gluconeogenesis. That is, it turns out that the morning time is considered optimal in order to use the available fat reserves as an energy source. And add to this light cardio loads, you can get rid of a few extra pounds.

Now we finally move on to the practical part of the question, namely: what carbohydrates are good for athletes, as well as in what optimal amounts they should be consumed.

Carbohydrates and bodybuilding: who, what, how much

A few words about the glycemic index

When it comes to carbohydrates, one cannot fail to mention such a term as "glycemic index" - that is, the rate at which carbohydrates are absorbed. It is an indicator of the speed with which a particular product is able to increase the amount of glucose in the blood. The highest glycemic index is 100 and refers to glucose itself. The body, after consuming food with a high glycemic index, begins to store calories and deposits fat deposits under the skin. So all foods with high GI are faithful companions in order to rapidly gain extra pounds.

Foods with a low GI index are a source of carbohydrates, which long time, constantly and evenly nourishes the body and ensures a systematic flow of glucose into the blood. With their help, you can properly adjust the body for a long feeling of satiety, as well as prepare the body for active physical activity in the hall. There are even special tables for foods that list the glycemic index (see image).

The body's need for carbohydrates and the right sources

So the moment has come when we will figure out how many carbohydrates you need to consume in grams. It is logical to assume that bodybuilding is a very energy-consuming process. Therefore, if you want the quality of training not to suffer, you need to provide your body with a sufficient amount of “slow” carbohydrates (about 60-65%).

• duration of training;
• load intensity;
• metabolic rate in the body.

It is important to remember that you do not need to go below the bar of 100g per day, and also have 25-30g in reserve, which fall on fiber.

Remember also that a common person per day consumes about 250-300g of carbohydrates. For those who work out in the weight room, daily rate increases and reaches 450-550g. But they still need to be used correctly, and at the right time (in the morning). Why do you need to do it this way? The scheme is simple: in the first half of the day (after sleep), the body accumulates carbohydrates in order to “feed” their body with them (which is necessary for muscle glycogen). The remaining time (after 12 hours) carbohydrates are quietly deposited in the form of fat. So stick to the rule: more in the morning, less in the evening. After training, it is important to adhere to the rules of the protein-carbohydrate window.

Important: protein-carbohydrate window - a short period of time during which the human body becomes able to absorb an increased amount of nutrients (used to restore energy and muscles).

It has already become clear that the body needs to constantly receive nourishment in the form of “correct” carbohydrates. And to understand the quantitative values, consider the table below.

The concept of “correct” carbohydrates includes those substances that have a high biological value (amount of carbohydrates / 100 g of product) and a low glycemic index. These include products such as:

• Baked or boiled potatoes in their skins;
• Various cereals (oatmeal, barley, buckwheat, wheat);
• Bakery products from wholemeal flour and with bran;
• Pasta (from durum wheat);
• Fruits that are low in fructose and glucose (grapefruits, apples, pomelo);
• Vegetables are fibrous and starchy (turnips and carrots, pumpkins and squash).

These are the foods that should be included in your diet.

The ideal time to consume carbohydrates

Most right time to consume a dose of carbohydrates is:

• Time after morning sleep;
• Before training;
• After training;
• During a workout.

Moreover, each of the periods is important and among them there is no more or less suitable one. Also in the morning, in addition to healthy and slow carbohydrates, you can eat something sweet (a small amount of fast carbohydrates).

Before you go to training (2-3 hours), you need to feed the body with carbohydrates with average glycemic index. For example, eat pasta or corn/rice porridge. This will provide the necessary supply of energy for the muscles and brain.

During classes in the gym, you can use intermediate nutrition, that is, drink drinks containing carbohydrates (every 20 minutes, 200 ml). This will have a double benefit:

• Replenishment of fluid reserves in the body;
• Replenishment of muscle glycogen depot.

After training, it is best to take a rich protein-carbohydrate shake, and after 1-1.5 hours after the end of the training, eat a heavy meal. Buckwheat or barley porridge or potatoes are best suited for this.

Now is the time to talk about the role carbohydrates play in the muscle building process.

Do carbs help build muscle?

It is generally accepted that only proteins are the building material for muscles and only they need to be consumed in order to build muscle mass. In fact, this is not entirely true. What's more, carbohydrates not only help with muscle building, they can help in the fight against extra pounds. But all this is possible only if they are consumed correctly.

Important: in order for the body to have 0.5 kg of muscle, you need to burn 2500 calories. Naturally, proteins cannot provide such an amount, so carbohydrates come to the rescue. They provide the body with the necessary energy and protect proteins from destruction, allowing them to act as building blocks for muscles. Also, carbohydrates contribute to the rapid burning of fat. This is due to the fact that a sufficient amount of carbohydrates contributes to the consumption of fat cells, which are constantly burned during exercise.

It must also be remembered that, depending on the level of training of the athlete, his muscles can store a larger supply of glycogen. To build muscle mass, you need to take 7g of carbohydrates for every kilogram of body. Do not forget that if you began to take more carbohydrates, then the intensity of the load must also be increased.

So that you have already fully understood all the characteristics of nutrients and understand what and how much you need to consume (depending on age, physical activity and gender), carefully study the table below.

• Group 1 - predominantly mental / sedentary work.
• Group 2 - service sector / active sedentary work.
• Group 3 - work of medium severity - locksmiths, machine operators.
• Group 4 - hard work - builders, oilmen, metallurgists.
• Group 5 - very hard work - miners, steelworkers, loaders, athletes during the competitive period.

And now the results

To ensure that the effectiveness of training is always on top, and you have a lot of strength and energy for this, it is important to adhere to certain rules:

• The diet for 65-70% should consist of carbohydrates, and they must be “correct” with a low glycemic index;
• Before training, you need to consume foods with average GI indicators, after training - with low GI;
• Breakfast should be as dense as possible, and in the morning you need to eat most of daily dose carbohydrates;
• When buying foods, check the glycemic index table and choose those that have medium and low rates GI;
• If you want to eat foods with high GI values ​​(honey, jam, sugar), it is better to do this in the morning;
• Include more cereals in your diet and eat them regularly;
• Remember, carbohydrates are protein assistants in the process of building muscle mass, so if there is no tangible result for a long time, then you need to review your diet and the amount of carbohydrates consumed;
• Eat non-sweet fruits and fiber;
• Remember wholemeal bread, as well as baked potatoes in their skins;
• Constantly replenish your stock of knowledge about health and bodybuilding.

If you stick to these simple rules, then your energy will noticeably increase, and the effectiveness of training will increase.

Instead of a conclusion

As a result, I want to say that you need to approach training intelligently and with knowledge of the matter. That is, you need to remember not only what exercises, how to do them and how many approaches. But also pay attention to nutrition, remember about proteins, fats, carbohydrates and water. After all, it is the combination of proper training and high-quality nutrition that will allow you to quickly achieve your goal - a beautiful athletic body. Products should be not just a set, but a means to achieve the desired result. So think not only in the hall, but also during meals.

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Carbohydrates- organic compounds, the composition of which in most cases is expressed by the general formula C n(H2O) m (n And m≥ 4). Carbohydrates are divided into monosaccharides, oligosaccharides and polysaccharides.

Monosaccharides- simple carbohydrates, depending on the number of carbon atoms, are divided into trioses (3), tetroses (4), pentoses (5), hexoses (6) and heptoses (7 atoms). The most common are pentoses and hexoses. Properties of monosaccharides- easily soluble in water, crystallize, have a sweet taste, can be presented in the form of α- or β-isomers.

Ribose and deoxyribose belong to the group of pentoses, are part of the RNA and DNA nucleotides, ribonucleoside triphosphates and deoxyribonucleoside triphosphates, etc. Deoxyribose (C 5 H 10 O 4) differs from ribose (C 5 H 10 O 5) in that it has a hydrogen atom at the second carbon atom, not a hydroxyl group like ribose.

Glucose, or grape sugar(C 6 H 12 O 6), belongs to the group of hexoses, can exist in the form of α-glucose or β-glucose. The difference between these spatial isomers is that at the first carbon atom in α-glucose the hydroxyl group is located under the plane of the ring, while in β-glucose it is above the plane.

Glucose is:

1. one of the most common monosaccharides,
2. the most important source of energy for all types of work occurring in the cell (this energy is released during the oxidation of glucose during respiration),
3. monomer of many oligosaccharides and polysaccharides,
4. an essential component of blood.

Fructose or fruit sugar, belongs to the group of hexoses, sweeter than glucose, found in free form in honey (more than 50%) and fruits. It is a monomer of many oligosaccharides and polysaccharides.

Oligosaccharides- carbohydrates formed as a result of a condensation reaction between several (from two to ten) monosaccharide molecules. Depending on the number of monosaccharide residues, disaccharides, trisaccharides, etc. are distinguished. Disaccharides are the most common. Properties of oligosaccharides- dissolve in water, crystallize, the sweet taste decreases as the number of monosaccharide residues increases. The bond formed between two monosaccharides is called glycosidic.

Sucrose or cane or beet sugar, is a disaccharide consisting of glucose and fructose residues. Found in plant tissues. It is a food product (common name - sugar). In industry, sucrose is produced from sugar cane (stems contain 10-18%) or sugar beets (root crops contain up to 20% sucrose).

Maltose or malt sugar, is a disaccharide consisting of two glucose residues. Present in germinating seeds of cereals.

Lactose or milk sugar, is a disaccharide consisting of glucose and galactose residues. Present in the milk of all mammals (2-8.5%).

Polysaccharides- these are carbohydrates formed as a result of the polycondensation reaction of a multitude (several tens or more) of monosaccharide molecules. Properties of polysaccharides- do not dissolve or dissolve poorly in water, do not form clearly formed crystals, do not have a sweet taste.

Starch(C 6 H 10 O 5) n is a polymer whose monomer is α-glucose. Starch polymer chains contain branched (amylopectin, 1,6-glycosidic bonds) and unbranched (amylose, 1,4-glycosidic bonds) sections. Starch is the main reserve carbohydrate of plants, is one of the products of photosynthesis, accumulates in seeds, tubers, rhizomes, bulbs. The starch content in rice grains is up to 86%, wheat - up to 75%, corn - up to 72%, in potato tubers - up to 25%. Starch is the main carbohydrate human food (digestive enzyme - amylase).

Glycogen(C 6 H 10 O 5) n- a polymer, the monomer of which is also α-glucose. The polymeric chains of glycogen resemble the amylopectin sections of starch, but unlike them, they branch even more strongly. Glycogen is the main reserve carbohydrate of animals, in particular humans. Accumulates in the liver (content - up to 20%) and muscles (up to 4%), is a source of glucose.

(C 6 H 10 O 5) n is a polymer whose monomer is β-glucose. Cellulose polymer chains do not branch (β-1,4-glycosidic bonds). The main structural polysaccharide of plant cell walls. The cellulose content in wood is up to 50%, in the fibers of cotton seeds - up to 98%. Cellulose is not broken down by human digestive juices, because. it lacks the enzyme cellulase, which breaks bonds between β-glucoses.

Inulin is a polymer whose monomer is fructose. Reserve carbohydrate of plants of the Compositae family.

Glycolipids- complex substances formed as a result of the combination of carbohydrates and lipids.

Glycoproteins- complex substances formed as a result of the combination of carbohydrates and proteins.

Functions of carbohydrates

The structure and function of lipids

Lipids do not have a single chemical characteristic. In most benefits, giving lipid determination, they say that this is a combined group of water-insoluble organic compounds that can be extracted from the cell with organic solvents - ether, chloroform and benzene. Lipids can be divided into simple and complex.

Simple lipids in the majority are esters of higher fatty acids and trihydric alcohol glycerol - triglycerides. Fatty acid have: 1) the same grouping for all acids - a carboxyl group (-COOH) and 2) a radical by which they differ from each other. The radical is a chain of various numbers (from 14 to 22) groups -CH 2 -. Sometimes the fatty acid radical contains one or more double bonds (-CH=CH-), such fatty acid is called unsaturated. If a fatty acid has no double bonds, it is called rich. In the formation of triglyceride, each of the three hydroxyl groups of glycerol undergoes a condensation reaction with a fatty acid to form three ester bonds.

If triglycerides are dominated by saturated fatty acids, then at 20°C they are solid; they are called fats, they are characteristic of animal cells. If triglycerides are dominated by unsaturated fatty acids, then at 20 °C they are liquid; they are called oils, they are characteristic of plant cells.

1 - triglyceride; 2 - ester bond; 3 - unsaturated fatty acid;
4 - hydrophilic head; 5 - hydrophobic tail.

The density of triglycerides is lower than that of water, so they float in water, are on its surface.

Simple lipids also include waxes- esters of higher fatty acids and macromolecular alcohols (usually with an even number of carbon atoms).

Complex lipids. These include phospholipids, glycolipids, lipoproteins, etc.

Phospholipids- triglycerides in which one fatty acid residue is replaced by a phosphoric acid residue. They take part in the formation of cell membranes.

Glycolipids- see above.

Lipoproteins- complex substances formed as a result of the combination of lipids and proteins.

Lipoids- fat-like substances. These include carotenoids (photosynthetic pigments), steroid hormones (sex hormones, mineralocorticoids, glucocorticoids), gibberellins (plant growth substances), fat-soluble vitamins (A, D, E, K), cholesterol, camphor, etc.

Functions of lipids

Function	Examples and explanations
Energy	The main function of triglycerides. When splitting 1 g of lipids, 38.9 kJ are released.
Structural	Phospholipids, glycolipids and lipoproteins are involved in the formation of cell membranes.
Reserve	Fats and oils are a reserve food substance in animals and plants. Important for animals that hibernate during the cold season or make long transitions through areas where there are no food sources. Plant seed oils are needed to provide energy to the seedling.
Protective	Layers of fat and fatty capsules provide shock absorption of internal organs. Layers of wax are used as a water-repellent coating in plants and animals.
Thermal insulation	Subcutaneous fatty tissue prevents the outflow of heat into the surrounding space. Important for aquatic mammals or mammals living in cold climates.
Regulatory	Gibberellins regulate plant growth. The sex hormone testosterone is responsible for the development of male secondary sexual characteristics. The sex hormone estrogen is responsible for the development of female secondary sexual characteristics and regulates the menstrual cycle. Mineralocorticoids (aldosterone, etc.) control water-salt metabolism. Glucocorticoids (cortisol, etc.) are involved in the regulation of carbohydrate and protein metabolism.
Source of metabolic water	When 1 kg of fat is oxidized, 1.1 kg of water is released. Important for desert dwellers.
catalytic	Fat-soluble vitamins A, D, E, K are enzyme cofactors, i.e. by themselves, these vitamins do not have catalytic activity, but without them, enzymes cannot perform their functions.

Go to lectures number 1"Introduction. Chemical elements of the cell. Water and other inorganic compounds"

Go to lectures №3“The structure and function of proteins. Enzymes»