Chapter II. LIPIDS
§ 4. CLASSIFICATION AND FUNCTIONS OF LIPIDS
Lipids are a heterogeneous group of chemical compounds that are insoluble in water, but highly soluble in non-polar organic solvents: chloroform, ether, acetone, benzene, etc., i.e. Their common property is hydrophobicity (hydro - water, phobia - fear). Due to the wide variety of lipids, it is impossible to give them a more precise definition. Lipids in most cases are esters of fatty acids and some alcohol. The following classes of lipids are distinguished: triacylglycerols, or fats, phospholipids, glycolipids, steroids, waxes, terpenes. There are two categories of lipids—saponifiable and unsaponifiable. Saponifiers include substances containing an ester bond (waxes, triacylglycerols, phospholipids, etc.). Unsaponifiables include steroids and terpenes.
Triacylglycerols, or fats
Triacylglycerols are esters of the trihydric alcohol glycerol
and fatty (higher carboxylic) acids. The general formula of fatty acids is: R-COOH, where R is a hydrocarbon radical. Natural fatty acids contain from 4 to 24 carbon atoms. As an example, we give the formula of one of the most common stearic acids in fats:
CH 3 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -COOH
IN general view The triacylglycerol molecule can be written as follows:
If triacyoglycerol contains residues of various acids (R 1 R 2 R 3), then the central carbon atom in the glycerol residue becomes chiral.
Triacylglycerols are non-polar and therefore practically insoluble in water. The main function of triacylglycerols is energy storage. When 1 g of fat is oxidized, 39 kJ of energy is released. Triacylglycerols accumulate in adipose tissue, which, in addition to storing fat, performs a thermal insulating function and protects organs from mechanical damage. More detailed information about fats and fatty acids you will find in the next paragraph.
Interesting to know! The fat that fills the camel's hump serves, first of all, not as a source of energy, but as a source of water formed during its oxidation.
Phospholipids
Phospholipids contain hydrophobic and hydrophilic regions and therefore have amphiphilic properties, i.e. they are able to dissolve in non-polar solvents and form stable emulsions with water.
Phospholipids, depending on the presence of glycerol and sphingosine alcohols in their composition, are divided into glycerophospholipids And sphingophospholipids.
Glycerophospholipids
The structure of the glycerophospholipid molecule is based on phosphatidic acid, formed by glycerol, two fatty acids and phosphoric acids:
In glycerophospholipid molecules, an HO-containing polar molecule is attached to phosphatidic acid by an ester bond. The formula of glycerophospholipids can be represented as follows:
where X is the residue of a HO-containing polar molecule (polar group). The names of phospholipids are formed depending on the presence of one or another polar group in their composition. Glycerophospholipids containing an ethanolamine residue as a polar group,
HO-CH 2 -CH 2 -NH 2
are called phosphatidylethanolamines, a choline residue
– phosphatidylcholines, serine
– phosphatidylserines.
The formula for phosphatidylethanolamine looks like this:
Glycerophospholipids differ from each other not only in their polar groups, but also in their fatty acid residues. They contain both saturated (usually consisting of 16–18 carbon atoms) and unsaturated (usually containing 16–18 carbon atoms and 1–4 double bonds) fatty acids.
Sphingophospholipids
Sphingophospholipids are similar in composition to glycerophospholipids, but instead of glycerol they contain the amino alcohol sphingosine:
or dihydrosphingazine:
The most common sphingophospholipids are sphingomyelins. They are formed by sphingosine, choline, fatty acid and phosphoric acid:
The molecules of both glycerophospholipids and sphingophospholipids consist of a polar head (formed by phosphoric acid and a polar group) and two hydrocarbon nonpolar tails (Fig. 1). In glycerophospholipids, both non-polar tails are fatty acid radicals; in sphingophospholipids, one tail is a fatty acid radical, the other is a hydrocarbon chain of the sphingazine alcohol.
Rice. 1. Schematic representation of a phospholipid molecule.
When shaken in water, phospholipids spontaneously form micelles, in which non-polar tails are collected inside the particle, and polar heads are located on its surface, interacting with water molecules (Fig. 2a). Phospholipids are also capable of forming bilayers(Fig. 2b) and liposomes– closed bubbles surrounded by a continuous bilayer (Fig. 2c).
Rice. 2. Structures formed by phospholipids.
The ability of phospholipids to form a bilayer underlies the formation of cell membranes.
Glycolipids
Glycolipids contain a carbohydrate component. These include glycosphingolipids, which contain, in addition to carbohydrate, alcohol, sphingosine and a fatty acid residue:
They, like phospholipids, consist of a polar head and two non-polar tails. Glycolipids are located on the outer layer of the membrane and are integral part receptors ensure cell interaction. There are especially many of them in nervous tissue.
Steroids
Steroids are derivatives cyclopentaneperhydrophenanthrene(Fig. 3). One of the most important representatives of steroids is cholesterol. In the body it is found both in a free state and in a bound state, forming esters with fatty acids (Fig. 3). In its free form, cholesterol is part of blood membranes and lipoproteins. Cholesterol esters are its storage form. Cholesterol is the precursor of all other steroids: sex hormones (testosterone, estradiol, etc.), adrenal hormones (corticosterone, etc.), bile acids (deoxycholic acid, etc.), vitamin D (Fig. 3).
Interesting to know! The adult body contains about 140 g of cholesterol, most of it is found in the nervous tissue and adrenal glands. Every day, 0.3–0.5 g of cholesterol enters the human body, and up to 1 g is synthesized.
Wax
Waxes are esters formed by long-chain fatty acids (carbon number 14–36) and long-chain monohydric alcohols (carbon number 16–22). As an example, consider the formula of a wax formed by oleic alcohol and oleic acid:
Waxes perform a mainly protective function; being on the surface of leaves, stems, fruits, and seeds, they protect tissues from drying out and penetration of microbes. They cover the fur and feathers of animals and birds, protecting them from getting wet. Beeswax serves building material for bees when creating honeycombs. In plankton, wax serves as the main form of energy storage.
Terpenes
Terpene compounds are based on isoprene residues:
Terpenes include essential oils, resin acids, rubber, carotenes, vitamin A, squalene. As an example, here is the formula for squalene:
Squalene is the main component of the secretion of the sebaceous glands.
Lipids are the most important source of the body's energy reserves. The fact is obvious even at the nomenclature level: the Greek “lipos” is translated as fat. Accordingly, the category of lipids unites fat-like substances of biological origin. The functionality of the compounds is quite diverse, which is due to the heterogeneity of the composition of this category of biological objects.
What functions do lipids perform?
List the main functions of lipids in the body, which are basic. At the introductory stage, it is advisable to highlight the key roles of fat-like substances in the cells of the human body. The basic list is the five functions of lipids:
- reserve energy;
- structure-forming;
- transport;
- insulating;
- signal
The secondary tasks that lipids perform in combination with other compounds include regulatory and enzymatic roles.
Energy reserve of the body
This is not only one of the important, but the priority role of fat-like compounds. In fact, part of the lipids is the source of energy for the entire cellular mass. Indeed, fat for cells is an analogue of fuel in a car tank. The energy function of lipids is realized in the following way. Fats and similar substances are oxidized in the mitochondria, breaking down to water and carbon dioxide. The process is accompanied by the release of a significant amount of ATP - high-energy metabolites. Their supply allows the cell to participate in energy-dependent reactions.
Building Blocks
At the same time, lipids perform a construction function: with their help, the cell membrane is formed. The following groups of fat-like substances are involved in the process:
- cholesterol is a lipophilic alcohol;
- glycolipids – compounds of lipids with carbohydrates;
- Phospholipids are esters of complex alcohols and higher carboxylic acids.
It should be noted that the formed membrane does not contain fats directly. The resulting wall between the cell and the external environment turns out to be two-layered. This is achieved due to biphilicity. This characteristic of lipids indicates that one part of the molecule is hydrophobic, that is, insoluble in water, and the second, on the contrary, is hydrophilic. As a result, a cell wall bilayer is formed due to the ordered arrangement of simple lipids. The molecules unfold with hydrophobic regions facing each other, while the hydrophilic tails are directed in and out of the cell.
This determines the protective functions of membrane lipids. First, the membrane gives the cell its shape and even maintains it. Secondly, the double wall is a kind of passport control point that does not allow unwanted visitors to pass through.
Autonomous heating system
Of course, this name is quite arbitrary, but it is quite applicable if we consider what functions lipids perform. The compounds do not so much heat the body as they retain heat inside. A similar role is assigned to fatty deposits that form around various organs and in the subcutaneous tissue. This class of lipids is characterized by high heat-insulating properties, which protects vital organs from hypothermia.
Did you order a taxi?
The transport role of lipids is considered a secondary function. Indeed, the transfer of substances (mainly triglycerides and cholesterol) is carried out by separate structures. These are linked complexes of lipids and proteins called lipoproteins. As is known, fat-like substances are insoluble in water, respectively, in blood plasma. In contrast, the functions of proteins include hydrophilicity. As a result, the lipoprotein core is a collection of triglycerides and cholesterol esters, while the shell is a mixture of protein molecules and free cholesterol. In this form, lipids are delivered to the tissues or back to the liver for removal from the body.
Minor Factors
The list of already listed 5 functions of lipids complements a number of equally important roles:
- enzymatic;
- signal;
- regulatory
Signal function
Some complex lipids, in particular their structure, allow the transmission of nerve impulses between cells. Glycolipids mediate this process. No less important is the ability to recognize intracellular impulses, also realized by fat-like structures. This allows you to select substances needed by the cell from the blood.
Enzymatic function
Lipids, regardless of their location in the membrane or outside it, are not part of enzymes. However, their biosynthesis occurs with the presence of fat-like compounds. Additionally, lipids are involved in protecting the intestinal wall from pancreatic enzymes. The excess of the latter is neutralized by bile, where cholesterol and phospholipids are included in significant quantities.
Composition, properties and functions of lipids in the body
Nutritional value oils and fats used in the baking and confectionery industry.
Cyclic lipids. Role in food technology and vital functions of the body.
Simple and complex lipids.
Composition, properties and functions of lipids in the body.
Lipids in raw materials and food products
Lipids combine a large number of fats and fat-like substances of plant and animal origin, which have a number of common characteristics:
a) insolubility in water (hydrophobicity and good solubility in organic solvents, gasoline, diethyl ether, chloroform, etc.);
b) the presence in their molecules of long-chain hydrocarbon radicals and esters
groupings().
Most lipids are not high molecular weight compounds and consist of several molecules linked to each other. Lipids may contain alcohols and linear chains of a number of carboxylic acids. In some cases, their individual blocks may consist of high molecular weight acids, various phosphoric acid residues, carbohydrates, nitrogenous bases and other components.
Lipids, together with proteins and carbohydrates, make up the bulk of organic substances in all living organisms, being an essential component of every cell.
When lipids are isolated from oilseed raw materials, a large group of accompanying fat-soluble substances passes into the oil: steroids, pigments, fat-soluble vitamins and some other compounds. A mixture of lipids and compounds soluble in them, extracted from natural objects, is called “crude” fat.
Main components of crude fat
Substances accompanying lipids play an important role in food technology and affect the nutritional and physiological value of the resulting food products. Vegetative parts of plants accumulate no more than 5% of lipids, mainly in seeds and fruits. For example, the lipid content in various plant products is (g/100g): sunflower 33-57, cocoa (beans) 49-57, soybeans 14-25, hemp 30-38, wheat 1.9-2.9, peanuts 54- 61, rye 2.1-2.8, flax 27-47, corn 4.8-5.9, coconut 65-72. The lipid content in them depends not only on the individual characteristics of the plants, but also on the variety, location, and growing conditions. Lipids play an important role in the vital processes of the body.
Their functions are very diverse: their role is important in energy processes, in the body’s defense reactions, in its maturation, aging, etc.
Lipids are part of all structural elements cells and primarily cell membranes, influencing their permeability. They participate in the transmission of nerve impulses, provide intercellular contact, active transfer nutrients through membranes, transport of fats in the blood plasma, protein synthesis and various enzymatic processes.
According to their functions in the body, they are conventionally divided into two groups: spare and structural. Spare ones (mainly acylglycerols) have a high calorie content, are the body's energy reserve and are used by it in case of lack of nutrition and diseases.
Storage lipids are storage substances that help the body endure adverse environmental influences. Most plants (up to 90%) contain storage lipids, mainly in the seeds. They are easily extracted from fat-containing material (free lipids).
Structural lipids (primarily phospholipids) form complex complexes with proteins and carbohydrates. They are involved in a variety of complex processes occurring in the cell. By weight, they constitute a significantly smaller group of lipids (3-5% in oil seeds). These are difficult to extract “bound” lipids.
Natural fatty acids that are part of lipids in animals and plants have many common properties. They usually contain a clear number of carbon atoms and have an unbranched chain. Conventionally, fatty acids are divided into three groups: saturated, monounsaturated and polyunsaturated. Unsaturated fatty acids in animals and humans usually contain a double bond between the ninth and tenth carbon atoms; the remaining carboxylic acids that make up fats are as follows:
Most lipids have some common structural features, but a strict classification of lipids does not yet exist. One of the approaches to the classification of lipids is chemical, according to which lipids include derivatives of alcohols and higher fatty acids.
Lipid classification scheme.
Simple lipids. Simple lipids are represented by two-component substances, esters of higher fatty acids with glycerol, higher or polycyclic alcohols.
These include fats and waxes. The most important representatives of simple lipids are acylglycerides (glycerols). They make up the bulk of lipids (95-96%) and are called oils and fats. Fat contains mainly triglycerides, but also contains mono- and diacylglycerols:
The properties of specific oils are determined by the composition of the fatty acids involved in the construction of their molecules and the position occupied by the residues of these acids in the molecules of oils and fats.
Up to 300 carboxylic acids of various structures have been found in fats and oils. However, most of them are present in small quantities.
Stearic and palmitic acids are found in almost all natural oils and fats. Erucic acid is part of rapeseed oil. Most of the most common oils contain unsaturated acids containing 1-3 double bonds. Some acids in natural oils and fats tend to have a cis configuration, i.e. the substituents are distributed on one side of the double bond plane.
Acids with branched carbohydrate chains containing hydroxy, keto and other groups are usually found in small quantities in lipids. The exception is racinolic acid in castor oil. In natural plant triacylglycerols, positions 1 and 3 are preferentially occupied by saturated fatty acid residues, and position 2 is unsaturated. In animal fats the picture is the opposite.
The position of fatty acid residues in triacylglycerols significantly affects their physicochemical properties.
Acylglycerols are liquid or solid substances with low melting points and fairly high boiling points, with high viscosity, colorless and odorless, lighter than water, non-volatile.
Fats are practically insoluble in water, but form emulsions with it.
In addition to the usual physical indicators, fats are characterized by a number of physicochemical constants. These constants for each type of fat and its grade are provided by the standard.
The acid number, or acidity coefficient, shows how many free fatty acids are contained in the fat. It is expressed as the number of mg of KOH required to neutralize free fatty acids in 1 g of fat. The acid number serves as an indicator of the freshness of the fat. On average it fluctuates for different varieties fat from 0.4 to 6.
The saponification number, or saponification coefficient, determines the total amount of acids, both free and bound in triacylglycerols, found in 1 g of fat. Fats containing residues of high molecular weight fatty acids have a lower saponification number than fats formed by low molecular weight acids.
Iodine value is an indicator of fat unsaturation. O is determined by the number of grams of iodine added to 100 g of fat. The higher the iodine value, the more unsaturated the fat is.
Waxes. Waxes are esters of higher fatty acids and high-molecular alcohols (18-30 carbon atoms). The fatty acids that make up waxes are the same as those for fats, but there are also specific ones that are characteristic only of waxes.
For example: carnauba;
cerotinic;
montanova
The general formula of waxes can be written as follows:
Waxes are widespread in nature, covering leaves, stems, and fruits of plants with a thin layer, they protect them from wetting with water, drying out, and the action of microorganisms. The wax content in grains and fruits is low.
Complex lipids. Complex lipids have multicomponent molecules, the individual parts of which are connected by chemical bonds various types. These include phospholipids, consisting of fatty acid residues, glycerol and other polyhydric alcohols, phosphoric acid and nitrogenous bases. In the structure of glycolipids, along with polyhydric alcohols and high-molecular fatty acids, there are also carbohydrates (usually galactose, glucose, mannose residues).
There are also two groups of lipids, which include simple and complex lipids. These are diol lipids, which are simple and complex lipids of dihydric alcohols and high molecular weight fatty acids, in some cases containing phosphoric acid and nitrogenous bases.
Ormitinolipids are built from fatty acid residues, the amino acid ormitine or lysine, and in some cases including dihydric alcohols. The most important and widespread group of complex lipids are phospholipids. Their molecule is built from residues of alcohols, high-molecular fatty acids, phosphoric acid, nitrogenous bases, amino acids and some other compounds.
The general formula of phospholipids (phosphotides) is as follows:
Therefore, the phospholipid molecule has two types of groups: hydrophilic and hydrophobic.
Phosphoric acid residues and nitrogenous bases act as hydrophilic groups, and hydrocarbon radicals act as hydrophobic groups.
Scheme of the structure of phospholipids
Rice. 11. Phospholipid molecule
The hydrophilic polar head is a residue of phosphoric acid and a nitrogenous base.
Hydrophobic tails are hydrocarbon radicals.
Phospholipids are isolated as by-products during the production of oils. They are surfactants that improve the baking properties of wheat flour.
They are also used as emulsifiers in the confectionery industry and in the production of margarine products. They are an essential component of cells.
Together with proteins and carbohydrates, they participate in the construction of cell membranes and subcellular structures that perform the functions of supporting membrane structures. They promote better absorption of fats and prevent fatty liver, playing an important role in the prevention of atherosclerosis.
Lipids, fats and lipoids. Functions of lipids
Lipids (from Greek lipos– fat) include fats and fat-like substances. Contained in almost all cells - from 3 to 15%, and in the cells of subcutaneous fatty tissue up to 50%.
There are especially many lipids in the liver, kidneys, nervous tissue (up to 25%), blood, seeds and fruits of some plants (29-57%). Lipids have different structures, but some properties are common. These organic substances do not dissolve in water, but dissolve well in organic solvents: ether, benzene, gasoline, chloroform, etc. This property is due to the fact that non-polar and hydrophobic structures predominate in lipid molecules. All lipids can be divided into fats and lipoids.
Fats
The most common are fats(neutral fats, triglycerides), which are complex compounds of trihydric alcohol glycerol and high molecular weight fatty acids. The glycerol residue is a substance that is highly soluble in water. Fatty acid residues are hydrocarbon chains that are almost insoluble in water. When a drop of fat enters water, the glycerol part of the molecules is exposed to it, and the chains of fatty acids protrude from the water. Fatty acids contain a carboxyl group (-COOH). It ionizes easily. With its help, fatty acid molecules connect with other molecules.
All fatty acids are divided into two groups - rich And unsaturated . Unsaturated fatty acids do not have double (unsaturated) bonds, saturated ones do. Saturated fatty acids include palmitic, butyric, lauric, stearic, etc. Unsaturated fatty acids include oleic, erucic, linoleic, linolenic, etc. The properties of fats are determined by the qualitative composition of fatty acids and their quantitative ratio.
Fats that contain saturated fatty acids have a high melting point. They are usually hard in consistency. These are fats from many animals, coconut oil. Fats that contain unsaturated fatty acids have a low melting point. These fats are predominantly liquid. Vegetable fats with a liquid consistency break up oils . These fats include fish oil, sunflower, cottonseed, flaxseed, hemp oil, etc.
Lipoids
Lipoids can form complex complexes with proteins, carbohydrates and other substances. The following connections can be distinguished:
- Phospholipids. They are complex compounds of glycerol and fatty acids and contain a phosphoric acid residue. All phospholipid molecules have a polar head and a non-polar tail formed by two fatty acid molecules. Main components of cell membranes.
- Waxes. They are complex lipids, consisting of more complex alcohols than glycerol and fatty acids. Perform a protective function. Animals and plants use them as water-repellent substances that protect against drying out. Waxes cover the surface of plant leaves and the surface of the body of arthropods living on land. Waxes are secreted by the sebaceous glands of mammals and the coccygeal gland of birds. Bees use wax to build honeycombs.
- Steroids (from the Greek stereos - solid). These lipids are characterized by the presence of more complex structures rather than carbohydrates. Steroids include important body substances: vitamin D, hormones of the adrenal cortex, gonads, bile acids, cholesterol.
- Lipoproteins And glycolipids. Lipoproteins consist of proteins and lipids, glucoproteins - of lipids and carbohydrates. There are many glycolipids in the composition of brain tissue and nerve fibers. Lipoproteins are part of many cellular structures and ensure their strength and stability.
Functions of lipids
Fats are the main type stockpiling substances. They are stored in the seed, subcutaneous fatty tissue, adipose tissue, and the fatty body of insects. Fat reserves significantly exceed carbohydrate reserves.
Structural. Lipids are part of the cell membranes of all cells. The ordered arrangement of hydrophilic and hydrophobic ends of molecules has great value for selective membrane permeability.
Energy. Provide 25-30% of all energy needed by the body. When 1 g of fat breaks down, 38.9 kJ of energy is released. This is almost twice as much as carbohydrates and proteins. In migratory birds and hibernating animals, lipids are the only source of energy.
Protective. A layer of fat protects delicate internal organs from shocks, shocks, and damage.
Thermal insulation. Fats do not conduct heat well. Under the skin of some animals (especially marine animals), they are deposited and form layers. For example, a whale has a layer subcutaneous fat about 1 m, which allows it to live in cold water.
Many mammals have a special adipose tissue, which is called brown fat. It has this color because it is rich in red-brown colored mitochondria, as they contain iron-containing proteins. This tissue produces thermal energy, necessary for animals in low conditions
temperatures Brown fat surrounds vital organs (heart, brain, etc.) or lies in the path of the blood that flows to them, and thus directs heat to them.
Endogenous water suppliers
When 100 g of fat is oxidized, 107 ml of water is released. Thanks to this water, many desert animals exist: camels, jerboas, etc. During hibernation, animals also produce endogenous water from fats.
A fatty substance covers the surface of the leaves and prevents them from getting wet during rains.
Some lipids have high biological activity: a number of vitamins (A, D, etc.), some hormones (estradiol, testosterone), prostaglandins.
Structure of lipids, fatty acids
Lipids - a fairly large group of organic compounds present in all living cells that do not dissolve in water, but dissolve well in non-polar organic solvents (gasoline, ether, chloroform, benzene, etc.).
Note 1
Lipids have a wide variety of chemical structures, but true lipids are esters of fatty acids and any alcohol.
U fatty acids the molecules are small and have a long chain, most often consisting of 19 or 18 carbon atoms. The molecule also contains hydrogen atoms and carboxyl group(-COOH). Their hydrocarbon “tails” are hydrophobic, and the carboxyl group is hydrophilic, so esters are easily formed.
Sometimes fatty acids contain one or more double bonds (C–C). In this case, fatty acids, as well as the lipids that contain them, are called unsaturated .
Fatty acids and lipids whose molecules lack double bonds are called saturated . They are formed by the addition of an additional pair of hydrogen atoms at the site of the double bond of an unsaturated acid.
Unsaturated fatty acids melt at lower temperatures than saturated fatty acids.
Example 1
Oleic acid (Mp = 13.4˚C) at room temperature liquid, while palmitic and stearic acids (melt. is 63.1 and 69.9˚C, respectively) under these conditions remain solid.
Definition 1
Most lipids are esters formed by the trihydric alcohol glycerol and three fatty acid residues. These connections are called triglycerides, or triacylglycerols.
Fats and oils
Lipids are divided into fats and oils . It depends on what state they remain in at room temperature: solid (fats) or liquid (oils).
The melting point of lipids is lower, the greater the proportion of unsaturated fatty acids in them.
Oils tend to have more unsaturated fatty acids than fats.
Example 2
The bodies of animals living in cold climate zones (fish of the Arctic seas) usually contain more unsaturated triacylglycerols than those living in southern latitudes. Therefore, their body remains flexible even at low temperatures. environment.
Functions of lipids
Important groups of lipids also include
- steroids (cholesterol, bile acids, vitamin D, sex hormones, etc.),
- terpenes (carotenoids, vitamin K, plant growth substances – gibberellins),
- waxes,
- phospholipids,
- glycolipids,
- lipoproteins.
Note 2
Lipids are an important source of energy.
As a result of oxidation, lipids provide twice as much energy as proteins and carbohydrates, that is, they are an economical form of storing reserve nutrients. This is due to the fact that lipids contain more hydrogen and very little oxygen compared to proteins and carbohydrates.
Example 3
Hibernating animals accumulate fats, and dormant plants accumulate oils. They spend them later in the process of life. Due to their high lipid content, plant seeds provide energy for the development of the embryo and sprout until it begins to feed itself. The seeds of many plants (sunflower, soybean, flax, corn, mustard, coconut palm, castor oil, etc.) are raw materials for producing oils industrially.
Due to their insolubility in water, lipids are important structural component cell membranes consisting mainly of phospholipids. In addition, they contain glycolipids and lipoproteins.