Carbohydrates, their composition and classification. Carbohydrates

Carbohydrates are substances of the composition СmН2nОn, which are of paramount biochemical importance, are widespread in living nature and play big role In human life.

The name carbohydrates arose based on data from the analysis of the first famous representatives this connection group. Substances of this group consist of carbon, hydrogen and oxygen, and the ratio of the numbers of hydrogen and oxygen atoms in them is the same as in water, i.e. For every 2 hydrogen atoms there is one oxygen atom. In the last century they were considered to be carbon hydrates. This is where it came from Russian name carbohydrates, proposed in 1844 by K. Schmidt. The general formula of carbohydrates, according to what has been said, is C m H2 n O n. When “n” is taken out of brackets, the formula C m (H 2 O) n is obtained, which very clearly reflects the name “coal-water”.

The study of carbohydrates has shown that there are compounds that, according to all their properties, should be classified as carbohydrates, although their composition does not exactly correspond to the formula C m H 2n O n. Nevertheless, the ancient name “carbohydrates” has survived to this day, although along with this name, a newer name, glycides, is sometimes used to designate the group of substances under consideration.

The large class of carbohydrates is divided into two groups: simple and complex.

Simple carbohydrates(monosaccharides and monominoses) are carbohydrates that are not capable of hydrolyzing to form simpler carbohydrates; they have the number of carbon atoms equal to the number of oxygen atoms C n H 2n O n.

Complex carbohydrates(polysaccharides or polyoses) are those carbohydrates that can be hydrolyzed to form simple carbohydrates and their number of carbon atoms is not equal to the number of oxygen atoms C m H 2n O n.

The classification of carbohydrates can be depicted in the following diagram:

MONOSACHARIDES, DISACCHARIDES C 12 H 22 O 11, tetrose C 4 H 8 O 4, sucrose, elytrose, lactose, threose, maltose, pentose C 5 H 10 O 5, celobiose, arabinose

POLYSACCHARIDES

Xylose (C 5 H 8 O 4) n ribose pentosans

HEXOSES

C 6 H 12 O 6 (C 6 H 10 O 5) n glucose cellulose mannose starch galactose glycogen fructose

The most important representatives of simple carbohydrates are glucose and fructose; they have the same molecular formula C 6 H 12 O 6.

Glucose is also called grape sugar because it is found in large quantities in grape juice. In addition to grapes, glucose is also found in other sweet fruits and even in different parts plants. Glucose is also widespread in the animal world: 0.1% of it is found in the blood. Glucose is carried throughout the body and serves as a source of energy for the body. It is also part of sucrose, lactose, cellulose, and starch.

Fructose or fruit sugar is widespread in the plant world. Fructose is found in sweet fruits and honey. By extracting juices from flowers of sweet fruits, bees prepare honey, which in chemical composition is mainly a mixture of glucose and fructose. Fructose is also part of complex sugars, such as cane and beet sugars.

Monosaccharides are solid substances that can crystallize. They are hygroscopic, very easily soluble in water, easily form syrups, from which they can be isolated into crystalline form it can be very difficult.

Solutions of monosaccharides have a neutral litmus reaction and have a sweetish taste. The sweetness of monosaccharides varies: fructose is 3 times sweeter than glucose.

Monosaccharides are poorly soluble in alcohol and insoluble in ether.

Monosaccharides, the most important representatives of simple carbohydrates, are found in nature both in a free state and in the form of their anhydrides - complex carbohydrates.

All complex carbohydrates can be considered as anhydrides of simple sugars, obtained by subtracting one or more water molecules from two or more monosaccharide molecules.

Complex carbohydrates include substances with various properties and for this reason they are divided into two subgroups.

1. Sugar-like complex carbohydrates or oligosaccharides. These substances have a number of properties that make them similar to simple carbohydrates.

Sugar-like carbohydrates are easily soluble in water and taste sweet; these sugars are easily obtained in the form of crystals.

When sugar-like polysaccharides are hydrolyzed, each polysaccharide molecule produces a small number of simple sugar molecules - usually 2, 3, or 4 molecules. This is where the second name for sugar-like polysaccharides comes from - oligosaccharides (from the Greek oligos - few).

Depending on the number of monosaccharide molecules that are formed during the hydrolysis of each oligosaccharide molecule, the latter are divided into disaccharides, trisaccharides, etc.

Disaccharides are complex sugars, each molecule of which, upon hydrolysis, breaks down into 2 molecules of monosaccharide.

Methods for the synthesis of disaccharides are known, but practically they are obtained from natural sources.

The most important of the disaccharides, sucrose, is very common in nature. This is the chemical name for the common sugar called cane or beet sugar.

Even 300 years before our era, Hindus knew how to obtain cane sugar from cane. Nowadays, sucrose is obtained from cane growing in the tropics (on the island of Cuba and in other countries of Central America).

In the mid-18th century, the disaccharide was discovered in sugar beets, and in the mid-19th century it was obtained under industrial conditions.

Sugar beets contain 12-15% sucrose, according to other sources 16-20% (sugar cane contains 14-26% sucrose).

Sugar beets are crushed and sucrose is extracted from it hot water in special diffusers. The resulting solution is treated with lime to precipitate impurities, and the excess hydrolysis of calcium that has partially passed into the solution is precipitated by passing carbon dioxide. Then, after separating the precipitate, the solution is evaporated in a vacuum apparatus, obtaining fine-crystalline raw sand. After further purification, refined (purified) sugar is obtained. Depending on the crystallization conditions, it is released in the form of small crystals or in the form of compact “sugar loaves”, which are split or sawn into pieces. Instant sugar is prepared by pressing finely ground granulated sugar.

Cane sugar is used in medicine to make powders, syrups, mixtures, etc.

Beet sugar is widely used in Food Industry, cooking, making wine, beer, etc.

Milk sugar, lactose, is obtained from milk. Milk contains lactose in quite significant quantities: cow's milk 4-5.5% lactose, human milk contains 5.5-8.4% lactose.

Lactose differs from other sugars in that it is not hygroscopic - it does not dampen. This property has great importance: if you need to prepare any powder with sugar that contains an easily hydrolyzing medicine, then take milk sugar. If you take cane or beet sugar, the powder will quickly become damp and the easily hydrolyzing medicinal substance will quickly decompose.

The value of lactose is very high, because she is important nutrient, especially for growing human and mammalian organisms.

Malt sugar is an intermediate product in the hydrolysis of starch. It is also called maltose by another name, because... malt sugar is obtained from starch under the action of malt (in Latin, malt - maltum).

Malt sugar is widely distributed in both plant and animal organisms. For example, it is formed under the influence of enzymes in the digestive canal, as well as many technological processes fermentation industry: distilling, brewing, etc.

The most important polysaccharides are starch, glycogen (animal starch), cellulose (fiber). All three of these higher polyoses consist of residues of glucose molecules, in various ways connected to each other. Their composition is expressed by the general formula (C 6 H 12 O 6) n. The molecular weights of natural polysaccharides range from several thousand to several million.

Starch is the first visible product of photosynthesis. During photosynthesis, starch is formed in plants and deposited in roots, tubers, and seeds. Grains of rice, wheat, rye and other cereals contain 60-80% starch, potato tubers - 15-20%. Starch grains of plants vary in appearance, which is clearly visible when you examine them under a microscope. Appearance starch is well known to everyone: it is white matter, consisting of tiny grains resembling flour, which is why its second name is “potato flour”.

Starch is insoluble in cold water, when hot, it swells and gradually dissolves, forming a viscous solution (paste).

When starch is heated rapidly, the giant starch molecule breaks down into small polysaccharide molecules called dextrins. Dextrins have a common molecular formula with starch (C 6 H 12 O 5) x, the only difference is that “x” in dextrins is less than “n” in starch.

Digestive juices contain several different enzymes that, at low temperatures, hydrolyze starch into glucose:

(C 6 H 10 O 5) > (C 6 H 10 O 5) x > C 12 H 22 O 11 > C 6 H 12 O 6

starch series dextrin maltose glucose

Dextrinization occurs even faster in the presence of acid:

(C 6 H 10 O 5) n + n H 2 O?????> n C 6 H 12 O 6

Enzymatic hydrolysis (decomposition by fermentation) of starch is of industrial importance in the production of ethyl alcohol from grain and potatoes.

The process begins with the conversion of starch into glucose, which is then fermented. Using special yeast cultures and changing conditions, it is possible to direct fermentation towards the production of butyl alcohol, acetone, lactic, citric and gluconic acids.

By subjecting starch to hydrolysis with acids, glucose can be obtained in the form of a pure crystalline preparation or in the form of molasses - a colored non-crystallized syrup.

Starch is of greatest importance as a food product: in the form of bread, potatoes, cereals, being the main source in our diet.

In addition, pure starch is used in the food industry in the production of confectionery and culinary products, and sausages. A significant amount of starch is used for sizing fabrics, paper, cardboard, and the production of office glue.

IN analytical chemistry starch serves as an indicator in the iodometric titration method. For these cases, it is better to use purified amylose, because its solutions do not thicken, and the color formed with iodine is more intense.

In medicine and pharmacy, starch is used to prepare powders, pastes (thick ointments), as well as in the production of tablets.

In the animal world, the role of “spare starch” is played by a polysaccharide related to starch - glycogen. Glycogen is found in all animal tissues.

It is especially abundant in the liver (up to 20%) and muscles (4%).

Glycogen is a white amorphous powder, highly soluble even in cold water. The animal starch molecule is built like amylopectin molecules, differing only in greater branching. The molecular weight of glycogen is in the millions.

Glycogen solutions with iodine give a color ranging from wine-red to red-brown, depending on the origin of the glycogen (animal species) and other conditions.

Glycogen is a reserve nutrient for the body.

Conclusion

I learned a lot about carbohydrates, such as that there are two classes of carbohydrates: simple and complex. The history of the appearance of the name carbohydrates is interesting. I learned that carbohydrates come in different flavors. I realized that life is not possible without carbohydrates; they are present almost everywhere.

Carbohydrates play a primary role in providing energy to the whole body; they take part in the metabolism of all nutrients. They are organic compounds consisting of carbon, hydrogen and oxygen. Carbohydrates, due to their ease of availability and speed of absorption, are the main source of energy for the body.

Carbohydrates can enter the human body from food (cereals, vegetables, legumes, fruits, etc.), and can also be produced from fats and some amino acids.

Classification of carbohydrates

Structurally, carbohydrates are divided into the following groups:

Simple carbohydrates. These include glucose, galactose and fructose (monosaccharides), as well as sucrose, lactose and maltose (disaccharides).

Glucose– the main supplier of energy for the brain. It is found in fruits and berries and is necessary for energy supply and the formation of glycogen in the liver.

Fructose It almost does not require the hormone insulin for its absorption, which allows it to be used for diabetes, but in moderation.

Galactose not found in free form in products. Produced by the breakdown of lactose.

Sucrose found in sugar and sweets. When it enters the body, it is broken down into more components: glucose and fructose.

Lactose– a carbohydrate found in dairy products. With congenital or acquired deficiency of the lactose enzyme in the intestine, the breakdown of lactose into glucose and galactose is impaired, which is known as dairy intolerance. Fermented milk products contain less lactose than milk, since when milk is fermented, lactic acid is formed from lactose.

Maltose- an intermediate product of the breakdown of starch by digestive enzymes. Maltose is subsequently broken down into glucose. It is found in free form in honey, malt (hence the second name – malt sugar) and beer.

Complex carbohydrates. These include starch and glycogen (digestible carbohydrates), as well as fiber, pectins and hemicellulose.

Starch– makes up 80% of all carbohydrates in the diet. Its main sources are bread and baked goods, cereals, legumes, rice and potatoes. Starch is digested relatively slowly, breaking down into glucose.

Glycogen, also called “animal starch,” is a polysaccharide that consists of highly branched chains of glucose molecules. He's not in large quantities found in animal products (in the liver 2-10% and in muscle tissue - 0.3-1%).

Cellulose- This complex carbohydrate, included in the shells plant cells. In the body, fiber is practically not digested; only a small part can be influenced by microorganisms in the intestines.

Fiber, together with pectins, lignins and hemicellulose, is called ballast substances. They improve the functioning of the digestive system, preventing many diseases. Pectins and hemicellulose have hygroscopic properties, which allows them to sorb and carry with them excess cholesterol, ammonia, bile pigments and others harmful substances. Another important benefit of dietary fiber is that it helps prevent obesity. Although they do not have high energy value, vegetables, due to their large amount of dietary fiber, contribute to an early feeling of fullness.

Bread contains large amounts of dietary fiber. coarse, bran, vegetables and fruits.

Glycemic index

Some carbohydrates (simple) are absorbed by the body almost instantly, which leads to a sharp increase in blood glucose levels, while others (complex) are absorbed gradually and do not cause a sharp increase in blood sugar levels. Due to slow absorption, eating foods containing such carbohydrates provides a longer feeling of fullness. This property is used in dietetics for weight loss.

And to estimate the rate of a particular product being broken down in the body, they use glycemic index(GI). This indicator determines the speed at which the product is broken down in the body and converted into glucose. The faster a product breaks down, the higher its glycemic index (GI). Glucose, whose glycemic index (GI) is 100, was taken as the standard. All other indicators are compared with the glycemic index (GI) of glucose. All GI values ​​in various foods can be viewed in a special table of the glycemic index of foods.

Functions of carbohydrates in the body

In the body, carbohydrates perform the following functions:

They are the main source of energy in the body.

Provide all energy expenditures of the brain (the brain absorbs about 70% of the glucose released by the liver)

Participate in the synthesis of ATP, DNA and RNA molecules.

Regulates the metabolism of proteins and fats.

In combination with proteins, they form some enzymes and hormones, secretions of the salivary and other mucus-forming glands, as well as other compounds.

Dietary fiber improves the functioning of the digestive system and removes harmful substances from the body, pectins stimulate digestion.

Lipids- fat-like organic compounds, insoluble in water, but highly soluble in non-polar solvents (ether, gasoline, benzene, chloroform, etc.). Wild ones belong to the simplest biological molecules.

Chemically, most lipids are esters of higher carboxylic acids and a number of alcohols. The most famous among them fats. Each fat molecule is formed by a molecule of the triatomic alcohol glycerol and the ester bonds of three molecules of higher carboxylic acids attached to it. According to the accepted nomenclature, fats are called triacylglycerols.

When fats are hydrolyzed (that is, broken down by the introduction of H + and OH - into ester bonds), they break down into glycerol and free higher carboxylic acids, each containing an even number of carbon atoms.

Carbon atoms in molecules of higher carboxylic acids can be connected to each other by both simple and double bonds. Among the saturated (saturated) higher carboxylic acids most often found in fats are:

palmitic CH 3 - (CH 2) 14 - COOH or C 15 H 31 COOH;

stearic CH 3 - (CH 2) 16 - COOH or C 17 H 35 COOH;

arachine CH 3 - (CH 2) 18 - COOH or C 19 H 39 COOH;

among the unlimited:

oleic CH 3 - (CH 2) 7 - CH = CH - (CH 2) 7 - COOH or C 17 H 33 COOH;

linoleic CH 3 - (CH 2) 4 - CH = CH - CH 2 - CH - (CH 2) 7 - COOH or C 17 H 31 COOH;

linolenic CH 3 - CH 2 - CH = CH - CH 2 - CH = CH - CH 2 - CH = CH - (CH 2) 7 - COOH or C 17 H 29 COOH.

The degree of unsaturation and the length of chains of higher carboxylic acids (i.e., the number of carbon atoms) determines the physical properties of a particular fat.

Fats with short and unsaturated acid chains have a low melting point. At room temperature these are liquids (oils) or ointment-like substances. Conversely, fats with long and saturated chains of higher carboxylic acids are solids at room temperature. This is why, when hydrogenation (saturation of acid chains with hydrogen atoms at double bonds), liquid peanut butter, for example, turns into a homogeneous, spreadable peanut butter, and sunflower oil into margarine. The bodies of animals living in cold climates, such as fish from the Arctic seas, usually contain more unsaturated triacylglycerols than those living in southern latitudes. For this reason, their body remains flexible even at low temperatures.

There are:

Phospholipids- amphiphilic compounds, i.e. they have polar heads and non-polar tails. The groups forming the polar head group are hydrophilic (soluble in water), while the non-polar tail groups are hydrophobic (insoluble in water).

The dual nature of these lipids makes them key role in the organization of biological membranes.

Wax- esters of adnoatomic (with one hydroxyl group) high molecular weight (having a long carbon skeleton) alcohols and higher carboxylic acids.

Another group of lipids consists of steroids. These substances are based on cholesterol alcohol. Steroids are very poorly soluble in water and do not contain higher carboxylic acids.

These include bile acids, cholesterol, sex hormones, vitamin D, etc.

Close to steroids terpenes(plant growth substances - gibberellins; phytol, which is part of chlorophyll; carotenoids - photosynthetic pigments; plant essential oils - menthol, camphor, etc.).

Lipids can form complexes with other biological molecules.

Lipoproteins- complex formations containing triacylglycerols, cholesterol and proteins, the latter not having covalent bonds with lipids.

Glycolipids is a group of lipids built on the basis of the alcohol sphingosine and containing, in addition to the residue of higher carboxylic acids, one or more sugar molecules (most often glucose or galactose).

Functions of lipids

Structural. Phospholipids together with proteins form biological membranes. The membranes also contain sterols.

Energy. When 1 g of fat is oxidized, 38.9 kJ of energy is released, which goes towards the formation of ATP. A significant portion of the body's energy reserves are stored in the form of lipids, which are consumed when there is a lack of nutrients. Hibernating animals and plants accumulate fats and oils and use them to maintain vital processes. The high lipid content in seeds provides energy for the development of the embryo and seedling until it begins to feed itself. The seeds of many plants (coconut palm, castor bean, sunflower, soybean, rapeseed, etc.) serve as raw materials for producing oil industrially.

Protective and thermal insulation. Accumulating in the subcutaneous fatty tissue and around some organs (kidneys, intestines), the fat layer protects the body from mechanical damage. In addition, due to low thermal conductivity, the layer of subcutaneous fat helps retain heat, which allows, for example, many animals to live in cold climates. In whales, in addition, it plays another role - it promotes buoyancy.

Lubricant and water repellent. Waxes cover skin, wool, feathers, make them more elastic and protect them from moisture. The leaves and fruits of plants are covered with a waxy coating; wax is used by bees in the construction of honeycombs.

Regulatory. Many hormones are derivatives of cholesterol, such as sex hormones (testosterone in men and progesterone in women) and corticosteroids (aldosterone).

Metabolic. Cholesterol derivatives, vitamin D play a key role in the metabolism of calcium and phosphorus. Bile acids are involved in the processes of digestion (emulsification of fats) and absorption of higher carboxylic acids.

Lipids are a source of metabolic water. The oxidation of fat produces approximately 105 g of water. This water is very important for some desert inhabitants, in particular for camels, which can do without water for 10-12 days: the fat stored in the hump is used precisely for this purpose. Bears, marmots and other hibernating animals obtain the water they need for life as a result of fat oxidation.

Chemical composition

The cell wall of plant cells consists mainly of polysaccharides. All components that make up the cell wall can be divided into 4 groups:

Structural components represented by cellulose in most autotrophic plants.

Components matrix, i.e. the main substance, shell filler - hemicelluloses, proteins, lipids.

Components, encrusting cell wall (i.e. deposited and lining it from the inside) - lignin and suberin.

Components, adcrusting wall, i.e. deposited on its surface - cutin, wax.

The main structural component of the shell is cellulose is represented by unbranched polymer molecules consisting of 1000-11000 residues - D glucose, interconnected by glycosidic bonds. The presence of glycosidic bonds creates the possibility of the formation of cross-links. Due to this, long and thin cellulose molecules are combined into elementary fibrils or micelles. Each micelle consists of 60-100 parallel cellulose chains. Hundreds of micelles are grouped into micellar rows and form microfibrils with a diameter of 10-15 nm. Cellulose has crystalline properties due to the ordered arrangement of micelles in microfibrils. Microfibrils, in turn, intertwine with each other like strands in a rope and combine into macrofibrils. Macrofibrils are about 0.5 µm thick. and can reach a length of 4 microns. Cellulose has neither acidic nor alkaline properties. It is quite resistant to elevated temperatures and can be heated without decomposition to a temperature of 200 o C. Many of important properties cellulose is due to its high resistance to enzymes and chemical reagents. It is insoluble in water, alcohol, ether and other neutral solvents; does not dissolve in acids and alkalis. Cellulose is perhaps the most common type of organic macromolecule on Earth.

The shell microfibrils are immersed in an amorphous plastic gel - matrix. The matrix is ​​the filler of the shell. The matrix of plant shells includes heterogeneous groups of polysaccharides called hemicelluloses and pectin substances.

Hemicelluloses are branching polymer chains consisting of various hexose residues (D-glucose, D-galactose, mannose),

pentose (L-xylose, L-arabinose) and uric acids (glucuronic and galacturonic). These components of hemicelluloses combine with each other in different quantitative ratios and form various combinations.

Hemicellulose chains consist of 150-300 monomer molecules. They are much shorter. In addition, the chains do not crystallize and do not form elementary fibrils.

That is why hemicelluloses are often called semi-fibers. They account for about 30-40% of the dry weight of cell walls.

In relation to chemical reagents, hemicelluloses are much less resistant than cellulose: they dissolve in weak alkalis without heating; hydrolyze to form sugars in weak acid solutions; Semi-fiber also dissolves in glycerin at a temperature of 300 o C.

Hemicelluloses play a role in the plant body:

Mechanical role, participating along with cellulose and other substances in the construction of cell walls.

The role of reserve substances, deposited and then consumed. In this case, the function of reserve material is predominantly performed by hexoses; and hemicelluloses with mechanical function are usually composed of pentoses. Hemicelluloses are also deposited in the seeds of many plants as reserve nutrients.

Pectic substances have quite complex chemical composition and structure. This is a heterogeneous group that includes branched polymers that carry negative charges due to the many galacturonic acid residues. Characteristic feature: pectin substances swell strongly in water, and some dissolve in it. They are easily destroyed by the action of alkalis and acids.

All cell walls at an early stage of development consist almost entirely of pectin substances. The intercellular substance of the middle plate, as if cementing the shells of the adjacent walls, also consists of these substances, mainly calcium pectate. Pectic substances, although in small quantities, are present in the main thickness of adult cells.

In addition to carbohydrate components, the cell wall matrix also includes a structural protein called extensin. It is a glycoprotein, the carbohydrate part of which is represented by arabinose sugar residues.

The classification of vitamins is based on the principle of their solubility in water and fat.

Water-soluble vitamins: B1 (thiamine), B2 (riboflavin), PP (nicotinic acid), B3 (pantothenic acid), B6 ​​(pyridoxine), B12 (zincobalamin), Bc (folic acid), H (biotin), N (lipoic acid), P (bioflavonoids), C (ascorbic acid) - participate in the structure and functioning of enzymes.

Fat-soluble vitamins: A (retinol), provitamin A (carotene), D (calceferols), E (tocopherols), K (phylloquinones).

Fat-soluble vitamins are included in the structure of membrane systems, ensuring their optimal functional state.

There are also vitamin-like substances: B13 (orotic acid), B15 (pangamic acid), B4 (choline), B8 (inositol), B (carnitine), H1 (paraminbenzoic acid), F (polysaturated fatty acid), U (S=methylmethionine sulfate chloride).

Carbohydrates (sugar A , saccharides) - organic substances containing a carbonyl group and several hydroxyl groups. The name of the class of compounds comes from the words “carbon hydrates” and was first proposed by K. Schmidt in 1844. The appearance of this name is due to the fact that the first of known to science carbohydrates were described by the gross formula C x (H 2 O) y, formally being compounds of carbon and water.

All carbohydrates are made up of individual “units”, which are saccharides. Based on their ability to hydrolyze into monomers, carbohydrates are divided into two groups: simple and complex. Carbohydrates containing one unit are called monosaccharides, two units are disaccharides, two to ten units are oligosaccharides, and more than ten units are polysaccharides. Common monosaccharides are polyoxy-aldehydes (aldoses) or polypoxyketones (ketoses) with a linear chain of carbon atoms (m = 3-9), each of which (except the carbonyl carbon) is linked to a hydroxyl group. The simplest of monosaccharides, glyceraldehyde, contains one asymmetric carbon atom and is known in the form of two optical antipodes (D and L). Monosaccharides quickly increase blood sugar and have a high glycemic index, which is why they are also called fast carbohydrates. They are easily soluble in water and synthesized in green plants. Carbohydrates made up of 3 or more units are called complex carbohydrates. Foods rich in slow carbohydrates gradually increase the glucose content and have a low glycemic index, which is why they are also called slow carbohydrates. Complex carbohydrates are products of polycondensation of simple sugars (monosaccharides) and, unlike simple ones, during the process of hydrolytic cleavage they can decompose into monomers, forming hundreds and thousands of monosaccharide molecules

In living organisms, carbohydrates perform following functions:

1. Structural and support functions. Carbohydrates are involved in the construction of various supporting structures. Thus, cellulose is the main structural component of plant cell walls, chitin performs a similar function in fungi, and also provides rigidity to the exoskeleton of arthropods.

2. Protective role in plants. Some plants have protective formations(thorns, prickles, etc.), consisting of cell walls of dead cells.

3. Plastic function. Carbohydrates are part of complex molecules (for example, pentoses (ribose and deoxyribose) are involved in the construction of ATP, DNA and RNA).

4. Energy function. Carbohydrates serve as a source of energy: the oxidation of 1 gram of carbohydrates releases 4.1 kcal of energy and 0.4 g of water.

5. Storage function. Carbohydrates act as reserve nutrients: glycogen in animals, starch and inulin in plants.

6. Osmotic function. Carbohydrates are involved in the regulation of osmotic pressure in the body. Thus, the blood contains 100-110 mg/% glucose, and the osmotic pressure of the blood depends on the concentration of glucose.

7. Receptor function. Oligosaccharides are part of the receptor portion of many cellular receptors or ligand molecules.

18. Monosaccharides: trioses, tetroses, pentoses, hexoses. Structure, open and cyclic forms. Optical isomerism. Chemical properties glucose, fructose. Qualitative reactions to glucose.

Monosaccharides(from Greek monos- the only one, sacchar- sugar) - the simplest carbohydrates that do not hydrolyze to form simpler carbohydrates - are usually colorless, easily soluble in water, poorly soluble in alcohol and completely insoluble in ether, solid transparent organic compounds, one of the main groups of carbohydrates, the most simple form Sahara. Aqueous solutions have a neutral pH. Some monosaccharides have a sweet taste. Monosaccharides contain a carbonyl (aldehyde or ketone) group, so they can be considered as derivatives of polyhydric alcohols. A monosaccharide with a carbonyl group at the end of the chain is an aldehyde and is called aldose. At any other position of the carbonyl group, the monosaccharide is a ketone and is called ketosis. Depending on the length of the carbon chain (from three to ten atoms) there are trioses, tetroses, pentoses, hexoses, heptoses and so on. Among them, pentoses and hexoses are most widespread in nature. Monosaccharides are the building blocks from which disaccharides, oligosaccharides and polysaccharides are synthesized.

In nature, the most common free form is D-glucose (grape sugar or dextrose, C 6 H 12 O 6) - hexatom sugar ( hexose), structural unit(monomer) of many polysaccharides (polymers) - disaccharides: (maltose, sucrose and lactose) and polysaccharides (cellulose, starch). Other monosaccharides are mainly known as components of di-, oligo- or polysaccharides and are rarely found in the free state. Natural polysaccharides serve as the main sources of monosaccharides.

Qualitative reaction:

Add a few drops of copper (II) sulfate solution and an alkali solution to the glucose solution. No copper hydroxide precipitate is formed. The solution turns bright blue. In this case, glucose dissolves copper (II) hydroxide and behaves like polyhydric alcohol, forming a complex compound.
Let's heat the solution. Under these conditions, the reaction with copper(II) hydroxide demonstrates restorative properties glucose. The color of the solution begins to change. First, a yellow precipitate of Cu 2 O is formed, which over time forms larger red CuO crystals. Glucose is oxidized to gluconic acid.

2HOCH 2 -(CHOH) 4)-CH=O + Cu(OH) 2 2HOCH 2 -(CHOH) 4)-COOH + Cu 2 O↓ + 2H 2 O

19. Oligosaccharides: structure, properties. Disaccharides: maltose, lactose, cellobiose, sucrose. Biological role.

The bulk oligosaccharides represented by disaccharides, including important role For the animal body, sucrose, maltose and lactose play a role. The disaccharide cellobiose has important for plant life.
Disaccharides (bioses) upon hydrolysis form two identical or different monosaccharides. To establish their structure, it is necessary to know from which monosaccharides the disaccharide is built; in what form, furanose or pyranose, is the monosaccharide in the disaccharide; Which hydroxyls are involved in the bonding of two simple sugar molecules?
Disaccharides can be divided into two groups: non-reducing sugars and reducing sugars.
The first group includes trehalose (mushroom sugar). It is incapable of tautomerism: the ester bond between two glucose residues is formed with the participation of both glucosidic hydroxyls
The second group includes maltose (malt sugar). It is capable of tautomerism, since only one of the glucosidic hydroxyls is used to form the ester bond and, therefore, contains in a latent form aldehyde group. The reducing disaccharide is capable of mutarotation. It reacts with reagents on the carbonyl group (similar to glucose), is reduced to a polyhydric alcohol, and oxidized to an acid
Hydroxyl groups of disaccharides undergo alkylation and acylation reactions.
Sucrose(beet, cane sugar). Very common in nature. It is obtained from sugar beets (content up to 28% of dry matter) and sugar cane. It is a non-reducing sugar, since the oxygen bridge is formed with the participation of both glycosidic hydroxyl groups

Maltose(from English malt- malt) - malt sugar, a natural disaccharide consisting of two glucose residues; found in large quantities in sprouted grains (malt) of barley, rye and other grains; also found in tomatoes, pollen and nectar of a number of plants. Maltose is easily absorbed by the human body. The breakdown of maltose into two glucose residues occurs as a result of the action of the enzyme a-glucosidase, or maltase, which is found in the digestive juices of animals and humans, in sprouted grains, in molds and yeast

Cellobiose- 4-(β-glucosido)-glucose, a disaccharide consisting of two glucose residues connected by a β-glucosidic bond; basic structural unit of cellulose. Cellobiose is formed during the enzymatic hydrolysis of cellulose by bacteria living in gastrointestinal tract ruminants. Cellobiose is then broken down by the bacterial enzyme β-glucosidase (cellobiase) into glucose, which ensures the absorption of the cellulose part of the biomass by ruminants.

Lactose(milk sugar) C12H22O11 - a carbohydrate of the disaccharide group, found in milk. The lactose molecule consists of residues of glucose and galactose molecules. Used for cooking nutrient media, for example in the production of penicillin. Used as an excipient (excipient) in the pharmaceutical industry. From lactose, lactulose is obtained - a valuable drug for the treatment of intestinal disorders, such as constipation.

20. Homopolysaccharides: starch, glycogen, cellulose, dextrins. Structure, properties. Biological role. Qualitative reaction to starch.

Homopolysaccharides ( glycans ), consisting of residues of one monosaccharide, can be hexoses or pentoses, that is, hexose or pentose can be used as a monomer. Depending on the chemical nature of the polysaccharide, glucans (from glucose residues), mannans (from mannose), galactans (from galactose) and other similar compounds are distinguished. The group of homopolysaccharides includes organic compounds of plants (starch, cellulose, pectin substances), animals (glycogen, chitin) and bacterial ( dextrans) origin.

Polysaccharides are necessary for the life of animals and plant organisms. This is one of the main sources of energy in the body, generated as a result of metabolism. Polysaccharides take part in immune processes, provide cell adhesion in tissues, and are the bulk of organic matter in the biosphere.

Starch (C 6 H 10 O 5) n - a mixture of two homopolysaccharides: linear - amylose and branched - amylopectin, the monomer of which is alpha-glucose. White amorphous substance, insoluble in cold water, swelling and partially soluble in hot water. Molecular weight 10 5 -10 7 Dalton. Starch, synthesized different plants in chloroplasts, under the influence of light during photosynthesis, differs somewhat in the structure of grains, the degree of polymerization of molecules, the structure of polymer chains and physical and chemical properties. As a rule, the amylose content in starch is 10-30%, amylopectin - 70-90%. The amylose molecule contains on average about 1,000 glucose residues linked by alpha-1,4 bonds. Individual linear sections of the amylopectin molecule consist of 20-30 such units, and at the branching points of amylopectin, glucose residues are connected by interchain alpha-1,6 bonds. With partial acid hydrolysis of starch, polysaccharides of a lower degree of polymerization are formed - dextrins ( C 6 H 10 O 5) p, and with complete hydrolysis - glucose.

Glycogen (C 6 H 10 O 5) n - a polysaccharide built from alpha-D-glucose residues - the main reserve polysaccharide of higher animals and humans, found in the form of granules in the cytoplasm of cells in almost all organs and tissues, however, the largest amount accumulates in muscles and liver. The glycogen molecule is built from branching polyglucoside chains, in the linear sequence of which the glucose residues are connected through alpha-1,4 bonds, and at branching points by interchain alpha-1,6 bonds. The empirical formula of glycogen is identical to the formula of starch. By chemical structure glycogen is close to amylopectin with more pronounced chain branching, and is therefore sometimes called inaccurately “animal starch”. Molecular weight 10 5 -10 8 Dalton and higher. In animal organisms it is a structural and functional analogue of plant polysaccharide - starch. Glycogen forms an energy reserve, which, if necessary, can be quickly mobilized to compensate for a sudden lack of glucose - the strong branching of its molecule leads to the presence large number terminal residues that provide the ability to quickly remove the required number of glucose molecules. Unlike triglyceride (fat) storage, glycogen storage is not as large (calories per gram). Only glycogen stored in liver cells (hepatocytes) can be converted into glucose to power the entire body, and hepatocytes are able to accumulate up to 8 percent of their weight in the form of glycogen, which is the highest concentration of any cell type. The total mass of glycogen in the liver of adults can reach 100-120 grams. In muscles, glycogen is broken down into glucose exclusively for local consumption and accumulates in much lower concentrations (no more than 1% of the total muscle mass), nevertheless total stock in muscles may exceed the reserve accumulated in hepatocytes.

Cellulose(fiber) - the most common structural polysaccharide flora, consisting of alpha-glucose residues presented in beta-pyranose form. Thus, in a cellulose molecule, beta-glucopyranose monomer units are linearly connected to each other by beta-1,4 bonds. With partial hydrolysis of cellulose, the disaccharide cellobiose is formed, and with complete hydrolysis, D-glucose is formed. In the human gastrointestinal tract, cellulose is not digested, since the set of digestive enzymes does not contain beta-glucosidase. However, the presence of an optimal amount of plant fiber in food contributes to the normal formation of feces. Having great mechanical strength, cellulose plays the role of support material plants, for example, in the composition of wood its share varies from 50 to 70%, and cotton is almost one hundred percent cellulose

A qualitative reaction to starch is carried out with an alcohol solution of iodine. When interacting with iodine, starch forms a complex compound of blue-violet color

Based on their ability to hydrolyze, carbohydrates are divided into simple - monosaccharides and complex - polysaccharides. Monosaccharides do not hydrolyze to form simpler carbohydrates. Polysaccharides capable of hydrolysis can be considered as polycondensation products of monosaccharides. Polysaccharides are high-molecular compounds whose macromolecules contain hundreds and thousands of monosaccharide residues. Among them there is a group of oligosaccharides that have a relatively small molecular weight and containing from 2 to 10 monosaccharide residues.

Simple carbohydrates

These include glucose, galactose and fructose (monosaccharides), as well as sucrose, lactose and maltose (disaccharides).
Glucose is the main energy supplier for the brain. It is found in fruits and berries and is necessary for energy supply and the formation of glycogen in the liver.

Fructose almost does not require the hormone insulin for its absorption, which allows it to be used for diabetes, but in moderation.

Galactose is not found in free form in products. Produced by the breakdown of lactose.

Sucrose is found in sugar and sweets. When it enters the body, it is broken down into more components: glucose and fructose.

Lactose is a carbohydrate found in dairy products. With congenital or acquired deficiency of the lactase enzyme in the intestines, the breakdown of lactose into glucose and galactose is impaired, which is known as dairy intolerance. Fermented milk products contain less lactose than milk, since when milk is fermented, lactic acid is formed from lactose.

Maltose is an intermediate product of the breakdown of starch by digestive enzymes. Maltose is subsequently broken down into glucose. It is found in free form in honey, malt (hence the second name – malt sugar) and beer.

Complex carbohydrates

These include starch and glycogen (digestible carbohydrates), as well as fiber, pectins and hemicellulose.

Starch makes up 80% of all carbohydrates in the diet. Its main sources are bread and baked goods, cereals, legumes, rice and potatoes. Starch is digested relatively slowly, breaking down into glucose.

Glycogen, also called “animal starch,” is a polysaccharide that consists of highly branched chains of glucose molecules. It is found in small quantities in animal products (in the liver 2-10% and in muscle tissue - 0.3-1%).

Fiber is a complex carbohydrate that is part of the membranes of plant cells. In the body, fiber is practically not digested; only a small part can be influenced by microorganisms in the intestines.

Fiber, together with pectins, lignins and hemicellulose, is called ballast substances. They improve the functioning of the digestive system, preventing many diseases. Pectins and hemicellulose have hygroscopic properties, which allows them to absorb and carry with them excess cholesterol, ammonia, bile pigments and other harmful substances. Another important benefit of dietary fiber is that it helps prevent obesity. Although they do not have high energy value, vegetables, due to their large amount of dietary fiber, contribute to an early feeling of fullness.

Dietary fiber is found in large quantities in wholemeal bread, bran, vegetables and fruits.

Monosaccharides (monoses)

They are heterofunctional compounds. Their molecules simultaneously contain carbonyl (aldehyde or ketone) and several hydroxyl groups, i.e. monosaccharides are polyhydroxycarbonyl compounds - polyhydroxyaldehydes and polyhydroxyketones. They are characterized by the presence of an unbranched carbon chain.

Using X-ray diffraction analysis, it was established that of the two chair-shaped conformations of the pyranose ring in D-glucopyranose, the one in which all the larger substituents, for example the primary alcohol and hydroxyl groups, occupy equatorial positions is achieved. In this case, the hemiacetal group in the beta anomer is in the equatorial position, and in the alpha anomer in the axial position. Thus, in the beta anomer, all substituents are in a more favorable equatorial position, and therefore it predominates in the mixture of D-glucose tautomers. Anomers are not formed in equal quantities, but with a predominance of the thermodynamically more stable diastereomer. The preference for the formation of one or another anomer is largely determined by their conformational structure. The conformational structure of D-glucopyranose sheds light on the uniqueness of this monosaccharide. Beta-D-glucopyranose is a monosaccharide with a complete equatorial arrangement of substituents. The resulting high thermodynamic stability is the main reason for its widespread occurrence in nature. In lactopyranose, the OH group at C-4 is in the axial position. The ratio of alpha and beta anomers is approximately the same as that of glucopyranose.

Glycosides

When monosaccharides interact with hydroxyl-containing compounds (alcohols, phenols, etc.) under acid catalysis, derivatives of the cyclic form are formed only at the glycosidic OH group - cyclic acetals, called glycosides. A convenient way to obtain glycosides is to pass hydrogen chloride gas (catalyst) through a solution of the monosaccharide in alcohols, such as ethanol, methanol, etc. This produces ethyl or methyl glycosides, respectively. The names of glycosides indicate first the name of the introduced radical, then the configuration of the anomeric center and the name of the carbohydrate residue with the suffix -oside. Like all acetals, glycosides are easily hydrolyzed by dilute acids, but are resistant to hydrolysis in a slightly alkaline environment. For the hydrolytic breakdown of glycosides, enzymatic hydrolysis is widely used, the advantage of which is its specificity. For example, the enzyme alpha-glucosidase from yeast cleaves only the alpha-glucosidic bond; beta-glucosidase from almonds - only beta-glucosidic linkage. On this basis, enzymatic hydrolysis is often used to determine the configuration of the anomeric carbon atom. Hydrolysis of glycosides underlies the hydrolytic breakdown of polysaccharides carried out in the body, and is also used in many industrial processes. A glycoside molecule can formally be represented as consisting of two parts: carbohydrate and aglycone. Monosaccharides themselves can also act as hydroxide-containing aglycones. Glycosides formed with OH-containing aglycones are called O-glycosides. In turn, glycosides formed with NH-containing aglycones (for example, amines) are called N-glycosides. These include nucleosides, which are important in the chemistry of nucleic acids. Examples of S-glycosides (thioglycosides) are known, for example sinigrin contained in mustard, the hydrolysis of which produces mustard oil (the active ingredient of mustard plasters).



The human body, as well as other living beings, requires energy. Without it, no processes can take place. After all, every biochemical reaction, any enzymatic process or metabolic stage needs an energy source.

Therefore, the importance of substances that provide the body with strength to live is very great and important. What are these substances? Carbohydrates, proteins, each of them is different, they belong to completely different classes chemical compounds, but one of their functions is similar - providing the body necessary energy for life. Let's consider one group of listed substances- carbohydrates.

Classification of carbohydrates

Since their discovery, the composition and structure of carbohydrates have been determined by their name. After all, according to early sources, it was believed that this is a group of compounds whose structure contains carbon atoms associated with water molecules.

A more thorough analysis, as well as accumulated information about the diversity of these substances, made it possible to prove that not all representatives have only this composition. However, this feature is still one of those that determines the structure of carbohydrates.

The modern classification of this group of compounds is as follows:

1. Monosaccharides (ribose, fructose, glucose, etc.).
2. Oligosaccharides (bioses, trioses).
3. Polysaccharides (starch, cellulose).

Also, all carbohydrates can be divided into the following two large groups:

• restorative;
• non-restorative.

Let's look at the structure of carbohydrate molecules of each group in more detail.

Monosaccharides: characteristics

This category includes all simple carbohydrates, which contain an aldehyde (aldose) or ketone (ketose) group and no more than 10 carbon atoms in the chain structure. If you look at the number of atoms in the main chain, then monosaccharides can be divided into:

• trioses (glyceraldehyde);
• tetroses (erythrulose, erythrose);
• pentoses (ribose and deoxyribose);
• hexoses (glucose, fructose).

All other representatives are not as important for the body as those listed.

Features of the structure of molecules

According to their structure, monosaccharides can be presented both in the form of a chain and in the form of a cyclic carbohydrate. How does this happen? The thing is that the central carbon atom in the compound is an asymmetric center around which the molecule in solution is able to rotate. This is how optical isomers of L- and D-form monosaccharides are formed. In this case, the glucose formula, written in the form of a straight chain, can be mentally grabbed by the aldehyde group (or ketone) and rolled into a ball. You will get the corresponding cyclic formula.

Carbohydrates of the monosa series are quite simple: a series of carbon atoms forming a chain or cycle, from each of which hydroxyl groups and hydrogen atoms are located on different or one side. If all structures of the same name are on one side, then a D-isomer is formed, if on different ones, alternating with each other, then an L-isomer is formed. If we write general formula the most common representative of glucose monosaccharides in molecular form, it will have the form: C 6 H 12 O 6. Moreover, this entry reflects the structure of fructose too. After all, chemically these two monoses are structural isomers. Glucose is an aldehyde alcohol, fructose is a keto alcohol.

The structure and properties of carbohydrates of a number of monosaccharides are closely interrelated. Indeed, due to the presence of aldehyde and ketone groups in the structure, they belong to aldehyde and ketone alcohols, which determines them chemical nature and the reactions they are capable of entering into.

Thus, glucose exhibits the following chemical properties:

1. Reactions caused by the presence of a carbonyl group:

• oxidation - “silver mirror” reaction;
• with freshly precipitated (II) - aldonic acid;
• strong oxidizing agents are capable of forming dibasic acids (aldaric acids), transforming not only the aldehyde group, but also one hydroxyl group;
• reduction - converted to polyhydric alcohols.

2. The molecule also contains hydroxyl groups, which reflects the structure. Properties of carbohydrates affected by these groups:

• ability to alkylate - form ethers;
• acylation - formation;
• qualitative reaction to copper(II) hydroxide.

3. Narrowly specific properties of glucose:

• butyric acid;
• alcohol;
• lactic acid fermentation.

Functions performed in the body

The structure and functions of carbohydrates in a number of monosaccharides are closely related. The latter consist, first of all, in participation in the biochemical reactions of living organisms. What role do monosaccharides play in this?

1. Basis for the production of oligo- and polysaccharides.
2. Pentoses (ribose and deoxyribose) are the most important molecules involved in the formation of ATP, RNA, and DNA. And they, in turn, are the main suppliers of hereditary material, energy and protein.
3. The concentration of glucose in human blood is a reliable indicator of osmotic pressure and its changes.

Oligosaccharides: structure

The structure of carbohydrates in this group is reduced to the presence of two (diose) or three (triose) monosaccharide molecules in the composition. There are also those that contain 4, 5 or more structures (up to 10), but the most common are disaccharides. That is, during hydrolysis, such compounds break down to form glucose, fructose, pentose, and so on. What compounds fall into this category? A typical example is (regular cane (the main component of milk), maltose, lactulose, isomaltose.

The chemical structure of carbohydrates of this series has the following features:

1. General molecular formula: C 12 H 22 O 11.
2. Two identical or different monosa residues in the disaccharide structure are connected to each other using a glycosidic bridge. The reducing power of sugar will depend on the nature of this compound.
3. Reducing disaccharides. Structure of carbohydrates of this type consists in the formation of a glycosidic bridge between the hydroxyl of the aldehyde and the hydroxyl group of different monosaccharide molecules. These include: maltose, lactose and so on.
4. Non-reducing - a typical example is sucrose - when a bridge is formed between the hydroxyls of only the corresponding groups, without the participation of the aldehyde structure.

Thus, the structure of carbohydrates can be briefly represented as molecular formula. If a detailed detailed structure is needed, then it can be depicted using Fisher’s graphic projections or Haworth’s formulas. Specifically, two cyclic monomers (monoses) are either different or identical (depending on the oligosaccharide), connected to each other by a glycosidic bridge. When constructing, the restoring power must be taken into account to correctly display the connection.

Examples of disaccharide molecules

If the task is in the form: “Note the structural features of carbohydrates,” then for disaccharides it is best to first indicate which monosaccharide residues it consists of. The most common types are:

• sucrose - built from alpha-glucose and beta-fructose;
• maltose - from glucose residues;
• cellobiose - consists of two D-form beta-glucose residues;
• lactose - galactose + glucose;
• lactulose - galactose + fructose and so on.

Then, based on the available balances, you should compile structural formula with a clear indication of the type of glycosidic bridge.

Significance for living organisms

The role of disaccharides is also very important; not only the structure is important. The functions of carbohydrates and fats are generally similar. It is based on the energy component. However, for some individual disaccharides their special significance should be indicated.

1. Sucrose is the main source of glucose in the human body.
2. Lactose is found in breast milk mammals, including up to 8% in females.
3. Lactulose is obtained in the laboratory for use in medical purposes, and is also added in the production of dairy products.

Any disaccharide, trisaccharide, etc. in the human body and other creatures undergoes instant hydrolysis with the formation of monosaccharides. It is this feature that underlies the use of this class of carbohydrates by humans in raw, unchanged form (beet or cane sugar).

Polysaccharides: features of molecules

Functions, composition and structure of carbohydrates this series are of great importance for living organisms, as well as for economic activity person. First, you need to figure out what carbohydrates are polysaccharides.

There are quite a lot of them:

• starch;
• glycogen;
• murein;
• glucomannan;
• cellulose;
• dextrin;
• galactomannan;
• muromin;
• amylose;
• chitin.

Is not full list, but only the most significant for animals and plants. If you complete the task “Note the structural features of carbohydrates of a number of polysaccharides,” then first of all you should pay attention to their spatial structure. These are very voluminous, gigantic molecules consisting of hundreds of monomer units cross-linked by glycosidic bonds. chemical bonds. Often the structure of carbohydrate molecules of polysaccharides is a layered composition.

There is a certain classification of such molecules.

1. Homopolysaccharides - consist of identical, repeatedly repeating monosaccharide units. Depending on the monoses, they can be hexoses, pentoses, and so on (glucans, mannans, galactans).
2. Heteropolysaccharides are formed by different monomer units.

Compounds with a linear spatial structure include, for example, cellulose. Most polysaccharides have a branched structure - starch, glycogen, chitin, and so on.

Role in living things

The structure and functions of carbohydrates in this group are closely related to the life activity of all creatures. For example, plants accumulate starch in different parts of the shoot or root as a reserve nutrient. The main source of energy for animals is, again, polysaccharides, the breakdown of which produces quite a lot of energy.

Carbohydrates play a very significant role. The cover of many insects and crustaceans consists of chitin, murein is a component cell wall bacteria, cellulose is the basis of plants.

The reserve nutrient of animal origin is glycogen molecules, or, as it is more often called, animal fat. It is stored in certain parts of the body and performs not only energy, but also protective function from mechanical influences.

For most organisms, the structure of carbohydrates is of great importance. The biology of every animal and plant is such that it requires a constant, inexhaustible source of energy. And only they can provide this, and most of all in the form of polysaccharides. Thus, the complete breakdown of 1 g of carbohydrate as a result of metabolic processes leads to the release of 4.1 kcal of energy! This is the maximum, no other connection gives more. That is why carbohydrates must be present in the diet of any person and animal. Plants take care of themselves: during the process of photosynthesis, they form starch within themselves and store it.

General properties of carbohydrates

The structure of fats, proteins and carbohydrates is generally similar. After all, they are all macromolecules. Even some of their functions have general nature. The role and significance of all carbohydrates in the life of the planet’s biomass should be summarized.

1. The composition and structure of carbohydrates imply their use as building material for the shell of plant cells, animal and bacterial membranes, as well as the formation of intracellular organelles.
2. Protective function. It is characteristic of plant organisms and manifests itself in the formation of thorns, thorns, and so on.
3. Plastic role - the formation of vital molecules (DNA, RNA, ATP and others).
4. Receptor function. Polysaccharides and oligosaccharides are active participants in transport transfers through cell membrane, “guardians” that capture impacts.
5. The energy role is the most significant. Provides maximum energy for all intracellular processes, as well as the functioning of the entire organism as a whole.
6. Regulation of osmotic pressure - glucose carries out such control.
7. Some polysaccharides become a reserve nutrient, a source of energy for animal creatures.

Thus, it is obvious that the structure of fats, proteins and carbohydrates, their functions and role in living systems are of decisive and determining importance. These molecules are the creators of life, they also preserve and support it.

Carbohydrates with other high molecular weight compounds

The role of carbohydrates is also known, not in pure form, but in combination with other molecules. These include the most common ones:

• glycosaminoglycans or mucopolysaccharides;
• glycoproteins.

The structure and properties of carbohydrates of this type are quite complex, because a variety of functional groups are combined into a complex. The main role of molecules of this type is participation in many life processes of organisms. Representatives are: hyaluronic acid, chondroitin sulfate, heparan, keratan sulfate and others.

There are also complexes of polysaccharides with other biologically active molecules. For example, glycoproteins or lipopolysaccharides. Their existence is important in the formation of the body’s immunological reactions, since they are part of the cells of the lymphatic system.