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Lipids are a complex mixture of organic compounds found in plants, animals and microorganisms. Their common features are: insolubility in water (hydrophobicity) and good solubility in organic solvents (gasoline, diethyl ether, chloroform, etc.).

Lipids are often divided into two groups: Simple lipids Complex lipids These are lipids, the molecule of which does not contain nitrogen, phosphorus, sulfur atoms. Simple lipids include: higher carboxylic acids; waxes; triol and diol lipids; glycolipids. These are lipids, the molecule of which contains nitrogen and/or phosphorus, as well as sulfur atoms.

The main function of lipids is energy. Lipids are higher in calories than carbohydrates. During the breakdown of 1 g of fat, 38.9 kJ are released. Structural. Lipids take part in the formation of cell membranes. Reserve. This is especially important for animals that hibernate during the cold season or make long transitions through areas where there are no food sources.

Thermoregulatory. Fats are good thermal insulators due to poor heat conduction. They are deposited under the skin, forming thick layers in some animals. For example, in whales, the layer of subcutaneous fat reaches a thickness of 1 m. Protective-mechanical. Accumulating in the subcutaneous layer, fats protect the body from mechanical influences.

Source of metabolic water. One of the products of fat oxidation is water. This metabolic water is very important for desert dwellers. So, the fat with which the camel's hump is filled is primarily not a source of energy, but a source of water.

Increased buoyancy. Fat reserves increase the buoyancy of aquatic animals. For example, thanks to subcutaneous fat, the body of walruses weighs about the same as the water it displaces.

Lipids (fats) are very important in nutrition, because they contain a number of vitamins - A, O, E, K and fatty acids important for the body, which synthesize various hormones. They are also part of the tissue and, in particular, the nervous system.

Certain lipids are directly responsible for increasing blood cholesterol levels. Consider: 1. Fats that raise cholesterol These are saturated fats found in meat, cheese, lard, butter, dairy and smoked products, and palm oil. 2. Fats that contribute little to the formation of cholesterol. They are found in oysters, eggs, and skinless poultry. 3. Fats that lower cholesterol. These are vegetable oils: olive, rapeseed, sunflower, corn and others. Fish oil plays no role in cholesterol metabolism, but prevents cardiovascular disease. Therefore, the following varieties of fish (the most fatty) are recommended: chum and salmon, tuna, mackerel, herring, sardines.

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Carbohydrates, or saccharides, are organic substances that include carbon, oxygen, and hydrogen. The chemical composition of carbohydrates is characterized by their general formula Сm(Н2О)n, where m≥n. The number of hydrogen atoms in carbohydrate molecules is usually twice the number of oxygen atoms (that is, as in a water molecule). Hence the name carbohydrates.

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Properties of monosaccharides: low molecular weight; sweet taste; easily soluble in water; crystallize; are reducing (restoring) sugars.

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Monosaccharide molecules can be in the form of straight chains or cyclic structures.

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Disaccharides (oligosaccharides) The most widely distributed disaccharides in nature are: maltose, consisting of two residues -glucose; lactose - milk sugar (-glucose + galactose); sucrose - beet sugar (-glucose + fructose).

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Disaccharides are formed by the condensation of two monosaccharides (most often hexoses). The bond that occurs between two monosaccharides is called a glycosidic bond. It is usually formed between the 1st and 4th carbon atoms of adjacent monosaccharide units (1,4-glycosidic bond).

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Polysaccharides Properties of polysaccharides: large molecular weight (usually hundreds of thousands); do not give clearly formed crystals; either insoluble in water, or form solutions resembling colloidal properties; sweet taste is not characteristic;

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Functions of carbohydrates: Energy. One of the main functions of carbohydrates. Carbohydrates are the main sources of energy in the animal body. When splitting 1 g of carbohydrate, 17.6 kJ is released. С6Н12О6 + О2 = 6СО2 + 6Н2О + 17.6 kJ It is expressed in the accumulation of starch by plant cells and glycogen by animal cells. Support and construction. Carbohydrates are part of cell membranes and cell walls (glycocalix, cellulose, chitin, murein). Combined with lipids and proteins, they form glycolipids and glycoproteins.

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Ribose and deoxyribose are part of the monomers of DNA, RNA and ATP nucleotides. Receptor. Oligosaccharide fragments of glycoproteins and glycolipids of cell walls perform a receptor function. 6. Protective. Mucus secreted by various glands is rich in carbohydrates and their derivatives (for example, glycoproteins). They protect the esophagus, intestines, stomach, bronchi from mechanical damage, prevent the penetration of bacteria and viruses into the body.

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Lipids Lipids are a group of organic compounds that do not have a single chemical characteristic. They are united by the fact that they are all derivatives of higher fatty acids, insoluble in water, but highly soluble in organic solvents (ether, chloroform, gasoline).

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Depending on the structural features of the molecules, there are: Simple lipids, which are two-component substances that are esters of higher fatty acids and any alcohol. Complex lipids having multicomponent molecules: phospholipids, lipoproteins, glycolipids. Lipoids, which include steroids - polycyclic alcohol cholesterol and its derivatives.

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simple lipids. Fats. Fats are widely distributed in nature. They are part of the human body, animals, plants, microbes, some viruses. The content of fats in biological objects, tissues and organs can reach 90%. Fats are esters of higher fatty acids and trihydric alcohol - glycerol. In chemistry, this group of organic compounds is called triglycerides. Triglycerides are the most abundant lipids in nature.

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Waxes are a group of simple lipids, which are esters of higher fatty acids and higher high molecular weight alcohols. Waxes are found in both the animal and vegetable kingdoms, where they perform mainly protective functions. In plants, for example, they cover leaves, stems and fruits with a thin layer, protecting them from wetting with water and the penetration of microorganisms. The shelf life of fruits depends on the quality of the wax coating. Honey is stored under the cover of beeswax and larvae develop. Other types of animal wax (lanolin) protect hair and skin from water.

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complex lipids. Phospholipids are esters of polyhydric alcohols with higher fatty acids containing a phosphoric acid residue. Sometimes additional groupings (nitrogenous bases, amino acids, glycerol, etc.) can be associated with it. Lipoproteins are derivatives of lipids with various proteins. Some proteins penetrate the membrane - integral proteins, others are immersed in the membrane to different depths - semi-integral proteins, and others are located on the outer or inner surface of the membrane - peripheral proteins.

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Glycolipids are carbohydrate derivatives of lipids. The composition of their molecules, along with polyhydric alcohol and higher fatty acids, also includes carbohydrates (usually glucose or galactose). They are localized predominantly on the outer surface of the plasma membrane, where their carbohydrate components are among other cell surface carbohydrates.

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Lipoids Lipoids are fat-like substances. These include steroids (cholesterol, which is widespread in animal tissues, its derivatives - estradiol and testosterone - female and male sex hormones, respectively), terpenes (essential oils on which the smell of plants depends), gibberellins (plant growth substances), some pigments (chlorophyll , bilirubin), some vitamins (A, D, E, K), etc.

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Functions of lipids. The main function of lipids is energy. Lipids are higher in calories than carbohydrates. During the breakdown of 1 g of fat to CO2 and H2O, 38.9 kJ are released. Structural. Lipids take part in the formation of cell membranes. The membranes contain phospholipids, glycolipids, lipoproteins. Reserve. This is especially important for animals that hibernate during the cold season or make long transitions through areas where there are no food sources. The seeds of many plants contain the fat needed to provide energy to the developing plant. Thermoregulatory. Fats are good thermal insulators due to poor thermal conductivity. They are deposited under the skin, forming thick layers in some animals. For example, in whales, the layer of subcutaneous fat reaches a thickness of 1 m. Protective-mechanical. Accumulating in the subcutaneous layer, fats protect the body from mechanical influences.

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catalytic. This function is associated with fat-soluble vitamins (A, D, E, K). By themselves, vitamins do not have catalytic activity. But they are coenzymes; without them, enzymes cannot perform their functions. Source of metabolic water. One of the products of fat oxidation is water. This metabolic water is very important for desert dwellers. So, the fat with which the camel's hump is filled is primarily not a source of energy, but a source of water (when 1 kg of fat is oxidized, 1.1 kg of water is released). Increased buoyancy. Fat reserves increase the buoyancy of aquatic animals.

Characteristics of lipids Lipids are a combined group of organic compounds that do not have a single chemical characteristic. They are united by the fact that they are all derivatives of higher fatty acids, insoluble in water, but highly soluble in organic solvents (ether, chloroform, gasoline). Lipids are found in all cells of animals and plants. The content of lipids in cells is 1 - 5% of dry mass, but in adipose tissue it can sometimes reach 90%.

Characteristics of lipids Depending on the structural features of the molecules, there are: Simple lipids, which are two-component substances that are esters of higher fatty acids and any alcohol. Complex lipids having multicomponent molecules: phospholipids, lipoproteins, glycolipids. Lipoids, which include steroids - polycyclic alcohol cholesterol and its derivatives.

Characterization of lipids Simple lipids. 1. Fats. Fats are widely distributed in nature. They are part of the human body, animals, plants, microbes, some viruses. The content of fats in biological objects, tissues and organs can reach 90%. Fats are esters of higher fatty acids and the trihydric alcohol glycerol. In chemistry, this group of organic compounds is called triglycerides. Triglycerides are the most abundant lipids in nature.

Characterization of lipids Usually, all three hydroxyl groups of glycerol react, so the reaction product is called a triglyceride. Physical properties depend on the composition of their molecules. If saturated fatty acids predominate in triglycerides, then they are solid (fats), if unsaturated liquid (oils). The density of fats is lower than that of water, so they float in water and are on the surface.

Characteristics of lipids Complex lipids: Phospholipids, glycolipids, lipoproteins, lipoids 1. Phospholipids. As a rule, a phospholipid molecule has two higher fatty acid residues and one phosphoric acid residue. Phospholipids are found in both animals and plants. Phospholipids are present in all cells of living beings, participating mainly in the formation of cell membranes.

Characteristics of lipids 2. Lipoproteins are derivatives of lipids with various proteins. Some proteins penetrate the membrane - integral proteins, others are immersed in the membrane to different depths - semi-integral proteins, and others are located on the outer or inner surface of the membrane - peripheral proteins. 3. Glycolipids are carbohydrate derivatives of lipids. The composition of their molecules, along with phospholipids, also includes carbohydrates. 4. Lipoids are fat-like substances. These include sex hormones, some pigments (chlorophyll), some vitamins (A, D, E, K).

Functions of lipids 1. The main function of lipids is energy. Lipids are higher in calories than carbohydrates. During the breakdown of 1 g of fat to CO 2 and H 2 O, 38.9 kJ are released. 2. Structural. Lipids take part in the formation of cell membranes. The membranes contain phospholipids, glycolipids, lipoproteins. 3. Spare. This is especially important for animals that hibernate during the cold season or make long transitions through areas where there are no food sources. The seeds of many plants contain the fat needed to provide energy to the developing plant.

4. Thermoregulatory. Fats are good thermal insulators due to poor thermal conductivity. They are deposited under the skin, forming thick layers in some animals. For example, in whales, the layer of subcutaneous fat reaches a thickness of 1 m. 5. Protective-mechanical. Accumulating in the subcutaneous layer, fats protect the body from mechanical influences. Functions of lipids

6.Catalytic. This function is associated with fat-soluble vitamins (A, D, E, K). By themselves, vitamins do not have catalytic activity. But they are coenzymes; without them, enzymes cannot perform their functions. 7. Source of metabolic water. One of the products of fat oxidation is water. This metabolic water is very important for desert dwellers. So, the fat with which the camel's hump is filled is primarily not a source of energy, but a source of water (when 1 kg of fat is oxidized, 1.1 kg of water is released). 8. Increasing buoyancy. Fat reserves increase the buoyancy of aquatic animals. Functions of lipids

Test 1. With the complete combustion of 1 g of the substance, 38.9 kJ of energy was released. This substance refers to: 1. Carbohydrates. 2. To fats. 3. Or to carbohydrates, or to lipids. 4. To proteins. Test 2. The basis of cell membranes is formed by: 1. Fats. 2. Phospholipids. 3.Wax. 4. Lipids. Test 3. Statement: "Phospholipids esters of glycerol (glycerol) and fatty acids": True. Wrong. Repetition:

**Test 4. Lipids perform the following functions in the body: 1.Structural.5. Some are enzymes. 2. Energy.6. Source of metabolic water 3. Heat-insulating.7. Reserve. 4.Some are hormones.8. These include vitamins A, D, E, K. ** Test 5. A fat molecule consists of residues: 1. Amino acids. 2.Nucleotides. 3.Glycerin. 4.Fatty acids. Test 6. Glycoproteins are a complex: 1. Proteins and carbohydrates. 2.Nucleotides and proteins. 3.Glycerin and fatty acids. 4.Carbohydrates and lipids. Repetition:

LECTURE PLAN Lipid Chemistry 1. Definition, role, classification. 2. Characterization of simple and complex lipids. DIGESTION OF LIPID IN THE GIT 1. The role of lipids in nutrition. 2. Bile acids. Emulsification. 3. Enzymes. 5. Absorption of hydrolysis products. 6. Features in children. 7. Resynthesis. DIGESTION AND ABSORPTION Steatorrhea. Steatorrhea.

Functions of lipids: Substrate-energy Substrate-energy Structural (a component of biomembranes) Structural (a component of biomembranes) Transport (lipoproteins) Transport (lipoproteins) Transmission of a nerve impulse Transmission of a nerve impulse low thermal conductivity) Protective Protective Hormonal Hormonal Vitamin Vitamin

By chemical structure 1. Simple: 1) triacylglycerols (neutral fat) - TG, TAG 1) triacylglycerols (neutral fat) - TG, TAG 2) waxes 2) waxes 2. Complex: 1) phospholipids - PL 1) phospholipids - PL a ) glycerophospholipids a) glycerophospholipids b) sphingophospholipids b) sphingophospholipids 2) glycolipids - GL (cerebrosides, gangliosides, sulfatides) 2) glycolipids - GL (cerebrosides, gangliosides, sulfatides) 3) steroids (sterols and sterides) 3) steroids (sterols and sterides ) In relation to water 1. Hydrophobic (form a film on the surface of the water) - TG 2. Amphiphilic form: a) bilipid layer - PL, GL (1 head, 2 tails) a) bilipid layer - PL, GL (1 head, 2 tail) b) micelle - MG, Xs, VFA (1 head, 1 tail) b) micelle - MG, Xs, VFA (1 head, 1 tail) By biological role 1. reserve (TG) 2. structural - form biological membranes (FL, GL, Xs)

Unsaturated (unsaturated) general formula C n H (2n + 1) -2m COOH Monounsaturated: palmitooleic (16:1) C 15 H 29 COOH oleic (18:1) C 17 H 33 COOH Polyunsaturated (vitamin F): linoleic (18 :2) C 17 H 31 COOH linoleic (18:2) C 17 H 31 COOH (ω-6) linolenic (18:3) C 17 H 29 COOH linolenic (18:3) C 17 H 29 COOH (ω-3 ) arachidonic (20:4) C 19 H 31 COOH arachidonic (20:4) C 19 H 31 COOH (ω-6)

The role of polyunsaturated fatty acids (PUFAs) 1. precursors of eicosanoids (prostaglandins, thromboxanes, leukotrienes) - biologically active substances synthesized from PUFAs with 20 carbon atoms that act as tissue hormones. 2. are part of phospholipids, glycolipids. 3. contribute to the removal of cholesterol from the body. 4. They are vitamin F (omega 3, omega 6).

Human fat = glycerol + 2 unsaturated + 1 saturated HFA (dioleopalmitin) Animal fat = glycerol + 1 unsaturated + 2 saturated HFAs (oleopalmitostearin glycerol + 1 unsaturated + 2 saturated HFAs (oleopalmitostearin) Vegetable fat = glycerol + 3 unsaturated HFAs (triolein) formulas of a molecule of neutral fat of vegetable, animal and human origin independently.

Lysophospholipids Lysophosphatidylcholine (lysolecithin) Contains a free hydroxyl group at the 2nd atom of glycerol. Formed by the action of phospholipase A 2. The membranes in which lysophospholipids are formed become permeable to water, so the cells swell and collapse. (Hemolysis of erythrocytes when bitten by snakes whose venom contains phospholipase A 2)

II. DIGESTION OF LIPID IN THE GIT 1. The role of lipids in nutrition 1. The role of lipids in nutrition 2. Bile acids: formation, structure, paired bile acids, role. 2. Bile acids: formation, structure, paired bile acids, role. 3. Scheme of emulsification. 3. Scheme of emulsification. 4. Enzymes of digestion: pancreatic lipase, the chemistry of the action of lipase on triglyceride; phospholipases, cholesterol esterase. 4. Enzymes of digestion: pancreatic lipase, the chemistry of the action of lipase on triglyceride; phospholipases, cholesterol esterase. 5. Absorption of lipid hydrolysis products. 5. Absorption of lipid hydrolysis products. 6. Features of lipid digestion in children. 6. Features of lipid digestion in children. 7. Resynthesis of triglycerides and phospholipids in the intestinal wall. 7. Resynthesis of triglycerides and phospholipids in the intestinal wall. III. DIGESTION AND ABSORPTION 1. Steatorrhea: causes, types (hepatogenic, pancreatogenic, enterogenic).

ROLE OF LIPID IN NUTRITION 1. Dietary lipids are 99% triglycerides. 2. Lipids come with such food products as vegetable oil - 98%, milk - 3%, butter %, etc. 3. Daily requirement for lipids = 80 g / day (50 g animal + 30 g grow). 4. Due to fats, % of the daily energy requirement is provided. 5. An indispensable component of nutrition - polyunsaturated fatty acids (essential), the so-called. vitamin F is a complex of linoleic, linolenic and arachidonic acids. Daily requirement of vitamin F = 3-16 g. 6. Dietary lipids serve as solvents for fat-soluble vitamins A, D, E, K. 7. High consumption of saturated fats increases the risk of atherosclerosis. Therefore, with age, animal fats are replaced with vegetable ones. 8. Increase the palatability of food and provide saturation.

DIGESTION OF LIPID IN THE GIT In the oral cavity are not digested. They are not digested in the oral cavity. In the stomach only in children (gastric lipase acts only on emulsified milk fats, optimum pH 5.5-7.5). In the stomach only in children (gastric lipase acts only on emulsified milk fats, optimum pH 5.5-7.5). In the small intestine: 1) emulsification, In the small intestine: 1) emulsification, 2) enzymatic hydrolysis. 2) enzymatic hydrolysis. Emulsifying factors 1. bile acids 2. CO2 3. fiber 4. peristalsis 5. polysaccharides 6. fatty acid salts (so-called soaps)

The mechanism of emulsification is to reduce the surface tension of a fat droplet The mechanism of emulsification is to reduce the surface tension of a fat droplet The purpose of emulsification is to increase the area of ​​contact of fat molecules with enzyme molecules The purpose of emulsification is to increase the area of ​​contact of fat molecules with enzyme molecules Emulsification scheme:

BILE ACIDS are derivatives of cholanic acid Formed in the liver from cholesterol Formed in the liver from cholesterol Secreted with bile Secreted with bile Circulate up to 10 times Circulate up to 10 times VZhK, MG, Xs, vitamins A, D, E, K)

Pancreatic lipase Optimum pH 7-8 Optimum pH 7-8 Activated by bile acids Activated by bile acids Only acts on emulsified fats (at the fat/water interface) Only acts on emulsified fats (at the fat/water interface)

ABSORPTION OF FOOD LIPID HYDROLYSIS PRODUCTS 1. IN THE COMPOSITION OF CHOLEIN COMPLEXES (MICELLES): - HFA (with more than 10 carbon atoms) - HFA (with more than 10 carbon atoms) - monoacylglycerides - monoacylglycerides - cholesterol - cholesterol - fat-soluble vitamins A, D, E, K - fat-soluble vitamins A, D, E, K 2. Diffusion: glycerol, VFA (with less than 10 carbon atoms). 3. Pinocytosis.

DIGESTION AND ABSORPTION Always accompanied by steatorrhea - the detection of undigested neutral fat in the feces. Types of steatorrhea: 1. Hepatogenic (in diseases of the liver) - emulsification is disturbed in obstructive jaundice, hepatitis, cirrhosis, congenital atresia of the biliary tract. There are a lot of triglycerides in the feces, a high concentration of high-fat salts (soaps), especially calcium ones. Cal is acholichen (little bile pigments). 2. Pancreatogenic (in diseases of the pancreas) - hydrolysis is disturbed in chronic pancreatitis, congenital hypoplasia, cystic fibrosis. There is a high concentration of triglycerides in feces, low fatty acids, at normal pH and content of bile acids.

3. Enterogenic - the absorption of fat hydrolysis products is impaired in diseases of the small intestine, extensive resection of the small intestine, amyloidosis, a-beta-lipoproteinemia. In feces, the content of high-fat fatty acids sharply increases, the pH shifts to the acid side, bile pigments are normal.

Triacylglycerols (triglycerides, neutral fats) are esters of the trihydric alcohol glycerol and high fatty acids. The role of TG: energy (storage), heat-insulating, shock-absorbing (mechanical protection). Glycerin General formula of fat VFA (3 molecules) Complex ester bond - 3 H 2 O esterification

Lysophospholipids Lysophosphatidylcholine (lysolecithin) Contains a free hydroxyl group at the 2nd atom of glycerol. Formed by the action of phospholipase B (A 2). The membranes in which lysophospholipids are formed become permeable to water, so the cells swell and collapse. (Hemolysis of erythrocytes when bitten by snakes whose venom contains phospholipase B)

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