lipids and monosaccharides. General biology: Carbohydrates and lipids. The biological role of carbohydrates

Lipids. Carbohydrates.

In addition to inorganic substances and their ions, all cellular structures also consist of organic compounds - proteins, lipids, carbohydrates and nucleic acids.

carbohydrates and lipids.

Carbohydrates (sugars) -bio organic compounds carbon and water, which are part of all living organisms: The general formula is Cn (H2O) n.

Water-soluble carbohydrates.

Monosaccharides:

glucose is the main source of energy for cellular respiration;

fructose - an integral part of the nectar of flowers and fruit juices;

ribose and deoxyribose are structural elements of nucleotides, which are monomers of RNA and DNA;

disaccharides :

sucrose (glucose + fructose) - the main product of photosynthesis transported in plants;

lactose (glucose-N-galactose) - is part of the milk of mammals;

maltose (glucose + glucose) is a source of energy in germinating seeds.

Functions of soluble carbohydrates: transport, protective, signal, energy.

Water insoluble carbohydrates:

Starch is a mixture of two polymers: amylose and amylopectin. A branched spiralized molecule that serves as a reserve substance in plant tissues;

Cellulose (cellulose) is a polymer consisting of several straight parallel chains connected by hydrogen bonds. This structure prevents the penetration of water and ensures the stability of the cellulose casings. plant cells;

Chitin is the main structural element of the integument of arthropods and the cell walls of fungi;

Glycogen is the reserve substance of an animal cell. The monomer is a-glucose.

Functions of insoluble carbohydrates: structural, storage, energy, protective.

Lipids- organic compounds, most of which are esters of glycerol and fatty acids.

Insoluble in water, but soluble in non-polar solvents. Present in all cells. Lipids are made up of hydrogen, oxygen and carbon atoms.

Types of lipids: fats, waxes, phospholipids, steroids.

Functions of lipids :

Storage - fats are deposited in the reserve in the tissues of vertebrates;

Energy - half of the energy consumed by the cells of vertebrates at rest is formed as a result of fat oxidation. Fats are also used as a source of water

Protective - the subcutaneous fat layer protects the body from mechanical damage;

Structural - phospholipids are part of cell membranes;

Thermal insulation - subcutaneous fat helps to keep warm;

Electrical insulating - myelin, secreted by Schwann cells, isolates some neurons, which many times accelerates the transmission of nerve impulses;

Nutrient - bile acids and vitamin D are formed from steroids;

Lubricating - waxes cover the skin, wool, feathers and protect them from water. The leaves of many plants are covered with a wax coating; wax is used in the construction of honeycombs;

Hormonal - adrenal hormone - cortisone - and sex hormones are lipid in nature. Their molecules do not contain fatty acids.

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

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

Ribose and deoxyribose belong to the group of pentoses, are part of the RNA and DNA nucleotides, ribonucleoside triphosphates and deoxyribonucleoside triphosphates, etc. Deoxyribose (C 5 H 10 O 4) differs from ribose (C 5 H 10 O 5) in that at the second carbon atom it has a hydrogen 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 lies in the fact that at the first carbon atom in α-glucose the hydroxyl group is located under the plane of the ring, while in β-glucose it is above the plane.

Glucose is:

one of the most common monosaccharides,

the most important source of energy for all types of work occurring in the cell (this energy is released during the oxidation of glucose during respiration),

monomer of many oligosaccharides and polysaccharides,

an essential component of blood.

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

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

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

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

Lactose or milk sugar, is a disaccharide consisting of glucose and galactose residues. 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 a multitude (several tens or more) of monosaccharide molecules. Properties of polysaccharides- do not dissolve or dissolve poorly in water, do not form clearly formed crystals, do not have a sweet taste.

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

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

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

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

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

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

Functions of carbohydrates

Function	Examples and explanations
Energy	The main source of energy for all kinds of work occurring in cells. When splitting 1 g of carbohydrates, 17.6 kJ are released.
Structural	Cellulose is the cell wall of plants, murein is the cell wall of bacteria, chitin is the cell wall of fungi and the integuments of arthropods.
Reserve	The reserve carbohydrate in animals and fungi is glycogen, in plants - starch, inulin.
Protective	Mucus protects the intestines, bronchi from mechanical damage. Heparin prevents blood clotting in animals and humans.

See here an animation about the classification and biological functions of carbohydrates

The structure and function of lipids

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

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

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

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

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

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

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

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

Glycolipids- see above.

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

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

See here an animation about the classification and biological functions of lipids

Functions of lipids

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

As you know, the most important groups of organic substances that determine the basic properties of a cell, an organism are proteins, carbohydrates, fats, nucleic acids, individual nucleotides (in particular, ATP). Each of these groups performs its function (functions) in the process of life of the organism.

CARBOHYDRATES (monosaccharides, polysaccharides) - organic substances whose molecules include hydrogen and oxygen. In this case, the ratio of these elements is similar to their ratio in a water molecule, i.e. There is one oxygen atom for every 2 hydrogen atoms.

Monosaccharides include ribose, deoxyribose, glucose, fructose, galactose.

First-order polysaccharides include sucrose, lactose, and maltose.

Second order polysaccharides: starch, glycogen, fiber.

Carbohydrates perform the following functions in the body:

energy,

Structural (because they are part of cell membranes and subcellular formations),

supply of nutrients,

Protective (viscous secrets that protect the walls of hollow organs from mechanical, chemical damage, the penetration of harmful bacteria and viruses are rich in carbohydrates).

LIPIDS. This term includes fats and fat-like substances. These are organic compounds with different structures, but common properties. They are insoluble in water, but readily soluble in organic solvents.

The main functions of lipids:

Structural (lipids take part in the construction of cell membranes of all organs and tissues),

Energy function (providing 25-50% of the body's energy),

The supply of nutrients (“energy canned food”),

Thermoregulation.

PROTEINS. Proteins are irregular polymers whose monomers are amino acids. Most proteins contain 20 amino acids. Each of them contains the same groups of atoms: the amino group - NH2 and the carboxyl group - COOH. Molecules that lie outside the amino and carboxyl groups are called radicals (R). The cell contains free amino acids that make up the amino acid pool, due to which new proteins are synthesized. This fund is constantly replenished due to the breakdown of food proteins by digestive enzymes or their own storage proteins.

The connection of amino acids occurs through groups common to them: the amino group of one amino acid is connected to the carboxyl group of another amino acid, and when they are combined, a water molecule is released. Between the connected amino acids there is a bond called a peptide.

The resulting compound of several amino acids is called a peptide, and the compound of a large number of amino acids is called a polypeptide. Thus, a protein may be one or more polypeptides.

Levels of organization of a protein molecule. The primary, simplest structure is the polypeptide chain, i.e. a string of amino acids linked by peptide bonds. In the primary structure, all bonds between amino acids are covalent, and therefore strong.

The secondary structure corresponds to the twisting of the protein thread in the form of a spiral. Between groups -C=O, located on the same turn of the helix, and groups -N-H on the other turn, hydrogen bonds are formed, which are weaker than covalent ones, but provide sufficient strength of the secondary structure.

Quaternary structure. Due to the combination of several protein molecules with each other, a quaternary structure is formed. If the peptide filaments are stacked in the form of a coil, such proteins are called globular, if in the form of bundles of filaments - fibrillar.

Protein functions. The variety of functions that proteins perform in a living organism is so great that it is advisable to present it in the form of the following scheme (Fig. 1).

Fig.1.

It should be noted that in addition to those presented in the diagram, proteins also perform an energy function. However, proteins are used as energy sources only when the main sources of carbohydrates and fats are depleted.

NUCLEIC ACIDS. Nucleic acids are natural macromolecular compounds that provide storage and transmission hereditary information. Described for the first time in 1869 by the Swiss biochemist F. Misher.

In nature, there are two types of nucleic acids, differing in composition, structure and function. One contains the carbohydrate component ribose (RNA), the other contains deoxyribose (DNA).

Nucleic acids are the most important biopolymers that determine the basic properties of living things. So DNA is a polymer molecule consisting of hundreds of thousands of monomers - deoxyribonucleotides.

DNA. Nucleotide composition of DNA: DNA contains 4 bases:

adenine (A)

guanine (G)

cytosine (C).

The amount of adenine is always equal to the amount of thymine (A=T), and the amount of guanine is always equal to the amount of cytosine (Chargaff's rule). This testified to some strict regularities in the structure of DNA. In the early 50s of the last century, the structure of DNA was elucidated - a double helix, with a sugar-phosphate backbone on the periphery of the molecule, and purine (adenine and guanine) and pyrimidine (cytosine and thymine) bases in the middle. Each of the base pairs has a symmetry that allows it to be included in a double helix in two orientations: (A=T and T=A) and (C=G and G=C). In each of the DNA chains, the bases can alternate in all existing ways.

If the sequence of bases in one chain is known (for example, T-C-G-C-A-T), then, due to the specificity of pairing (complementarity), the sequence of its "partner" chain becomes known: A-G-C-G-T -BUT.

RNA. The RNA molecule is also a polymer, the monomer of which is a ribonucleotide. RNA is a single-stranded molecule and is built in the same way as one of the DNA chains. RNA nucleotides are very close to DNA nucleotides but are not completely identical: instead of thymine (T), RNA has a pyrimidine, uracil, close to it in structure.

According to the functions performed, RNAs are divided into the following types:

Transfer RNA (t-RNA) is the shortest, 80-100 nucleotides; t-RNA accounts for about 10% of the total cell RNA content. Its function is to carry amino acids into ribosomes, to the site of protein synthesis.

Ribosomal RNA (r-RNA) is the largest, 3-5 thousand nucleotides (about 90% of the cell's RNA content).

Messenger RNA (i-RNA), they account for about 0.5-1% of the total RNA content in the cell. Its function is to transfer information about the protein structure from DNA to the site of protein synthesis in ribosomes.

Rice. 2.

All types of RNA are synthesized on DNA, which serves as a kind of matrix.

The mass fraction of carbohydrates in wildlife is greater than other organic compounds. In the cells of animals and fungi, carbohydrates are contained in a small amount (about 1% of dry weight, in the cells of the liver and muscles - up to 5%), while in plant cells their content is much higher (60 - 90%). Carbohydrates are formed mainly as a result of photosynthesis. Heterotrophic organisms obtain carbohydrates from food or synthesize them from other organic compounds (fats, amino acids, etc.).

Carbohydrates are organic compounds in which the ratio of carbon, oxygen basically corresponds to the formula (CH 2 O) n, where n \u003d 3 and more. However, there are carbohydrates in which this ratio is somewhat different, and some contain nitrogen, phosphorus or sulfur atoms.

Carbohydrates include monosaccharides, oligosaccharides and polysaccharides.

Monosaccharides - highly soluble in substances, have a sweet taste. Consider the structure of monosaccharides using glucose as an example. Its molecular formula is C 6 H 12 0 6 .

Glucose molecule

Monosaccharides are classified according to the number of carbon atoms in their molecules. The most important for wildlife are pentoses (compounds with five carbon atoms) and hexoses (compounds with six carbon atoms). Common hexoses, in addition to glucose, are fructose and galactose. Of the pentoses, ribose and deoxyribose are common, the residues of which are part of the nucleic acid monomers. Monosaccharides are able to combine with each other using -OH groups. In this case, it is formed between two monosaccharide residues through an oxygen atom (-O-).

Scheme of the formation of polysaccharides on the example of cellulose (a fragment of a molecule)

Oligosaccharides and polysaccharides are composed of monosaccharide residues. Oligosaccharides are polymeric carbohydrates in which from 2 to 10 monosaccharide units are connected covalent bonds. For example, disaccharides are formed by two monosaccharide residues. In nature, such disaccharides are common: common food sugar - sucrose (consists of glucose and fructose residues) and milk sugar - lactose (consists of glucose and galactose residues).

As a result of the interaction of monosaccharides, chains of hundreds and thousands of residues can be formed - polysaccharides. These compounds are poorly soluble in water and do not have a sweet taste. In nature, polysaccharides formed from glucose residues are common, these are cellulose, glycogen and starch. Another common polysaccharide in nature, chitin, consists of nitrogen-containing derivatives of glucose.

The functions of carbohydrates are quite diverse. The energy function is due to the fact that as a result of the complete breakdown of 1 g of carbohydrates, 17.6 kJ of energy is released. Part of this energy ensures the functioning of the body, and part is released in the form of heat. The greatest amount of energy is released as a result of the oxidation of carbohydrates with oxygen, however, the breakdown of carbohydrates with the release of energy can occur in other cases. This is important for organisms that exist in conditions of lack or absence of oxygen.

Polysaccharides can accumulate in cells, that is, they can perform a reserve function. Glycogen accumulates in animal and fungal cells, and starch accumulates in plant cells. The construction (structural) function of carbohydrates is that polysaccharides are part of certain structures. So, chitin forms the external skeleton of arthropods and is contained in the cell wall of fungi, and cellulose is found in the cell wall of plants. Carbohydrates associated with and lipids are located outside the plasma membrane of the animal cell and the cell wall of bacteria. Special compounds of carbohydrates with proteins (mucopolysaccharides) perform the function of lubrication in the organisms of vertebrates and humans - they are part of the liquid, lubricates the surfaces of the joints.

Polysaccharide chains can be linear in space or branch, which is associated with their functions. The chains of polysaccharides, which are part of the structures of a cell or organism, are connected by numerous bonds to each other, which ensures the strength and chemical resistance of these substances. However, most polysaccharides are the reserve substances of animal and plant cells, have numerous branched chains, as a result of which these molecules are quickly broken down into glucose in the cell at many points simultaneously.

Structure, properties and biological role of lipids

Every cell in the body contains lipids. Lipids are derivatives of fatty acids and polyhydric alcohols or aldehydes. Fatty acids are organic acids with a chain of four or more (up to 24) carbon atoms, usually a straight chain. Some lipids have a slightly different structure, but are also poorly soluble in water.

Lipids are hydrophobic, but dissolve well in non-polar solvents: benzene, chloroform, acetone.

A large group of lipids are fats. Fats are esters of the trihydric alcohol glycerol and three unbranched fatty acid residues. One of the most important functions of fats is energy. In the case of complete breakdown of 1 g of fat, 38.9 kJ of energy is released - twice as much as for the complete breakdown of a similar amount of carbohydrates or proteins. The reserve function is that fats are contained in the cytoplasm of cells in the form of inclusions - in adipose cells, sunflower seeds, etc. Fat reserves can be used by organisms as reserve nutrients and as a source of metabolic water (when 1 g of fat is oxidized, about ml of water).

Accumulating in the subcutaneous adipose tissue of animals, fats protect the body from the effects of sudden changes in temperature, performing a heat-insulating function. This function of fats is due to their low thermal conductivity. Fat reserves in the body can also perform a protective function. In particular, they protect internal organs from mechanical damage.

Compounds similar to fats in structure are waxes, the layer of which covers the leaves and fruits of terrestrial plants, the surface of the chitinous skeleton of many arthropods, preventing excessive evaporation of water from the surface of the body.

Steroids form a separate group of lipids. The most important steroid of the animal organism is cholesterol, a component of cell membranes, as well as a precursor for the synthesis of vitamin D, adrenal and gonadal hormones.

Among lipids, there are compounds formed as a result of the interaction of simple lipid molecules with other substances. These include lipoproteins (compounds of lipids and proteins), glycolipids (lipids and carbohydrates), phospholipids (containing orthophosphoric acid residues)

1. Characteristics of carbohydrates Carbohydrates, or saccharides, organic substances, which include carbon, oxygen, hydrogen. Carbohydrates make up about 1% of the mass of dry matter in animal cells, and up to 5% in liver and muscle cells. Plant cells are the richest in carbohydrates (up to 90% of dry mass). Chemical composition carbohydrates is characterized by their general formula C m (H 2 O) n, where mn. The number of hydrogen atoms in carbohydrate molecules is usually twice the number of oxygen atoms (that is, as in a water molecule). Hence the name carbohydrates.

Simple Carbohydrates Simple carbohydrates are called monosaccharides. Depending on the number of carbon atoms in a monosaccharide molecule, there are: trioses (3C), tetroses (4C), pentoses (5C), hexoses (6C), heptoses (7C). Complex carbohydrates Complex carbohydrates are carbohydrates whose molecules break down during hydrolysis to form simple carbohydrates. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. There are two groups of carbohydrates: simple sugars and complex sugars formed by residues of simple sugars. Simple carbohydrates are called monosaccharides. The general formula of simple sugars (CH 2 O) n, where n 3 1. Characteristics of carbohydrates

Properties of monosaccharides: low molecular weight; sweet taste; easily soluble in water; crystallize; are reducing (restoring) sugars. The most important monosaccharides: Ribose and deoxyribose pentoses, which are part of DNA, RNA. Deoxyribose (C 5 H 10 O 4) differs from ribose (C 5 H 10 O 5) in that it has a hydrogen atom at the second carbon atom, and not a hydroxyl group like that of ribose. 1. Characterization of carbohydrates

The most common hexoses are glucose, fructose and galactose ( general formula C 6 H 12 O 6). Glucose (grape sugar). It is found free in both plants and animals. Glucose is the primary source of energy for cells. Fructose. Widely distributed in nature. It is found in free form in fruits. Especially a lot of it in honey, fruits. Significantly sweeter than glucose and other sugars. Included in the composition of oligo- and polysaccharides, is involved in maintaining the turgor of plant cells. Since fructose metabolism is not regulated by insulin, it is important in the nutrition of diabetic patients. Monosaccharides can be presented in the form of - and -isomers. The hydroxyl group at the first carbon atom can be located both under the ring plane (-isomer) and above it (-isomer). 1. Characterization of carbohydrates

N. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. Oligosaccharides. Oligos" title="(!LANG: Complex carbohydrates are called carbohydrates, the molecules of which decompose during hydrolysis to form simple carbohydrates. Their composition is expressed by the general formula C m (H 2 O) n, where m> n. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. Oligosaccharides Oligos" class="link_thumb"> 6 !} Complex carbohydrates are called carbohydrates, the molecules of which, during hydrolysis, break down to form simple carbohydrates. Their composition is expressed by the general formula C m (H 2 O) n, where m>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 the oligosaccharide molecules, disaccharides, trisaccharides, tetrasaccharides, etc. are distinguished. Disaccharides are the most widely distributed in nature. Oligosaccharides have good solubility in water, they crystallize easily, have, as a rule, a sweet taste, and can be both reducing and non-reducing. 1. Characterization of carbohydrates n. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. Oligosaccharides. Oligos "> n. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. Oligosaccharides. Oligosaccharides are called complex carbohydrates containing from 2 to 10 monosaccharide residues. Depending on the number of monosaccharide residues included in the oligosaccharide molecules, disaccharides, trisaccharides, tetrasaccharides, etc. are distinguished Disaccharides are the most widely distributed in nature.Oligosaccharides have good solubility in water, they crystallize easily, have, as a rule, a sweet taste, and can be both reducing and non-reducing. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. Oligosaccharides. Oligos" title="(!LANG: Complex carbohydrates are called carbohydrates, the molecules of which decompose during hydrolysis to form simple carbohydrates. Their composition is expressed by the general formula C m (H 2 O) n, where m> n. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. Oligosaccharides Oligos"> title="Complex carbohydrates are called carbohydrates, the molecules of which, during hydrolysis, break down to form simple carbohydrates. Their composition is expressed by the general formula C m (H 2 O) n, where m>n. Among complex carbohydrates, oligosaccharides and polysaccharides are distinguished. Oligosaccharides. Oligos"> !}

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

Polysaccharides (Greek poly - many) are polymers and consist of an indefinitely large (up to several hundred or thousands) number of residues of monosaccharide molecules connected by covalent bonds. These include: o starch (reserve carbohydrate of plants); o glycogen (reserve carbohydrate of animals); o cellulose (plant cell wall); o chitin (cell wall of fungi); o murein (cell wall of bacteria). 1. Characterization of carbohydrates

Starch and glycogen molecules consist of α-glucose residues, and cellulose consists of α-glucose residues. In addition, the chains of cellulose do not branch, while those of glycogen branch more strongly than those of starch. With an increase in the amount of monomers, the solubility of polysaccharides decreases and the sweet taste disappears. 1. Characterization of carbohydrates

The main function of carbohydrates is energy. During their enzymatic breakdown and oxidation of carbohydrate molecules, energy is released, which ensures the vital activity of the body. With the complete breakdown of 1 g of carbohydrates, 17.6 kJ are released. 1. Characterization of carbohydrates

Carbohydrates perform a storage function. In excess, they accumulate in the cell as storage substances (starch in plant cells, glycogen in animal cells) and, if necessary, are used by the body as an energy source. Enhanced breakdown of carbohydrates occurs, for example, during seed germination, intense muscular work, and prolonged fasting. 1. Characterization of carbohydrates

The structural or building function of carbohydrates is very important. They are used as a building material. Thus, cellulose, due to its special structure, is insoluble in water and has high strength. On average, 20-40% of plant cell wall material is cellulose, and cotton fibers are almost pure cellulose, which is why they are used to make fabrics. 1. Characterization of carbohydrates

What elements are in carbohydrates? What is the general formula for carbohydrates? Carbon, hydrogen and oxygen. C x (H 2 O) y, where x y. What are the classes of carbohydrates? There are three main classes of carbohydrates: simple - monosaccharides, and complex - oligosaccharides and polysaccharides. Name the most important monosaccharides: From monosaccharides highest value for living organisms have ribose, deoxyribose, glucose, fructose, galactose. Name the most important disaccharides: sucrose (cane sugar), maltose (malt sugar), lactose (milk sugar). Name the most important polysaccharides: starch (plant carbohydrate storage), glycogen (animal storage carbohydrate), cellulose (plant cell wall), chitin (fungal cell wall), murein (bacterial cell wall). What is the difference between alpha and beta glucose isomers? The hydroxyl group at the first carbon atom can be located both under the ring plane (-isomer) and above it (-isomer). Let's summarize:

What is known about the energy function of carbohydrates? This is the main function, with complete oxidation of 1 g, 17.6 kJ is released. Energy. In what form do plants and animals store carbohydrates? Plants are in the form of starch, animals are in the form of glycogen. What is known about the structural function of carbohydrates? The cell wall of plants consists of cellulose, fungi - of chitin, bacteria - of murein. Let's summarize:

Lipids (from the Greek. lipos - fat) - an extensive group of fats and fat-like substances that are found in all living cells. Most of them are non-polar and therefore hydrophobic. They are practically insoluble in water, but highly soluble in organic solvents (gasoline, chloroform, ether, etc.). In some cells, there are very few lipids, only a few percent, but in the cells of the subcutaneous adipose tissue of mammals, their content reaches 90%. By chemical structure lipids are very diverse. 2. Characterization of lipids

1. Simple lipids - fats and waxes. Fats are the simplest and most abundant lipids. Their molecules are formed as a result of the addition of three residues of high molecular weight fatty acids to one molecule of the trihydric alcohol glycerol. Among the compounds of this group, fats are distinguished, which remain solid at a temperature of 20 ° C, and oils, which become liquid under these conditions. Oils are more typical of plants, but can also be found in animals. Fatty acids are a carboxyl group and a hydrocarbon tail, which differs in different fatty acids in the number of -CH 2 groups. The “tail” is non-polar, therefore hydrophobic. Most of the fatty acids are found in the "tail" even number carbon atoms, from 14 to Characterization of lipids

In addition, the hydrocarbon tail may contain varying amounts of double bonds. According to the presence or absence of double bonds in the hydrocarbon tail, they are distinguished: saturated fatty acids and unsaturated fatty acids having double bonds between carbon atoms (-CH=CH-). 2. Characterization of lipids

When a triglyceride molecule is formed, each of the three hydroxyl (-OH) groups of glycerol enters into a condensation reaction with a fatty acid. During the reaction, three ester bonds are formed, so the resulting compound is called an ester. Usually, all three hydroxyl groups of glycerol enter into the reaction, so the reaction product is called triglyceride. Physical properties depend on the composition of their molecules. If saturated fatty acids predominate in triglycerides, then they are solid (fats), if unsaturated liquid (oils). The density of fats is lower than that of water, so they float in water and are on the surface. 2. Characterization of lipids

2. Complex lipids - phospholipids, glycolipids and lipoproteins. Phospholipids are similar in structure to fats, but in their molecule one or two fatty acid residues are replaced by a phosphoric acid residue. Phospholipids are an integral component of cell membranes. Lipids can form complex compounds with substances of other classes, for example, with proteins - lipoproteins and with carbohydrates - glycolipids. 2. Characterization of lipids

3. Steroids are lipids that do not contain fatty acids and have a special structure. Steroids include hormones, in particular cortisone produced by the adrenal cortex, various sex hormones, vitamins A, D, E, K, and plant growth substances. The steroid cholesterol is an important component of cell membranes. 2. Characterization of lipids

Fats are the main storage substance in animals, as well as in some plants. They can also be used as a source of water (when 1 kg of fat is oxidized, 1 kg 100 g of water is formed). This is especially valuable for desert animals that live in conditions of water scarcity. In addition to the water found in food, they use metabolic water. 2. Characterization of lipids

One of the main functions is energy. With the complete oxidation of 1 g of fat, 38.9 kJ of energy is released. That is, fats provide more than 2 times more energy compared to carbohydrates. In vertebrates, approximately half of the energy consumed by cells at rest comes from fat oxidation. 2. Characterization of lipids

Due to their low thermal conductivity, lipids perform a protective function, that is, they serve to insulate organisms. For example, many vertebrates have a well-defined subcutaneous fat layer, which allows them to live in cold climates, while in cetaceans it also plays another role - it contributes to buoyancy. Wax coating on various parts of plants prevents excessive evaporation of water, in animals it plays the role of a water-repellent coating. 2. Characterization of lipids

Lipids also perform a building function, since their insolubility in water makes them the most important components of cell membranes (phospholipids, lipoproteins, glycolipids, cholesterol). Many lipid derivatives (for example, hormones of the adrenal cortex, gonads, vitamins A, D, E, K) are involved in metabolic processes in the body. Therefore, these substances also have a regulatory function. 2. Characterization of lipids

What organic molecules can be called lipids? Substances whose molecules are non-polar and therefore hydrophobic. They are practically insoluble in water, but highly soluble in organic solvents (gasoline, chloroform, ether). What can be said about the structure of fats? Fats are made up of three fatty acid residues attached to one molecule of the trihydric alcohol glycerol. What can be said about phospholipids? Phospholipids are similar in structure to fats, but in their molecule one or two fatty acid residues are replaced by a phosphoric acid residue. Phospholipids are an integral component of cell membranes. What can be said about steroids? Steroids are lipids that do not contain fatty acids and have a special structure. Steroids include hormones, in particular cortisone produced by the adrenal cortex, various sex hormones, vitamins A, D, E, K, and plant growth substances. Let's summarize:

Why are fats the main storage substance in living organisms? With the complete oxidation of 1 g of fat, 38.9 kJ of energy is released. That is, fats provide more than 2 times more energy compared to carbohydrates. A kangaroo rat doesn't drink all his life. How does she do it? Uses metabolic water. When 1 g of fat is oxidized, more than 1 g of water is formed. In addition, water is in food. What hormones are lipids? Cortisone produced by the adrenal cortex, various sex hormones. What lipids perform a building function? Components of cell membranes: phospholipids, lipoproteins, glycolipids, cholesterol. Let's summarize: