Plant cell wall formation carbohydrates or lipids. Carbohydrates, lipids. Biopolymers. Structure and function of lipids
The mass fraction of carbohydrates in living nature is greater than that of other organic compounds. In the cells of animals and fungi, carbohydrates are contained in insignificant amounts (about 1% of dry mass, in liver and muscle cells - up to 5%), while in plant cells their content is much higher (60 - 90%). Carbohydrates are formed primarily through 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 or more. However, there are carbohydrates in which this ratio is slightly different, and some contain nitrogen, phosphorus or sulfur atoms.
Carbohydrates include monosaccharides, oligosaccharides, and polysaccharides.
Monosaccharides are highly soluble in substances and have a sweet taste. Let's 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 by the number of carbon atoms in their molecules. The most important for wildlife are pentose (compounds with five carbon atoms) and hexose (compounds with six carbon atoms). Apart from glucose, common hexoses are fructose and galactose. Of the pentoses, ribose and deoxyribose are widespread, the residues of which are part of the monomers of nucleic acids. Monosaccharides are able to combine with each other using -OH groups. In this case, it is formed between two residues of monosaccharides through the oxygen atom (-O-).
Diagram of the formation of polysaccharides using cellulose as an example (molecule fragment) Oligosaccharides and polysaccharides are composed of monosaccharide residues. Oligosaccharides are polymeric carbohydrates in which from 2 to 10 monosaccharide units are linked by covalent bonds. For example, disaccharides are formed by two monosaccharide residues. The following disaccharides are common in nature: 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 - polysaccharides - can be formed. These compounds are poorly soluble in water and have no sweet taste. In nature, common polysaccharides formed from glucose residues are cellulose, glycogen and starch. Another naturally occurring polysaccharide, chitin, consists of nitrogen-containing glucose derivatives.
The functions of carbohydrates are quite varied. 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 largest amount of energy is released as a result of the oxidation of carbohydrates with oxygen, but 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 lack of oxygen.
Polysaccharides can accumulate in cells, that is, perform a reserve function. Glycogen accumulates in the cells of animals and fungi, and starch in plant cells. The building (structural) function of carbohydrates is that polysaccharides are part of certain structures. So, chitin forms the outer skeleton of arthropods and is contained in the cell wall of fungi, and cellulose - in the cell wall of plants. Carbohydrates bound to and lipids are located outside the plasma membrane of the animal cell and the bacterial cell wall. 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, lubricate the surfaces of the joints.
Polysaccharide chains can be linearly spaced or branched, depending on their function. The chains of polysaccharides, which are part of the structures of a cell or organism, are connected by numerous bonds with each other, which ensures the strength and chemical resistance of these substances. However, most polysaccharides are reserve substances of animal and plant cells, have numerous branched chains, as a result of which these molecules in the cell are rapidly degraded to glucose at many points simultaneously.
Structure, properties and biological role of lipids
Each cell of 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 an unbranched chain. Some lipids have a slightly different structure, but also poorly soluble in water.
Lipids are hydrophobic, but they dissolve well in non-polar solvents: benzene, chloroform, acetone.
Fats constitute a large group of lipids. Fats are esters of a trihydric alcohol of glycerol and three residues of unbranched fatty acids. 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 consists in the fact that fats are contained in the cytoplasm of cells in the form of inclusions - in fat cells, sunflower seeds, etc. Fat reserves can be used by organisms as reserve nutrients and as a source of metabolic water (when 1 g of fat is oxidized, about 1.1 ml of water).
Accumulating in the subcutaneous fatty tissue of animals, fats protect the body from 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 have a protective function. In particular, they protect internal organs from mechanical damage.
Compounds similar to fats in structure 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 body surface.
Steroids form a separate group of lipids. The most important steroid in the animal body is cholesterol - a component of cell membranes, as well as a precursor for the synthesis of vitamin D, adrenal hormones and gonads.
Among lipids, there are compounds formed as a result of the interaction of molecules of simple lipids with other substances. These include lipoproteins (compounds of lipids and proteins), glycolipids (lipids and carbohydrates), phospholipids (containing phosphoric 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 nature to living, are studied by scientists at the molecular level. And learn the composition, structure and function of carbohydrates, lipids
SUBSTANCES in 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 matter These are chemical compounds that contain carbon atoms. Characteristic only for living organisms Organic substances fats proteins carbohydrates (lipids) nucleic acids
Biopolymers Organic compounds having big sizes called macromolecules. Macromolecules, consist of repeating, structurally similar low molecular weight compounds linked 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 monomeric 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 apparent repeatability of monomers ... A-B-A-A-B-A-B-B-B-A ... A-B-C-B-B-C-A-C-A-A-C
Properties of biopolymers Biopolymers Number, composition, order of monomers Construction of many variants of molecules The basis of 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 molecules of organic substances:
CARBOHYDRATES Cells C, O, H C n (H 2 O) n P - 70-90% F - 1-2% of dry weight 1-2% C 5 H 10 O 5 C 3 H 6 O 3 C 6 H 12 О 6 С 4 Н 8 О 4 Formed from water (Н 2 О) and carbon dioxide (СО 2) during photosynthesis in chloroplasts of green plants
Mono - Oligo (di) - Poly - S A X A R I D S C 3 Trioses (PVC, milk to-that) 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) CARBOHYDRATES SIMPLE COMPLEX All carbohydrates have a carbonyl group:
Linear form Fruktoza Glucoza MONOSACCHARIDES: Properties: Colorless, sweet, soluble, crystallize, pass through membranes EASILY Monosaccharide molecules are linear chains of carbon atoms. Cyclic form in solution 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. In solutions they take a cyclic form Are a part of nucleic acids
Colorless Sweet Soluble DISACHARIDES: Sugar (glucose + fructose) Malt (glucose + glucose) Lactose (glucose + galactose) Properties:
POLYSACCHARIDES: Cellulose The molecules have a linear (unbranched) structure, as a result of which cellulose easily forms fibers. Insoluble in water and has no sweet taste. The walls of plant cells are made of it. Performs 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 The molecule consists of approximately 30,000 glucose residues. It resembles starch in structure, but is more branched and dissolves better 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 enters the cell membranes (C 8 H 13 O 5 N)
The building shell made 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 from large moisture loss. FUNCTIONS OF CARBOHYDRATES
Structural Monosugar 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 through the body, and therefore are unsuitable for long-term storage. The role of energy storage is played by huge water-insoluble polysaccharide molecules. Plants have starch, and 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 sugar polymers that are part of cell membranes; they ensure the interaction of cells of the same type, recognition of each other by cells. (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 unite into one group, and liver cells - into another). FUNCTIONS OF CARBOHYDRATES
Energetic (17.6 kJ) Mono - and oligosaccharides are an important source of energy for any cell. When they split, they release energy, which is stored in the form of ATP molecules, which are used in many vital 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, the penetration of harmful bacteria and viruses.
CARBOHYDRATES C, O, H COMPLEX Mono - Oligo (di) - Poly - S A X A R I D S Trioses (PVC, milk to-ta) 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. through the membranes EASILY tasteless dissolve crystallize through the membranes NOT at
С, О, Н alcohol (glycerol) fatty acids + HYDROPHOBIC DISSOLVE IN GASOLINE, ETHER, CHLOROFORM 5-10%, in fat cells up to 90% PROPERTIES: LIPIDS
PHOSPHOLIPIDS STEROIDS LIPOPROTEINS GLYCOLIPIDS WAX TRIGLYCERIDES LIPIDS Types of lipids
FATS (solid) OILS (liquid) TRIGLYCERIDES Alcohol glycerin + fatty acids Alcohol + unsaturated (saturated) fatty acids Types of lipids
PHOSPHOLIPIDS Glycerin + fatty acids + phosphoric acid residue CELL MEMBRANES Lipid types
Esters of higher fatty acids and monohydric high molecular alcohols WAX Plant Animals Types of lipids
STEROIDS VITAMINS (K, E, D, A) HORMONES (adrenal glands, sex) Alcohol cholesterol + fatty acids Types of lipids
LIPOPROTEINS GLYCOLIPIDS Lipids + carbohydrates Lipids + proteins Types of lipids Almost all lipoproteins are produced in the liver. The main function of lipoproteins is to transport lipid components to tissues. They are localized mainly on the outer surface of the plasma membrane, where their carbohydrate components are among other carbohydrates on the cell surface. can participate in intercellular interactions and contacts. Some of them are antigens.
FUNCTIONS OF LIPIDS Storage
SUPPORTING-STRUCTURAL FUNCTIONS OF LIPIDS Lipids take part 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 required by the body. During the oxidation of 1 g of fat, 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) are able to 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 LIPIDS Mechanical (shock absorption, fatty layer abdominal protects internal organs from damage) Thermoregulatory (heat-insulating) - fat poorly conducts heat and cold. Electrical insulating (myelin sheath of nerve fibers)
Source of metabolic water FUNCTIONS OF LIPIDS When 1 kg of fat breaks down, 1.1 kg of water is released
LIPIDS C, O, H alcohol (glycerin) fatty acids + HYDROPHOBIC 5-10%, in fat cells up to 90% FATS (solid) OILS (liquid) PHOSPHO-LIPIDS STEROIDS LIPOPROTEINS GLYCOLIPIDS -FUNCTIONS- FATS + TRIGLIC ACIDS Alcohol + unsaturated (saturated) fatty acids Alcohol + unsaturated fatty acids Glycerin + fatty acids + phosphoric acid residue Esters of higher fatty acids and monohydric high molecular alcohols WAX Lipids + carbohydrates Lipids + proteins Alcohol cholesterol + fatty acids, VITAMINS (A E, K) HORMONES (adrenal glands, sex) Support-structural Regulatory (hormonal) Energetic 39.1 kJ Catalytic Reserved 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 (H 2 O) m (n and m ≥ 4). Carbohydrates are classified into monosaccharides, oligosaccharides, and polysaccharides.
Monosaccharides - simple carbohydrates, depending on the number of carbon atoms, are subdivided into trioses (3), tetroses (4), pentose (5), hexose (6) and heptose (7 atoms). The most common are pentoses and hexoses. Properties of monosaccharides - easily dissolve 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 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, and in β-glucose, above the plane.
Glucose is:
- one of the most common monosaccharides,
- the most important source of energy for all types of work taking place in the cell (this energy is released during the oxidation of glucose during respiration),
- monomer of many oligosaccharides and polysaccharides,
- an essential component of the blood.
Fructose, or fruit sugar, belongs to the group of hexoses, is sweeter than glucose, is 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. The most common are disaccharides. Properties of oligosaccharides - dissolve in water, crystallize, 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. Contained 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 beet (root crops contain up to 20% sucrose).
Maltose, or malt sugar, Is a disaccharide consisting of two glucose residues. It is present in germinating seeds of cereals.
Lactose, or milk sugar, Is a disaccharide consisting of glucose and galactose residues. It is present in the milk of all mammals (2-8.5%).
Polysaccharides - these are carbohydrates formed as a result of the polycondensation reaction of many (several tens or more) monosaccharide molecules. Polysaccharide properties - do not dissolve or poorly dissolve in water, do not form clearly shaped crystals, do not have a sweet taste.
Starch (C 6 H 10 O 5) n - a polymer, the monomer of which is α-glucose. Polymer starch chains contain branched (amylopectin, 1,6-glycosidic bonds) and unbranched (amylose, 1,4-glycosidic bonds) sites. Starch is the main reserve carbohydrate of plants, is one of the products of photosynthesis, accumulates in seeds, tubers, rhizomes, and 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 polymer chains of glycogen resemble the amylopectin regions of starch, but unlike them, they branch even more. Glycogen is the main reserve carbohydrate in animals, in particular humans. It 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 - polymer, the monomer of which is β-glucose. Polymer chains of cellulose 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 cellulase enzyme that breaks bonds between β-glucose.
Inulin - polymer, the monomer of which is fructose. Reserve carbohydrate of plants of the Asteraceae 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
Structure and function of lipids
Lipids do not have a single chemical characteristic. In most benefits, giving determination of lipids, it is said that this is a collection group of water-insoluble organic compounds that can be removed from the cell with organic solvents - ether, chloroform and benzene. Lipids can be roughly divided into simple and complex.
Simple lipids the majority are represented by esters of higher fatty acids and trihydric alcohol of 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 varying numbers (from 14 to 22) —CH 2 - groups. Sometimes a fatty acid radical contains one or more double bonds (-CH \u003d CH-), such fatty acid is called unsaturated... If a fatty acid has no double bonds, it is called saturated... During 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 link; 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 high molecular weight 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 - fatty 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.
Lipid functions
| Function | Examples and explanations |
|---|---|
| Energy | The main function of triglycerides. When 1 g of lipids are broken down, 38.9 kJ is released. |
| Structural | Phospholipids, glycolipids and lipoproteins are involved in the formation of cell membranes. |
| Storing | Fats and oils are a reserve food substance in animals and plants. It is important for animals hibernating during the cold season or making long transitions through an area where there are no food sources. Plant seed oils are essential to provide energy to the seedling. |
| Protective | Fat layers and fat capsules provide cushioning of internal organs. Wax layers are used as water-repellent coating in plants and animals. |
| Heat insulating | Subcutaneous adipose tissue prevents the outflow of heat into the surrounding space. Important for aquatic mammals or mammals in colder climates. |
| Regulatory | Gibberellins regulate plant growth. The sex hormone testosterone is responsible for the development of male secondary sex characteristics. The sex hormone estrogen is responsible for the development of female secondary sexual characteristics and regulates the menstrual cycle. Mineralocorticoids (aldosterone and others) 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 cofactors of enzymes, 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 - organic matter, which include carbon, oxygen, 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 in liver and muscle cells - up to 5%. Plant cells are 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, in contrast to complex ones, which decompose during 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 the molecule of monosaccharides, there are: trioses (3C), tetroses (4C), pentose (5C), hexose (6C), heptose ( 7C). In nature, the most widespread are pentoses and hexoses. AT
Figure: ... 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
Figure: ... 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. Part of complex carbohydrates. Mandatory blood component. A decrease in its amount leads to immediate disruption of the vital functions of nerve and muscle cells. Being in cells, it regulates osmotic pressure. Fructose found in free form in fruits. It is especially abundant in honey and fruits. Much sweeter than glucose and other sugars. It is a part of oligo- and polysaccharides, participates in maintaining the turgor of plant cells. Galactose - also the spatial isomer of glucose. Together with glucose they form the most important milk disaccharide - lactosecalled milk sugar... Easily converted to glucose. M
Figure: ... Isomers of glucose:
1 - -isomer; 2 - -isomer.
Olecules of monosaccharides can have the form of rectilinear 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 plane of the cycle (-isomer) and above it (-isomer),-isomers form starch and glycogen molecules, -isomers form cellulose. Properties of monosaccharides: low molecular weight, sweet taste, easily dissolves in water, crystallizes, refers to reducing (restoring) sugars. Complex carbohydrates.Complex carbohydrates are called carbohydrates, the molecules of which decompose during hydrolysis to form monosaccharides. Their composition is expressed by the general formula Cm (H 2 O) n, where m\u003e n. Complex carbohydrates are divided into oligosaccharides and polysaccharides.ABOUT
Figure: ... Disaccharide formation.
Ligosaccharides . Oligosaccharides are complex carbohydrates containing from 2 to 10 monosaccharide residues. Depending on the number of monosaccharide residues included in oligosaccharide molecules, disaccharides, trisaccharides, tetrasaccharides, etc. are distinguished. Disaccharides are the most widespread 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 arising between two monosaccharides is called glycosidic... It usually forms between the 1st and 4th carbon atoms of adjacent monosaccharide units - 1,4-glycosidic bond... The most important disaccharides are maltose, lactose, sucrose. Maltose (malt sugar) consists of two -glucose residues. The disaccharide is readily soluble in water. 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) consists of-glucose and fructose residues. Let's easily dissolve in water. Widely distributed in plants. Carbohydrates formed during photosynthesis flow out of the leaves in the form of sucrose... Sucrose is readily converted to starch and glycogen. Plays a huge role in the nutrition of animals and humans. Sucrose is mainly obtained from sugar beets and sugar cane.
Figure: ... The most important disaccharides
Lactose (milk sugar) formed by residues galactose and -glucose... Poorly soluble in water. Part of milk. It is a source of energy for young mammals. 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, monomers of which are simple carbohydrates. Most often, the monomer of polysaccharides is glucose, sometimes galactose and other sugars. As a rule, the composition of polysaccharides contains several hundred monomeric units. P
Fig. 267. Formation of a branched polysaccharide.
Olisaccharides are formed as a result of the 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 the monosaccharide residues that make up the different linear chains. The most important polysaccharides are starch, glycogen, cellulose, chitin, murein. Starch - the main reserve carbohydrate of plants. General formula (C 6 H 10 O 5) n, where n is the number of -glucose residues. Insoluble in cold water... In hot water, it forms a solution resembling colloidal (starch paste) in properties. The starch molecule consists of about 20% amylose and 80% of amylopectin... Linear amylose chains consist of several thousand glucose residues and are capable of spiral coiling, taking on a more compact form. Amylopectin branches intensively, and due to this, its compactness is ensured.
Figure: ... Formation of a triglyceride molecule.
Most of the 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, they distinguish saturated fatty acidsthat do not contain 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 ones are liquid ( oil). 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 weight alcohols. They are found both in the animal and plant kingdoms, where they perform mainly protective functions. In plants, for example, they cover the leaves, stems and fruits with a thin layer, protecting them from being wetted by water and the penetration of microorganisms. The shelf life of the fruit depends on the quality of the wax coating. Under the cover of beeswax, honey is stored and larvae develop. To complex lipids include phospholipids, g
Figure: 269. Phospholipid Molecule
Lipids, lipoproteins, steroids, steroid hormones, vitamins A, D, E, K. F
Figure: ... Phospholipid acid
membrane-forming
Ospholipids are esters of polyhydric alcohols with higher fatty acids containing a phosphoric acid residue (Fig.). Sometimes additional groups (nitrogenous bases, amino acids) can be associated with it. As a rule, the phospholipid molecule contains 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 always directed to the outer and inner surfaces of the membrane, and hydrophobic tails are directed towards each other inside the membrane. Glycolipids Are carbohydrate derivatives of lipids. Along with polyhydric alcohol and higher fatty acids, their molecules also include carbohydrates. They are localized mainly on the outer surface of the plasma membrane, where their carbohydrate components are among the other carbohydrates on the cell surface. Lipoproteins - lipid molecules associated with proteins. There are a lot of them in membranes, proteins can penetrate the membrane through and through, are located under or above the membrane, they can be immersed in the lipid bilayer to different depths. Lipoids - fatty substances. These include steroids (widespread in animal tissues cholesterol and its derivatives - hormones of the adrenal cortex - mineralocorticoids, glucocorticoids, estradiol and testosterone - respectively female and male sex hormones). Lipoids include terpenes ( essential oils, on which the smell of plants depends), gibberellins (plant growth substances), some pigments (chlorophyll, bilirubin), fat-soluble vitamins (A, D, E, K). Lipid functions.
| Examples and explanations |
|
| Energy | The main function of triglycerides. When 1 g of lipids are broken down, 38.9 kJ is released |
| Structural | Phospholipids, glycolipids and lipoproteins are involved in the formation of cell membranes. |
| Storing | Fats and oils are a reserve food substance in animals and plants. Important for animals hibernating during the cold season or making long transitions through an area where there are no food sources Plant seed oils are essential to provide energy to the seedling. |
| Protective | Fat layers and fat capsules provide cushioning of internal organs. Wax layers are used as a water-repellent coating in plants and animals. |
| Heat insulating | Subcutaneous adipose tissue prevents the outflow of heat into the surrounding space. Important for aquatic mammals or mammals in colder climates. |
| Regulatory | Gibberellins regulate plant growth. The sex hormone testosterone is responsible for the development of male secondary sex characteristics. The sex hormone estrogen is responsible for the development of female secondary sexual characteristics and regulates the menstrual cycle. Mineralocorticoids (aldosterone and others) 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 cofactors of enzymes, that is, 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 the depressing data on the health status of modern schoolchildren, the lack of a food culture as a component of a healthy lifestyle.
1. Characteristics of carbohydrates Carbohydrates, or saccharides, organic substances, which include carbon, oxygen, hydrogen. Carbohydrates make up about 1% of the dry matter mass in animal cells, and in liver and muscle cells up to 5%. Plant cells are the richest in carbohydrates (up to 90% of dry weight). 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 the molecule, monosaccharides are distinguished: trioses (3C), tetroses (4C), pentose (5C), hexose (6C), heptose (7C). Complex carbohydrates Complex carbohydrates are carbohydrates, the molecules of which decompose 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 the remains of simple sugars. Simple carbohydrates are called monosaccharides. General formula of simple sugars (CH 2 O) n, where n 3 1. Characteristics of carbohydrates
Monosaccharide properties: low molecular weight; sweet taste; easily soluble in water; crystallize; refer to reducing (restoring) sugars. The most important monosaccharides: Pentoses of ribose and deoxyribose, 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 ribose. 1. Characteristics of carbohydrates
The most common hexoses are glucose, fructose and galactose (general formula C 6 H 12 O 6). Glucose (grape sugar). It is found in free form in both plants and animals. Glucose is the primary energy source for cells. Fructose. Widely distributed in nature. It is found in free form in fruits. It is especially abundant in honey and fruits. Much sweeter than glucose and other sugars. It is a part of oligo- and polysaccharides, participates in maintaining the turgor of plant cells. Since fructose metabolism is not regulated by insulin, it has essential when feeding 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 plane of the cycle (-isomer) and above it (-isomer). 1. Characteristics of carbohydrates
N. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. Oligosaccharides. Oligos "title \u003d" (! LANG: Complex carbohydrates are carbohydrates whose molecules decompose during hydrolysis to form simple carbohydrates. Their composition is expressed by the general formula C m (H 2 O) n, where m\u003e n. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. Oligosaccharides. Oligos" class="link_thumb"> 6 !} Complex carbohydrates are those whose molecules break down during hydrolysis to form simple carbohydrates. Their composition is expressed by the general formula C m (H 2 O) n, where m\u003e n. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. Oligosaccharides. Oligosaccharides are complex carbohydrates containing from 2 to 10 monosaccharide residues. Depending on the number of monosaccharide residues included in oligosaccharide molecules, disaccharides, trisaccharides, tetrasaccharides, etc. are distinguished. Disaccharides are the most widespread in nature. Oligosaccharides have good water solubility, they crystallize easily, have, as a rule, a sweet taste, and can be both reducing and non-reducing. 1. Characteristics of carbohydrates n. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. Oligosaccharides. Oligos "\u003e n. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. Oligosaccharides. Oligosaccharides are complex carbohydrates containing from 2 to 10 monosaccharide residues. Depending on the number of monosaccharide residues included in oligosaccharide molecules, disaccharides, trisaccharides, etc., are distinguished. Disaccharides are the most widespread in nature. Oligosaccharides have good solubility in water, they crystallize easily, have, as a rule, sweet taste, can be both reducing and non-reducing. 1. Characteristics of carbohydrates "\u003e n. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. Oligosaccharides. Oligos "title \u003d" (! LANG: Complex carbohydrates are carbohydrates whose molecules decompose during hydrolysis to form simple carbohydrates. Their composition is expressed by the general formula C m (H 2 O) n, where m\u003e n. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. Oligosaccharides. Oligos"> title="Complex carbohydrates are those whose molecules break down during hydrolysis to form simple carbohydrates. Their composition is expressed by the general formula C m (H 2 O) n, where m\u003e n. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. Oligosaccharides. Oligos"> !}
Disaccharides are formed as a result of the condensation of two monosaccharides (most often hexoses). The bond that occurs between two monosaccharides is called glycosidic. It is usually formed between the 1st and 4th carbon atoms of adjacent monosaccharide units (1,4-glycosidic bond). 1. Characteristics 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 (storage carbohydrate in plants); o glycogen (storage carbohydrate of animals); o cellulose (plant cell wall); o chitin (fungal cell wall); o murein (bacterial cell wall). 1. Characteristics of carbohydrates
Starch and glycogen molecules consist of β-glucose residues, cellulose from α-glucose residues. In addition, the chains do not branch in cellulose, and in glycogen they branch more strongly than in starch. With an increase in the amount of monomers, the solubility of polysaccharides decreases and the sweet taste disappears. 1. Characteristics 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. Characteristics 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 a source of energy. Increased breakdown of carbohydrates occurs, for example, during seed germination, intense muscle work, prolonged fasting. 1. Characteristics 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, 2040% of the plant cell wall material is cellulose, and cotton fibers are almost pure cellulose, which is why they are used to make tissues. 1. Characteristics of carbohydrates
What elements are included in carbohydrates? What is the general carbohydrate formula? Carbon, hydrogen and oxygen. C x (H 2 O) y, where x y. What classes of carbohydrates are distinguished? There are three main classes of carbohydrates: simple - monosaccharides, and complex - oligosaccharides and polysaccharides. What are the most important monosaccharides: From monosaccharides greatest value for living organisms have ribose, deoxyribose, glucose, fructose, galactose. What are the most important disaccharides: Sucrose (cane sugar), maltose (malt sugar), lactose (milk sugar). Name the most important polysaccharides: Starch (storage carbohydrate of plants), glycogen (storage carbohydrate of animals), cellulose (cell wall of plants), chitin (cell wall of fungi), murein (cell wall of bacteria). What is the difference between the alpha and beta isomers of glucose? The hydroxyl group at the first carbon atom can be located both under the plane of the cycle (-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 - from chitin, bacteria - from murein. Let's summarize:
Lipids (from the Greek lipos - fat) are an extensive group of fats and fat-like substances that are found in all living cells. Most 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, lipids are very small, only a few percent, but in the cells of the subcutaneous adipose tissue of mammals, their content reaches 90%. In terms of 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 attachment of three residues of high molecular weight fatty acids to one molecule of the trihydric alcohol of glycerol. Among the compounds of this group, there are fats that remain solid at a temperature of 20 ° C, and oils that become liquid under these conditions. Oils are more common in 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 of the fatty acids contain an even number of carbon atoms in the "tail", from 14 to Lipid characteristics
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 distinguish: saturated fatty acids and unsaturated fatty acids having double bonds between carbon atoms (-CH \u003d 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 arise, therefore the resulting compound is called an ester. Usually, all three hydroxyl groups of glycerol react, 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 structurally similar 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 (oxidation of 1 kg of fat produces 1 kg of 100 g of water). This is especially valuable for desert animals living 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 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, about 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, in many vertebrates, the subcutaneous fat layer is well expressed, which allows them to live in cold climates, and in cetaceans it also plays another role - it contributes to buoyancy. Wax plaque on various parts of plants prevents excessive evaporation of water; in animals it acts as a water-repellent coating. 2. Characterization of lipids
Lipids also perform a building function, since 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 well soluble in organic solvents (gasoline, chloroform, ether) .. What can be said about the structure of fats? Fats are composed of three residues of high molecular weight fatty acids attached to one molecule of a trihydric alcohol glycerin. What about phospholipids? Phospholipids are structurally similar 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 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 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 its 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, food contains water. What hormones are lipids? Cortisone, produced by the adrenal cortex, various sex hormones. What lipids perform a building function? Cell membrane components: phospholipids, lipoproteins, glycolipids, cholesterol. Let's summarize:
