Formation of the wall of plant cells carbohydrates or lipids. Carbohydrates, lipids. Biopolymers. The structure and function of lipids
The mass fraction of carbohydrates in wildlife is greater than other organic compounds. In the cells of animals and fungi, carbohydrates are contained in a small amount (about 1% of dry weight, in the cells of the liver and muscles - up to 5%), while in plant cells their content is much higher (60 - 90%). Carbohydrates are formed mainly as a result of photosynthesis. Heterotrophic organisms obtain carbohydrates from food or synthesize them from other organic compounds (fats, amino acids, etc.).
Carbohydrates are organic compounds in which the ratio of carbon, oxygen basically corresponds to the formula (CH 2 O) n, where n \u003d 3 and more. However, there are carbohydrates in which this ratio is somewhat different, and some contain nitrogen, phosphorus or sulfur atoms.
Carbohydrates include monosaccharides, oligosaccharides and polysaccharides.
Monosaccharides - highly soluble in substances, have a sweet taste. Consider the structure of monosaccharides using glucose as an example. Its molecular formula is C 6 H 12 0 6 .
Glucose molecule
Monosaccharides are classified according to the number of carbon atoms in their molecules. The most important for wildlife are pentoses (compounds with five carbon atoms) and hexoses (compounds with six carbon atoms). Common hexoses, in addition to glucose, are fructose and galactose. Of the pentoses, ribose and deoxyribose are common, the residues of which are part of the nucleic acid monomers. Monosaccharides are able to combine with each other using -OH groups. In this case, it is formed between two monosaccharide residues through an oxygen atom (-O-).
Scheme of the formation of polysaccharides on the example of cellulose (a fragment of a molecule) Oligosaccharides and polysaccharides are composed of monosaccharide residues. Oligosaccharides are polymeric carbohydrates in which from 2 to 10 monosaccharide units are connected by covalent bonds. For example, disaccharides are formed by two monosaccharide residues. In nature, such disaccharides are common: common food sugar - sucrose (consists of glucose and fructose residues) and milk sugar - lactose (consists of glucose and galactose residues).
As a result of the interaction of monosaccharides, chains of hundreds and thousands of residues can be formed - polysaccharides. These compounds are poorly soluble in water and do not have a sweet taste. In nature, polysaccharides formed from glucose residues are common, these are cellulose, glycogen and starch. Another common polysaccharide in nature, chitin, consists of nitrogen-containing derivatives of glucose.
The functions of carbohydrates are quite diverse. The energy function is due to the fact that as a result of the complete breakdown of 1 g of carbohydrates, 17.6 kJ of energy is released. Part of this energy ensures the functioning of the body, and part is released in the form of heat. The greatest amount of energy is released as a result of the oxidation of carbohydrates with oxygen, however, the breakdown of carbohydrates with the release of energy can occur in other cases. This is important for organisms that exist in conditions of lack or absence of oxygen.
Polysaccharides can accumulate in cells, that is, they can perform a reserve function. Glycogen accumulates in animal and fungal cells, and starch accumulates in plant cells. The construction (structural) function of carbohydrates is that polysaccharides are part of certain structures. So, chitin forms the external skeleton of arthropods and is contained in the cell wall of fungi, and cellulose is found in the cell wall of plants. Carbohydrates associated with and lipids are located outside the plasma membrane of the animal cell and the cell wall of bacteria. Special compounds of carbohydrates with proteins (mucopolysaccharides) perform the function of lubrication in the organisms of vertebrates and humans - they are part of the liquid, lubricates the surfaces of the joints.
Polysaccharide chains can be linear in space or branch, which is associated with their functions. The chains of polysaccharides, which are part of the structures of a cell or organism, are interconnected by numerous bonds, which ensures the strength and chemical resistance of these substances. However, most polysaccharides are reserve substances of animal and plant cells, they have numerous branched chains, as a result of which these molecules are quickly broken down into glucose in the cell at many points simultaneously.
Structure, properties and biological role of lipids
Every cell in the body contains lipids. Lipids are derivatives of fatty acids and polyhydric alcohols or aldehydes. Fatty acids are organic acids with a chain of four or more (up to 24) carbon atoms, usually a straight chain. Some lipids have a slightly different structure, but are also poorly soluble in water.
Lipids are hydrophobic, but dissolve well in non-polar solvents: benzene, chloroform, acetone.
A large group of lipids are fats. Fats are esters of the trihydric alcohol glycerol and three unbranched fatty acid residues. One of the most important functions of fats is energy. In the case of complete breakdown of 1 g of fat, 38.9 kJ of energy is released - twice as much as for the complete breakdown of a similar amount of carbohydrates or proteins. The reserve function is that fats are contained in the cytoplasm of cells in the form of inclusions - in adipose cells, sunflower seeds, etc. Fat reserves can be used by organisms as a reserve nutrients and as a source of metabolic water (when 1 g of fat is oxidized, about 1.1 ml of water is formed).
Accumulating in the subcutaneous adipose tissue of animals, fats protect the body from the effects of sudden changes in temperature, performing a heat-insulating function. This function of fats is due to their low thermal conductivity. Fat reserves in the body can also perform a protective function. In particular, they protect internal organs from mechanical damage.
Compounds similar in structure to fats are waxes, a layer of which covers the leaves and fruits of terrestrial plants, the surface of the chitinous skeleton of many arthropods, preventing excessive evaporation of water from the surface of the body.
Steroids form a separate group of lipids. The most important steroid of the animal organism is cholesterol, a component of cell membranes, as well as a precursor for the synthesis of vitamin D, adrenal and gonadal hormones.
Among lipids, there are compounds formed as a result of the interaction of simple lipid molecules with other substances. These include lipoproteins (compounds of lipids and proteins), glycolipids (lipids and carbohydrates), phospholipids (containing orthophosphoric acid residues)
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Carbohydrates. Lipids Chemical composition cells Luzganova I.N., teacher of biology, MBOU secondary school named after A.M. Gorky, Karachev
Lesson objectives: To find out what processes, which are a qualitative leap from inanimate to living nature, are being investigated by scientists at the molecular level. And to study the composition, structure and functions of carbohydrates, lipids
SUBSTANCES in the composition of the body INORGANIC ORGANIC Compounds Ions Small molecules Macromolecules (biopolymers) Water Salts, acids, etc. Anions Cations Monosaccharides Amino acids Nucleotides Lipids Other Polysaccharides Proteins Nucleic acids
Organic substances These are chemical compounds that contain carbon atoms. Characteristic only for living organisms Organic substances fats proteins carbohydrates (lipids) nucleic acids
Biopolymers Organic compounds that have big sizes called macromolecules. Macromolecules consist of repeating, similar in structure, low molecular weight compounds linked together by a covalent bond - MONOMERS. A macromolecule formed from monomers is called a POLYMER.
Organic compounds that make up living cells are called BIOPOLYMERS. BIOPOLYMERS are linear or branched chains containing many monomer units. Biopolymers
Biopolymers POLYMERS HOMOPOLYMERS HETEROPOLYMERS are represented by one type of monomers (A - A - A - A ...) are represented by several different monomers (A - B - C - A - D ...) REGULAR IRREGULAR group of monomers is periodically repeated ... A-B-A -B-A-B ... ... A-A-B-B-B-A-A-B-B-B ... ... A-B-C-A-B-C-A-B-C ... no visible repeatability of monomers …А-В-А-А-В-А-В-В-В-А... А-В-С-В-В-С-А-С-А-А-С
Properties of biopolymers Biopolymers Number, composition, order of monomers Construction of many variants of molecules Basis for the diversity of life on the planet
Chemical composition Content in the cell Structure (structure) Properties Functions Biopolymers PLAN CHARACTERISTICS:
Organic substances Organic substances fats proteins carbohydrates (lipids) nucleic acids The carbon atoms connected to each other form various structures - the backbone of the molecules of organic substances:
CARBOHYDRATES Cells C, O, H C n (H 2 O) n P - 70-90% W - 1-2% of dry weight 1-2% C 5 H 10 O 5 C 3 H 6 O 3 C 6 H 12 O 6 C 4 H 8 O 4 Formed from water (H 2 O) and carbon dioxide (CO 2) during photosynthesis occurring in the chloroplasts of green plants
Mono– Oligo(di)– Poly– SACHARIDES C 3 Trioses (PVA, lactic acid) C 4 Tetroses C 5 Pentoses (ribose, fructose, deoxyribose) C 6 Hexoses (glucose, galactose) Sucrose (glucose + fructose) Maltose (glucose + glucose) Lactose (glucose + galactose) Starch Cellulose Glycogen Chitin (M) (M + M) (M + M + ... + M) SIMPLE COMPLEX CARBOHYDRATES All carbohydrates have a carbonyl group:
Linear form Fructose Glucose MONOSACCHARIDES: Properties: Colorless, sweet, soluble, crystallize, pass through membranes EASILY Monosaccharide molecules are linear chains of carbon atoms. In solutions, they take a cyclic form Cyclic form Linear form Cyclic form Galactose Are an important source of energy for any cell
Ribose Deoxyribose MONOSACCHARIDES: Properties: Colorless, sweet, soluble, crystallize, pass through membranes EASILY Monosaccharide molecules are linear chains of carbon atoms. Takes a cyclic form in solutions Included in nucleic acids
Colorless Sweet Soluble DISACCHARIDES: S a charose (glucose + fructose) M a l t o s a (glucose + glucose) L a c t o s a (glucose + galactose) Properties:
POLYSACCHARIDES: Cellulose Molecules have a linear (unbranched) structure, as a result of which cellulose easily forms fibers. It is insoluble in water and does not have a sweet taste. It is made up of plant cell walls. Performs a supporting and protective function.
POLYSACCHARIDES: Starch is deposited in the form of inclusions and serves as a reserve energy substance of the plant cell
POLYSACCHARIDES: Glycogen A molecule is made up of approximately 30,000 glucose units. It resembles starch in structure, but is more branched and more soluble in water. It is deposited in the form of inclusions and serves as a reserve energy substance of the animal cell.
POLYSACCHARIDES: Chitin An organic substance from the group of polysaccharides that forms the outer hard cover and skeleton of arthropods, fungi and bacteria and is included in cell membranes (C 8 H 13 O 5 N)
The building envelope of cellulose in plant cells, chitin in the skeleton of insects and in the cell wall of fungi provide cells and organisms with strength, elasticity and protection against large moisture loss. FUNCTIONS OF CARBOHYDRATES
Structural Monosugars can combine with fats, proteins and other substances. For example, ribose is part of all RNA molecules, and deoxyribose is part of DNA. FUNCTIONS OF CARBOHYDRATES
Storage Mono- and oligosaccharides, due to their solubility, are quickly absorbed by the cell, easily migrate throughout the body, and therefore are unsuitable for long-term storage. The role of the energy reserve is played by huge water-insoluble molecules of polysaccharides. Plants have starch, while animals and fungi have glycogen. FUNCTIONS OF CARBOHYDRATES Glycogen in liver cells
Transport In plants, sucrose serves as a soluble reserve saccharide, and a transport form that is easily transported throughout the plant. Signal There are polymers of sugars that are part of cell membranes; they provide interaction of cells of the same type, recognition by cells of each other. (If the separated liver cells are mixed with kidney cells, they will independently disperse into two groups due to the interaction of the same type of cells: kidney cells will join into one group, and liver cells into another). FUNCTIONS OF CARBOHYDRATES
Energy (17.6 kJ) Mono - and oligosaccharides are an important source of energy for any cell. Splitting, they release energy, which is stored in the form of ATP molecules, which are used in many life processes of the cell and the whole organism. FUNCTIONS OF CARBOHYDRATES Protective (“mucus”) Viscous secretions (mucus) secreted by various glands are rich in carbohydrates and their derivatives (for example, glycoproteins). They protect the esophagus, intestines, stomach, bronchi from mechanical damage, penetration of harmful bacteria and viruses.
CARBOHYDRATES C, O, H COMPLEX Mono–Oligo(di)–Poly– SACHAROIDS Trioses (PVC, lactic acid) Tetroses Pentoses (ribose, fructose, deoxyribose) Hexoses (glucose, galactose) Sucrose (glucose+fructose) Maltose (glucose+glucose) Lactose (glucose+galactose) Starch Cellulose Glycogen Chitin sweet soluble crystallize passage. h/w membranes EASILY tasteless dissolve crystallize pass h/w membranes NOT at
С, О, Н alcohol (glycerin) fatty acids + HYDROPHOBIC DISSOLVE IN GASOLINE, ETHER, CHLOROFORM 5-10%, in fat cells up to 90% PROPERTIES: LIPIDS
PHOSPHOLIPIDS STEROIDS LIPOPROTEINS GLYCOLIPIDS TRIGLYCERIDES WAX LIPID Types of lipids
FATS (solid) OILS (liquid) TRIGLYCERIDES Alcohol glycerol + fatty acids Alcohol + unsaturated (saturated) fatty acids Types of lipids
PHOSPHOLIPIDS Glycerol + fatty acids + phosphoric acid residue CELL MEMBRANES Types of lipids
Esters of Higher Fatty Acids and Monohydric High Molecular Alcohols WAX Plant Animals Lipid Species
STEROIDS VITAMINS (K, E, D, A) HORMONES (adrenal, sex) Alcohol cholesterol + fatty acids Types of lipids
LIPOPROTEINS GLYCOLIPIDS Lipids + carbohydrates Lipids + proteins Types of lipids Almost all lipoproteins are formed in the liver. The main function of lipoproteins is the transport of lipid components to tissues. They are localized mainly on the outer surface of the plasma membrane, where their carbohydrate components are among other cell surface carbohydrates. can participate in intercellular interactions and contacts. Some of them are antigens.
FUNCTIONS OF LIPID
Supporting structural function of lipids Lipids are involved in the construction of cell membranes of all organs and tissues, causing their semi-permeability, participate in the formation of many biologically important compounds.
Energy FUNCTIONS OF LIPIDS Lipids account for 25-30% of all energy needed by the body. When 1 g of fat is oxidized, 39.1 kJ of energy is released Fat-soluble vitamins K, E, D, A are coenzymes (non-protein part) of enzymes Catalytic Hormones - steroids (sex, adrenal glands) can change the activity of many enzymes, enhancing or suppressing the action of enzymes and thereby regulating the course of physiological processes in the body Regulatory (hormonal)
Protective FUNCTIONS OF LIPID Mechanical (shock absorption, fat layer abdominal cavity protects internal organs from damage) Thermoregulatory (heat-insulating) - fat does not conduct heat and cold well. Electrical insulating (myelin sheath of nerve fibers)
Source of metabolic water LIPID FUNCTIONS 1 kg of fat breaks down 1.1 kg of water
LIPIDS C, O, H alcohol (glycerol) fatty acids + HYDROPHOBIC 5-10%, in fat cells up to 90% FATS (solid) OILS (liquid) PHOSPHO-LIPIDS STEROIDS LIPOPROTEINS GLYCOLIPIDS-FUNCTIONS-TRIGLYCERIDES Alcohol glycerol + fatty acids Alcohol + unsaturated (limiting) fatty acids Alcohol + unsaturated fatty acids Glycerol + fatty acids + phosphoric acid residue Esters of higher fatty acids and monohydric high molecular weight alcohols WAX Lipids + carbohydrates Lipids + proteins Alcohol cholesterol + fatty acids VITAMINS (A, D. E, K) HORMONES (adrenal glands, sex) Support-structural Regulatory (hormonal) Energetic 39.1 kJ Catalytic Storage Metabolic water source Protective (thermoregulatory) Gasoline, ether, chloroform
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:
- one of the most common monosaccharides,
- 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),
- monomer of many oligosaccharides and polysaccharides,
- 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 fat capsules provide cushioning internal organs. Layers of wax are used as 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, regulates 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. |
Lecture 3. Carbohydrates, lipidsCarbohydrates. Carbohydrates, or saccharides, are organic substances that contain carbon, oxygen, and hydrogen. The chemical composition of carbohydrates is characterized by their general formula C m (H 2 O) n, where m ≥ n. Carbohydrates make up about 1% of the mass of animal cells, and up to 5% in liver and muscle cells. Plant cells are the richest in carbohydrates (up to 90%). 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. There are two groups of carbohydrates: simple and complex. Simple carbohydrates. Simple carbohydrates are called monosaccharides, since they are not hydrolyzed during digestion, unlike complex ones, which decompose upon hydrolysis to form monosaccharides. The general formula of simple sugars is (CH 2 O) n, where n ≥ 3. Depending on the number of carbon atoms in a monosaccharide molecule, there are: trioses (3C), tetroses (4C), pentoses (5C), hexoses (6C), heptoses ( 7C). In nature, pentoses and hexoses are the most widespread. IN
Rice. . Pentoses:
1 - ribose; 2 - deoxyribose.
The most important monosaccharides: from pentoses - ribose (C 5 H 10 O 5) and deoxyribose (C 5 H 10 O 4), which are part of the nucleotides of DNA, RNA and ATP. Deoxyribose differs from ribose in that it has a hydrogen atom at the second carbon atom, and not a hydroxyl group like ribose. AND
Rice. . Linear and cyclic structure of the glucose molecule.
The most common hexoses are glucose, fructose, and galactose ( general formula C 6 H 12 O 6). Glucose (grape sugar) is the primary source of energy for cells. It is part of complex carbohydrates. Mandatory component of blood. A decrease in its amount leads to an immediate disruption of the vital activity of nerve and muscle cells. Being in cells, it regulates osmotic pressure. Fructose found in free form in fruits. Especially a lot of it in honey, fruits. Significantly sweeter than glucose and other sugars. Included in the composition of oligo- and polysaccharides, is involved in maintaining the turgor of plant cells. Galactose is also a spatial isomer of glucose. Together with glucose, they form the most important disaccharide of milk - lactose called milk sugar. Easily converted to glucose. M
Rice. . Glucose isomers:
1 - -isomer; 2 - -isomer.
Monosaccharide molecules can have the form of straight chains or cyclic structures (Fig.). For pentoses and hexoses, it is the cyclic structure that is most characteristic; linear molecules are very rare. Molecules of disaccharides and polysaccharides are also formed by cyclic forms of monosaccharides. Monosaccharides can be presented in the form of - and -isomers (Fig.). The hydroxyl group at the first carbon atom can be located both under the ring plane (-isomer) and above it (-isomer), -isomers form molecules of starch and glycogen, -isomers - cellulose. Properties of monosaccharides: low molecular weight, sweet taste, easily soluble in water, crystallize, are reducing (restoring) sugars. Complex carbohydrates. Complex carbohydrates are called carbohydrates, the molecules of which, during hydrolysis, break down to form monosaccharides. Their composition is expressed by the general formula Сm(H 2 O)n, where m>n. Complex carbohydrates are divided into oligosaccharides And polysaccharides.ABOUT
Rice. . formation of a disaccharide.
Ligosaccharides . Oligosaccharides are complex carbohydrates containing from 2 to 10 monosaccharide residues. Depending on the number of monosaccharide residues included in the oligosaccharide molecules, disaccharides, trisaccharides, tetrasaccharides, etc. are distinguished. Disaccharides are the most widely distributed in nature. disaccharides- oligosaccharides, the molecules of which are formed by two monosaccharide residues. Disaccharides are formed as a result of the condensation of two monosaccharides (most often hexoses) (Fig.). The bond that occurs between two monosaccharides is called glycosidic. Usually it is formed between the 1st and 4th carbon atoms of neighboring monosaccharide units - 1,4-glycosidic bond. The most important disaccharides are maltose, lactose, and sucrose. Maltose (malt sugar) It is made up of two α-glucose residues. The disaccharide is highly soluble in water. It is formed as a result of the condensation reaction of two molecules of -glucose or an enzyme maltase during the hydrolysis of starch. Sucrose (cane, beet sugar) It is made up of α-glucose and fructose residues. Easily soluble in water. Widely distributed in plants. Carbohydrates formed during photosynthesis, in the form of sucrose, flow from the leaves. Sucrose is readily converted to starch and glycogen. It plays a huge role in the nutrition of animals and humans. Sucrose is mainly obtained from sugar beet and sugar cane.
Rice. . The most important disaccharides
Lactose (milk sugar) formed by the remnants galactose and -glucose. Poorly soluble in water. Included in milk. It is a source of energy for young mammals. It is found in free form in some plants. It is used in the microbiological industry for the preparation of nutrient media. Properties of oligosaccharides: relatively low (several hundred) molecular weight, good solubility in water, easy to crystallize, usually have a sweet taste, can be both reducing and non-reducing. Polysaccharides. High molecular weight organic substances, biopolymers, the monomers of which are simple carbohydrates. Most often, the monomer of polysaccharides is glucose, sometimes galactose and other sugars. As a rule, several hundred monomeric units are included in the composition of polysaccharides. P
Fig.267. Formation of a branched polysaccharide.
Olisaccharides are formed as a result of a polycondensation reaction (Fig.). If only 1,4-glycosidic bonds are present in the polysaccharide molecule, then a linear, unbranched polymer (cellulose) is formed. If both 1,4 and 1,6-glycosidic bonds are present, the polymer will be branched (glycogen). A 1,6-glycosidic bond is formed between monosaccharide residues that make up different linear chains. The most important polysaccharides are starch, glycogen, cellulose, chitin, murein. Starch- the main reserve carbohydrate of plants. The general formula is (C 6 H 10 O 5) n, where n is the number of -glucose residues. Insoluble in cold water. IN hot water forms a solution resembling a colloidal (starch paste) in properties. The starch molecule is approximately 20% amylose and 80% of amylopectin. The linear amylose chains consist of several thousand glucose units and are capable of coiling into a more compact form. Amylopectin branches intensively, and due to this, its compactness is ensured.
Rice. . Formation of a triglyceride molecule.
Most fatty acids contain an even number of carbon atoms in the "tail", from 14 to 22 (most often 16 or 18). In addition, the hydrocarbon tail may contain varying amounts of double bonds. By the presence or absence of double bonds in the hydrocarbon tail, saturated fatty acids, not containing double bonds in the hydrocarbon tail and unsaturated fatty acids having double bonds between carbon atoms (-CH \u003d CH-). If saturated fatty acids predominate in triglycerides, then they are solid at room temperature (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. Wax- a group of simple lipids, which are esters of higher fatty acids and higher high-molecular alcohols. They are found both in the animal and plant 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. to complex lipids include phospholipids, g
Rice. 269. Phospholipid molecule
Lycolipids, lipoproteins, steroids, steroid hormones, vitamins A, D, E, K. F
Rice. . Bilayer of phospholipids
membranous
Ospholipids are esters of polyhydric alcohols with higher fatty acids containing a phosphoric acid residue (Fig.). Sometimes additional groupings (nitrogenous bases, amino acids) can be associated with it. As a rule, a phospholipid molecule has two higher fatty acid residues and one phosphoric acid residue. Phospholipids are present in all cells of living beings, participating mainly in the formation of the phospholipid bilayer of cell membranes - phosphoric acid residues are hydrophilic and are always directed towards the outer and inner surface membranes, and hydrophobic tails are directed towards each other inside the membrane. Glycolipids are carbohydrate derivatives of lipids. The composition of their molecules, along with polyhydric alcohol and higher fatty acids, also includes carbohydrates. They are localized predominantly on the outer surface of the plasma membrane, where their carbohydrate components are among other cell surface carbohydrates. Lipoproteins- lipid molecules associated with proteins. There are a lot of them in membranes, proteins can penetrate the membrane through, are located under or above the membrane, can be immersed in the lipid bilayer to different depths. Lipoids- fat-like substances. These include steroids(widespread in animal tissues cholesterol and its derivatives - hormones of the adrenal cortex - mineralocorticoids, glucocorticoids, estradiol and testosterone - female and male sex hormones, respectively). Terpenes are lipoids ( essential oils, on which the smell of plants depends), gibberellins (growth substances of plants), some pigments (chlorophyll, bilirubin), fat-soluble vitamins (A, D, E, K). Functions of lipids.
| 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., these vitamins themselves do not have catalytic activity, but without them, enzymes cannot perform their functions. |
The need to develop materials on nutrition for schoolchildren is dictated by depressing data on the health status of modern schoolchildren, the lack of a food culture as a component healthy lifestyle life.
1. Characteristics of carbohydrates Carbohydrates, or saccharides, organic substances, which include carbon, oxygen, hydrogen. Carbohydrates make up about 1% of the mass of dry matter in animal cells, and up to 5% in liver and muscle cells. Plant cells are the richest in carbohydrates (up to 90% of dry mass). The chemical composition of carbohydrates is characterized by their general formula C m (H 2 O) n, where mn. 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.
Simple Carbohydrates Simple carbohydrates are called monosaccharides. Depending on the number of carbon atoms in a monosaccharide molecule, there are: trioses (3C), tetroses (4C), pentoses (5C), hexoses (6C), heptoses (7C). Complex carbohydrates Complex carbohydrates are carbohydrates whose molecules break down during hydrolysis to form simple carbohydrates. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. There are two groups of carbohydrates: simple sugars and complex sugars formed by residues of simple sugars. Simple carbohydrates are called monosaccharides. The general formula of simple sugars (CH 2 O) n, where n 3 1. Characteristics of carbohydrates
Properties of monosaccharides: low molecular weight; sweet taste; easily soluble in water; crystallize; are reducing (restoring) sugars. The most important monosaccharides: Ribose and deoxyribose pentoses, which are part of DNA, RNA. 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, and not a hydroxyl group like that of ribose. 1. Characterization of carbohydrates
Of the hexoses, the most common are glucose, fructose and galactose (general formula C 6 H 12 O 6). Glucose (grape sugar). It is found free in both plants and animals. Glucose is the primary source of energy for cells. Fructose. Widely distributed in nature. It is found in free form in fruits. Especially a lot of it in honey, fruits. Significantly sweeter than glucose and other sugars. Included in the composition of oligo- and polysaccharides, is involved in maintaining the turgor of plant cells. Because fructose metabolism is not regulated by insulin, importance in the diet of patients with diabetes mellitus. Monosaccharides can be presented in the form of - and -isomers. The hydroxyl group at the first carbon atom can be located both under the ring plane (-isomer) and above it (-isomer). 1. Characterization of carbohydrates
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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 neighboring monosaccharide units (1,4-glycosidic bond). 1. Characterization of carbohydrates
Polysaccharides (Greek poly - many) are polymers and consist of an indefinitely large (up to several hundred or thousands) number of residues of monosaccharide molecules connected by covalent bonds. These include: o starch (reserve carbohydrate of plants); o glycogen (reserve carbohydrate of animals); o cellulose (plant cell wall); o chitin (cell wall of fungi); o murein (cell wall of bacteria). 1. Characterization of carbohydrates
Starch and glycogen molecules consist of α-glucose residues, and cellulose consists of α-glucose residues. In addition, the chains of cellulose do not branch, while those of glycogen branch more strongly than those of starch. With an increase in the amount of monomers, the solubility of polysaccharides decreases and the sweet taste disappears. 1. Characterization of carbohydrates
The main function of carbohydrates is energy. During their enzymatic breakdown and oxidation of carbohydrate molecules, energy is released, which ensures the vital activity of the body. With the complete breakdown of 1 g of carbohydrates, 17.6 kJ are released. 1. Characterization of carbohydrates
Carbohydrates perform a storage function. In excess, they accumulate in the cell as storage substances (starch in plant cells, glycogen in animal cells) and, if necessary, are used by the body as an energy source. Enhanced breakdown of carbohydrates occurs, for example, during seed germination, intense muscular work, and prolonged fasting. 1. Characterization of carbohydrates
The structural or building function of carbohydrates is very important. They are used as building material. Thus, cellulose, due to its special structure, is insoluble in water and has high strength. On average, 20-40% of plant cell wall material is cellulose, and cotton fibers are almost pure cellulose, which is why they are used to make fabrics. 1. Characterization of carbohydrates
What elements are in carbohydrates? What is the general formula for carbohydrates? Carbon, hydrogen and oxygen. C x (H 2 O) y, where x y. What are the classes of carbohydrates? There are three main classes of carbohydrates: simple - monosaccharides, and complex - oligosaccharides and polysaccharides. Name the most important monosaccharides: From monosaccharides highest value for living organisms have ribose, deoxyribose, glucose, fructose, galactose. Name the most important disaccharides: sucrose (cane sugar), maltose (malt sugar), lactose (milk sugar). Name the most important polysaccharides: Starch (plant carbohydrate storage), glycogen (animal storage carbohydrate), cellulose (plant cell wall), chitin (fungal cell wall), murein (bacterial cell wall). What is the difference between alpha and beta glucose isomers? The hydroxyl group at the first carbon atom can be located both under the ring plane (-isomer) and above it (-isomer). Let's summarize:
What is known about the energy function of carbohydrates? This is the main function, with complete oxidation of 1 g, 17.6 kJ is released. Energy. In what form do plants and animals store carbohydrates? Plants are in the form of starch, animals are in the form of glycogen. What is known about the structural function of carbohydrates? The cell wall of plants consists of cellulose, fungi - of chitin, bacteria - of murein. Let's summarize:
Lipids (from the Greek. lipos - fat) - an extensive group of fats and fat-like substances that are found in all living cells. Most of them are non-polar and therefore hydrophobic. They are practically insoluble in water, but highly soluble in organic solvents (gasoline, chloroform, ether, etc.). In some cells, there are very few lipids, only a few percent, but in the cells of the subcutaneous adipose tissue of mammals, their content reaches 90%. By chemical structure lipids are very diverse. 2. Characterization of lipids
1. Simple lipids - fats and waxes. Fats are the simplest and most abundant lipids. Their molecules are formed as a result of the addition of three residues of high molecular weight fatty acids to one molecule of the trihydric alcohol glycerol. Among the compounds of this group, fats are distinguished, which remain solid at a temperature of 20 ° C, and oils, which become liquid under these conditions. Oils are more typical of plants, but can also be found in animals. Fatty acids are a carboxyl group and a hydrocarbon tail, which differs in different fatty acids in the number of -CH 2 groups. The “tail” is non-polar, therefore hydrophobic. Most fatty acids contain an even number of carbon atoms in the "tail", from 14 to Characteristics of lipids
In addition, the hydrocarbon tail may contain varying amounts of double bonds. According to the presence or absence of double bonds in the hydrocarbon tail, they are distinguished: saturated fatty acids and unsaturated fatty acids having double bonds between carbon atoms (-CH=CH-). 2. Characterization of lipids
When a triglyceride molecule is formed, each of the three hydroxyl (-OH) groups of glycerol enters into a condensation reaction with a fatty acid. During the reaction, three ester bonds are formed, so the resulting compound is called an ester. Usually, all three hydroxyl groups of glycerol enter into the reaction, so the reaction product is called 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. 2. Characterization of lipids
2. Complex lipids - phospholipids, glycolipids and lipoproteins. Phospholipids are similar in structure to fats, but in their molecule one or two fatty acid residues are replaced by a phosphoric acid residue. Phospholipids are an integral component of cell membranes. Lipids can form complex connections with substances of other classes, for example, with proteins - lipoproteins and with carbohydrates - glycolipids. 2. Characterization of lipids
3. Steroids are lipids that do not contain fatty acids and have a special structure. Steroids include hormones, in particular cortisone produced by the adrenal cortex, various sex hormones, vitamins A, D, E, K, and plant growth substances. The steroid cholesterol is an important component of cell membranes. 2. Characterization of lipids
Fats are the main storage substance in animals, as well as in some plants. They can also be used as a source of water (when 1 kg of fat is oxidized, 1 kg 100 g of water is formed). This is especially valuable for desert animals that live in conditions of water scarcity. In addition to the water found in food, they use metabolic water. 2. Characterization of lipids
One of the main functions is energy. With the complete oxidation of 1 g of fat, 38.9 kJ of energy is released. That is, fats provide more than 2 times more energy compared to carbohydrates. In vertebrates, approximately half of the energy consumed by cells at rest comes from fat oxidation. 2. Characterization of lipids
Due to their low thermal conductivity, lipids perform a protective function, that is, they serve to insulate organisms. For example, many vertebrates have a well-defined subcutaneous fat layer, which allows them to live in cold climates, while in cetaceans it also plays another role - it contributes to buoyancy. Wax coating on various parts of plants prevents excessive evaporation of water, in animals it plays the role of a water-repellent coating. 2. Characterization of lipids
Lipids also perform a building function, since their insolubility in water makes them the most important components of cell membranes (phospholipids, lipoproteins, glycolipids, cholesterol). Many lipid derivatives (for example, hormones of the adrenal cortex, gonads, vitamins A, D, E, K) are involved in metabolic processes in the body. Therefore, these substances also have a regulatory function. 2. Characterization of lipids
What organic molecules can be called lipids? Substances whose molecules are non-polar and therefore hydrophobic. They are practically insoluble in water, but highly soluble in organic solvents (gasoline, chloroform, ether). What can be said about the structure of fats? Fats are made up of three fatty acid residues attached to one molecule of the trihydric alcohol glycerol. What can be said about phospholipids? Phospholipids are similar in structure to fats, but in their molecule one or two fatty acid residues are replaced by a phosphoric acid residue. Phospholipids are an integral component of cell membranes. What can be said about steroids? Steroids are lipids that do not contain fatty acids and have a special structure. Steroids include hormones, in particular cortisone produced by the adrenal cortex, various sex hormones, vitamins A, D, E, K, and plant growth substances. Let's summarize:
Why are fats the main storage substance in living organisms? With the complete oxidation of 1 g of fat, 38.9 kJ of energy is released. That is, fats provide more than 2 times more energy compared to carbohydrates. A kangaroo rat doesn't drink all his life. How does she do it? Uses metabolic water. When 1 g of fat is oxidized, more than 1 g of water is formed. In addition, water is in food. What hormones are lipids? Cortisone produced by the adrenal cortex, various sex hormones. What lipids perform a building function? Components of cell membranes: phospholipids, lipoproteins, glycolipids, cholesterol. Let's summarize:
