A group of organic substances, including fats and fat-like substances (lipoids), are called lipids. Fats are found in all living cells, act as a natural barrier, limiting cell permeability, and are part of hormones.

Structure

Lipids, by chemical nature, are one of three types of vital organic substances. They are practically insoluble in water, i.e. are hydrophobic compounds, but form an emulsion with H2O. Lipids disintegrate in organic solvents - benzene, acetone, alcohols, etc. According to their physical properties, fats are colorless, tasteless and odorless.

Structurally, lipids are compounds of fatty acids and alcohols. When additional groups (phosphorus, sulfur, nitrogen) are added, complex fats are formed. A fat molecule necessarily includes carbon, oxygen and hydrogen atoms.

Fatty acids are aliphatic, i.e. Carboxylic (COOH group) acids that do not contain cyclic carbon bonds. They differ in the amount of -CH2- group.
Acids are released:

• unsaturated - include one or more double bonds (-CH=CH-);
• rich - do not contain double bonds between carbon atoms

Rice. 1. Structure of fatty acids.

They are stored in cells in the form of inclusions - droplets, granules, in a multicellular organism - in the form of adipose tissue consisting of adipocytes - cells capable of storing fats.

Classification

Lipids are complex compounds that occur in various modifications and perform various functions. Therefore, the classification of lipids is extensive and is not limited to one characteristic. The most complete classification by structure is given in the table.

The lipids described above are saponifiable fats - their hydrolysis produces soap. Separately in the group of unsaponifiable fats, i.e. do not interact with water, they release steroids.
They are divided into subgroups depending on their structure:

• sterols - steroid alcohols that are part of animal and plant tissues (cholesterol, ergosterol);
• bile acids - derivatives of cholic acid containing one group -COOH, promote the dissolution of cholesterol and the digestion of lipids (cholic, deoxycholic, lithocholic acids);
• steroid hormones - promote the growth and development of the body (cortisol, testosterone, calcitriol).

Rice. 2. Lipid classification scheme.

Lipoproteins are isolated separately. These are complex complexes of fats and proteins (apolipoproteins). Lipoproteins are classified as complex proteins, not fats. They contain a variety of complex fats - cholesterol, phospholipids, neutral fats, fatty acids.
There are two groups:

• soluble - are part of blood plasma, milk, yolk;
• insoluble - are part of the plasmalemma, nerve fiber sheaths, chloroplasts.

Rice. 3. Lipoproteins.

The most studied lipoproteins are blood plasma. They vary in density. The more fat, the less density.

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Lipids are classified according to their physical structure into solid fats and oils. Based on their presence in the body, they are divided into reserve (unstable, dependent on nutrition) and structural (genetically determined) fats. Fats can be vegetable or animal in origin.

Meaning

Lipids must enter the body with food and participate in metabolism. Depending on the type fats perform in the body various functions:

• triglycerides retain body heat;
• subcutaneous fat protects internal organs;
• phospholipids are part of the membranes of any cell;
• adipose tissue is an energy reserve - the breakdown of 1 g of fat provides 39 kJ of energy;
• glycolipids and a number of other fats perform a receptor function - they bind cells, receiving and transmitting signals received from the external environment;
• phospholipids are involved in blood clotting;
• waxes cover the leaves of plants, at the same time protecting them from drying out and getting wet.

Excess or lack of fat in the body leads to changes in metabolism and disruption of the functions of the body as a whole.

What have we learned?

Fats have a complex structure, are classified according to different characteristics and perform various functions in the body. Lipids consist of fatty acids and alcohols. When additional groups are added, complex fats are formed. Proteins and fats can form complex complexes - lipoproteins. Fats are part of the plasmalemma, blood, tissue of plants and animals, and perform heat-insulating and energy functions.

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In the popular consciousness, lipids are usually understood as fats, but in reality these words are not synonymous, and they should not be confused. Let's try to figure out what it really is and what are the functions of lipids in our body.

general characteristics

The etymology of the word is related to the Greek "lipos", which means fat, hence some confusion. If you follow the generally accepted terminology, then lipids are related to fats as general and specific. This means that all lipids are fats, but not all fats are lipids. It is also important to understand that lipids are organic compounds, while the same oil can be inorganic.

Important! Organic fats and oils are lipids, but the first term is usually applied to substances in a solid state of aggregation, and the second to liquids.

These substances may have different structures, but they always contain alcohol and organic acids, for example, triglycerides, that is, fats as such are formed by combining glycerol (the simplest trihydric alcohol) and carboxylic acids. All the compounds under consideration are characterized by one property - hydrophobicity (“hydro” - water, “phobia” - fear, fear). This term, of course, does not mean physical fear of water. It is applied to substances whose molecules seem to be trying to “stay away from water.” When such contact does occur, the substance seems to push the liquid away from itself, as a result of which the latter is not distributed over its surface, but collects on it in separate drops, “satisfied” with the minimal area “allocated” to it. It is clear that hydrophobic compounds do not dissolve or dissolve very poorly in water, which, however, does not prevent them from dissolving well in other substances (for example, in alcohol). This is the second feature of lipids, which determines their separation into a separate group. The compounds in question are present in all living organisms, and they are present in all tissues and cells.
There are a huge variety of different lipids. For convenience, they are usually divided into simple and complex. The first, in turn, includes fats, fatty acids, fatty aldehydes and fatty alcohols, wax and some other substances, the second - -, glyco-, phosphoglyco-, sphingo-, arsenic lipids, acylglycerides, ceramides, steroids, etc. which compounds are classified as simple and which are complex is determined by their chemical composition, namely whether this molecule contains only oxygen, hydrogen or carbon, or whether other elements are also present.

Did you know? The liver of a healthy person consists of 7-14% lipids. However, in pathological cases with serious diseases of this organ, the amount of fat in it can reach almost half.

Some of these substances are contained in strictly defined cells (in certain organs), while others are present everywhere. The main “place of residence” of these compounds in our body is, of course, adipose tissue, but there are also many of them in nerve cells. Transportation of lipids synthesized by the body or obtained from food products throughout all organs and tissues occurs through blood plasma, where these substances are contained together with proteins.

Main functions

You may not be able to list all the functions of lipids, but it is obvious to everyone that our bodies need fats to function properly. Moreover, we are talking not only about the functioning of the body as a single system, but also about the “health” of each specific cell as its individual “building block”. As is known, part of the nutrients received or formed by a cell is spent on maintaining its vital activity, part is necessary for the cell to divide, and the rest is transferred by it “to the common pot”, that is, it is sent to maintain other cells and tissues.
It is customary to distinguish the following biological functions performed by lipids:

1. Structural.
2. Barrier (protective).
3. Energy.
4. Storage (reserve).
5. Thermal insulation.
6. Lubricating.
7. Electrical insulating.
8. Regulatory (hormonal, enzymatic).
9. Transport.
10. Nutritious.
11. Signal.

Let's look at just a few of them.

Structural

The structural function of fats is that they are directly involved in the structure of the cell wall (outer membrane), which protects the cell from the environment. The hydrophobicity of lipids and their property of not dissolving in water comes in very handy here. The protective cell membrane in its structure is a double layer, consisting of 50% proteins and 50% fats. Such building materials in our body are primarily phospholipids, as well as cholesterol, glycolipids, and lipoproteins.
The structural (construction) function of fats provides the cell with the ability to maintain its shape and regulate metabolic processes with other tissues and environment. Honeycombs, as well as the surface layer (cuticle) of some plants, consist of wax, which does not allow water to pass through and, thus, provides protection against moisture getting inside (in the first case) and evaporation (in the second case). Thus, the structural function of lipids is inextricably linked with the barrier function and can be considered not only at the level of the structure of an individual cell.

Energy

The energy function of lipids is no less important. When broken down, fats release a very large amount of energy necessary for our body and its organs to perform their functions.

Important! Everyone knows that the main source of energy for a living organism is glucose, however, the share of lipids in this process is quite significant: thanks to them we receive almost a third of our “charge”.

The important role of fats is also that they represent a kind of “warehouse” for storing energy: once they enter a cell with blood, they are deposited in it in the form of fat droplets, after which, if necessary (for example, during a serious physical activity) the body can only “look into the bins” and get the necessary recharge from there.
It is this ability to reserve energy in the form of fat deposits that allows many animals, when hibernating, to go without food for several months. A seed germinates according to the same principle: until the young plant forms its own root system, it feeds on the lipids it contains (it is not surprising that the seeds of many plants contain so much oil that they are used as raw materials for its industrial production).

Thermal insulation

Above, we have already mentioned the barrier function of lipids, which allows us to protect the cell from moisture penetration (or, conversely, from its loss). But fats also help keep cells warm.

Did you know? Fat reserves in different representatives of fauna are distributed in the body differently. Thus, in a camel they are concentrated in the hump, in fat-tailed sheep - in the tail area, and in whales, seals and other Arctic marine mammals - they are distributed throughout the body. This is explained by the fact that in the first two cases, fat deposits are needed mainly to maintain “internal reserves” (energy and storage function), and in the latter - also for thermal insulation, because a fur coat is cold water- “outfit” is completely inappropriate.

Along the way, we note another manifestation of the barrier function of lipids: the layer of fat that envelops organs such as the kidneys and intestines in the human body provides them with additional protection from accidental mechanical damage.

Lubricating

This feature is sometimes also called water repellent. We have already mentioned one of its manifestations using the example of a honeycomb. The hydrophobicity of lipids does not allow water to be distributed over their surface; moisture seems to be shaken off, collecting into small droplets. Bird feathers, animal hair and human skin are covered with a thin wax layer that gives elasticity and protects against getting wet. Each of us has seen how easily a dog gets out of the water from excess moisture: it just needs to shake itself off vigorously.
Try drying a moisture-absorbing material (such as a beach towel) in the same way, and the water-repellent role of lipids will become obvious. By the way, this is why it is very harmful to frequently bathe pets (cats and dogs): along with soap, the protective fat layer is washed off from their skin, and along with it the invisible barrier to the penetration of various harmful substances through it is destroyed.

Regulatory

It would be wrong to say that lipids play a primary role in basic biological processes. Nevertheless, their regulatory function is still obvious, although indirect. If lipids do not directly regulate vital processes, they do so as components of other substances, in particular hormones and enzymes.
As examples of how this function works, it is enough to give just a few facts:

• cholesterol is the basis for the formation of such important hormones as testosterone, progesterone and a number of other sex hormones;
• necessary to ensure phosphorus metabolism;
• Another hormone of “lipid” origin is cortisone, this substance is also called the adrenal hormone.

Important! One of possible reasons stroke is a failure in lipid metabolism.

From what has been said, it becomes completely clear that the lack of certain lipids in the body will inevitably lead to the fact that many vital processes in it will begin to “slip”, thus, we need fats, among other things, as a kind of regulator.

Separately about increasing buoyancy

Speaking about the function of lipids in a cell, we have already mentioned that large marine mammals have large reserves of fat, which allow them not to freeze (more precisely, to retain their own body heat) in cold water. However, there is another reason why nature endowed these animals with this property.

As you know from a school physics course, a body in water is subject to a buoyancy force equal to the mass of the liquid it displaces. This law directly affects such a concept as buoyancy. The greater the difference between the specific gravity of the water and the specific gravity of the body (“swimmer”) immersed in it, the higher this state. If the specific gravity of a body is less than the specific gravity of water, the object floats to the surface (positive buoyancy); if it is greater, it sinks (negative buoyancy).
But what does this have to do with lipids? It turns out that it is the most direct! The specific weight of the body depends on two factors: the actual weight of the tissues, as well as the degree to which the lungs are filled with oxygen. In turn, tissues, if we are talking about mammals, for example, consist of bones, muscles and fat. Moreover, the heaviest component in us is bones, and the lightest is fat. In other words, an increase in body volume due to fat deposits reduces its specific gravity, and therefore increases buoyancy.

Did you know? Women and children aged 10 to 12 years have a lower specific body weight than men, so they are more buoyant. This is directly related to the larger amount of adipose tissue in this category.

In nature, this property is used not only by the marine mammals mentioned above, but also by other living organisms living in water (fish and even some types of algae). By increasing the fat layer, these representatives of flora and fauna are able to stay in the water column, making much less effort (energy expenditure). Thus, the importance of lipids in living nature is difficult to overestimate. This should definitely be remembered by those who, in pursuit of a slim figure, force their bodies to eat low-fat diets, without realizing what irreparable damage they are doing to their health.

Which are needed by all living things. In this article we will look at the structure and functions of lipids. They vary in both structure and function.

Lipid structure (biology)

A lipid is a complex organic chemical compound. It consists of several components. Let's look at the structure of lipids in more detail.

Simple lipids

The structure of lipids of this group provides for the presence of two components: alcohol and fatty acids. Typically, the chemical composition of such substances includes only three elements: carbon, hydrogen and oxygen.

Varieties of simple lipids

They are divided into three groups:

• Alkyl acylates (waxes). These are esters of higher fatty acids and mono- or dihydric alcohols.
• Triacylglycerols (fats and oils). The structure of lipids of this type provides for the presence of glycerol (trihydric alcohol) and residues of higher fatty acids.
• Ceramides. Esters of sphingosine and fatty acids.

Complex lipids

Substances in this group do not consist of three elements. In addition to them, they most often include sulfur, nitrogen and phosphorus.

Classification of complex lipids

They can also be divided into three groups:

• Phospholipids. The structure of lipids of this group provides, in addition to residues and higher fatty acids, the presence of phosphoric acid residues, to which additional groups of various elements are attached.
• Glycolipids. These are chemicals formed when lipids combine with carbohydrates.
• Sphingolipids. These are derivatives of aliphatic amino alcohols.

The first two types of lipids, in turn, are divided into subgroups.

Thus, varieties of phospholipids can be considered phosphoglycerolipids (contain glycerol, two fatty acid residues and an amino alcohol), cardiolipins, plasmalogens (contain an unsaturated monohydric higher alcohol, phosphoric acid and amino alcohol) and sphingomyelins (substances that consist of sphingosine, fatty acid, phosphoric acid and the amino alcohol choline).

Types of glycolipids include cerebrosides (in addition to sphingosine and fatty acids, they contain galactose or glucose), gangliosides (contain an oligosaccharide of hexoses and sialic acids) and sulfatides (sulfuric acid is attached to the hexose).

The role of lipids in the body

The structure and functions of lipids are interrelated. Due to the fact that their molecules simultaneously contain polar and nonpolar structural fragments, these substances can function at the phase boundary.

Lipids have eight main functions:

1. Energy. Through the oxidation of these substances, the body receives more than 30 percent of all the energy it needs.
2. Structural. The structural features of lipids allow them to be an important component of membranes. They are part of membranes, line various organs, and form membranes of nerve tissue.
3. Storage. These substances are a form of storage of fatty acids by the body.
4. Antioxidant. The structure of lipids allows them to perform this role in the body.
5. Regulatory. Some lipids mediate hormones in cells. In addition, some hormones are formed from lipids, as well as substances that stimulate immunogenesis.
6. Protective. The subcutaneous layer of fat provides thermal and mechanical protection to the animal's body. As for plants, waxes form a protective coating on the surface of leaves and fruits.
7. Informational. Ganglioside lipids provide contacts between cells.
8. Digestive. Cholesterol is formed from the lipid involved in the process of food digestion.

Lipid synthesis in the body

Most substances in this class are synthesized in the cell from the same starting substance - acetic acid. Hormones such as insulin, adrenaline and pituitary hormones regulate fat metabolism.

There are also lipids that the body is not able to produce on its own. They must enter the human body with food. They are found mainly in vegetables, fruits, herbs, nuts, cereals, sunflower and olive oils and other products of plant origin.

Lipids-vitamins

Some vitamins, by their chemical nature, belong to the class of lipids. These are vitamins A, D, E and K. They must enter the human body with food.

in organism

Vitamin	Functions	Manifestation of deficiency	Sources
Vitamin A (retinol)	Participates in the growth and development of epithelial tissue. It is part of rhodopsin, a visual pigment.	Dryness and flaking of the skin. Visual impairment in poor lighting.	Liver, spinach, carrots, parsley, red pepper, apricots.
Vitamin K (phylloquinone)	Participates in calcium metabolism. Activates proteins responsible for blood clotting and takes part in the formation of bone tissue.	Ossification of cartilage, bleeding disorders, deposition of salts on the walls of blood vessels, bone deformation. Vitamin K deficiency is very rare.	Synthesized by intestinal bacteria. Also found in lettuce, nettle, spinach, and cabbage leaves.
Vitamin D (calciferol)	Takes part in calcium metabolism, formation of bone tissue and tooth enamel.	Rickets	Fish oil, egg yolk, milk, butter. Synthesized in the skin under the influence of ultraviolet radiation.
Vitamin E (tocopherol)	Stimulates immunity. Participates in tissue regeneration. Protects cell membranes from damage.	Increased permeability of cell membranes, decreased immunity.	Vegetables, vegetable oils.

So we looked at the structure and properties of lipids. Now you know what these substances are, what the differences are between different groups, what role lipids play in the human body.

Conclusion

Lipids are complex organic substances that are divided into simple and complex. They perform eight functions in the body: energy, storage, structural, antioxidant, protective, regulatory, digestive and informational. In addition, there are lipid vitamins. They perform many biological functions.

general characteristics and classification of lipids

I. LIPIDS - organic substances characteristic of living organisms, insoluble in water, but soluble in organic solvents (carbon disulfide, chloroform, ether, benzene), giving hydrolysis of high molecular weight fatty acids. Unlike proteins, nucleic acids and polysaccharides, they are not high-molecular compounds, their structure is very diverse, they have only one common feature - hydrophobicity.

Lipids perform the following functions in the body:

1. energy - are reserve compounds, the main form of energy and carbon storage. When 1 g of neutral fats (triacylglycerols) is oxidized, about 38 kJ of energy is released;

2. regulatory– lipids are fat-soluble vitamins and derivatives of some fatty acids that are involved in metabolism.

3. structural - are the main structural components of cell membranes, form double layers of polar lipids into which enzyme proteins are embedded;

4. protective function:

Ø protects organs from mechanical damage;

Ø participates in thermoregulation.

The formation of fat reserves in the body of humans and some animals is considered an adaptation to irregular nutrition and living in a cold environment. Animals that hibernate for a long time (bears, marmots) and are adapted to living in cold conditions (walruses, seals) have a particularly large reserve of fat. The fetus has virtually no fat and appears only before birth.

Based on their structure, lipids can be divided into three groups:

Ø simple lipids - these include only esters of fatty acids and alcohols. These include: fats, waxes and steroids;

Ø complex lipids - they contain fatty acids, alcohols and other components of various chemical structures. These include phospholipids, glycolipids, etc.;

Ø lipid derivatives are mainly fat-soluble vitamins and their precursors.

In animal tissues, fats are in a partially free state, in to a greater extent they form a complex with proteins.

By chemical composition, structure and function performed in a living cell, lipids are divided into:

II. Simple lipids are compounds consisting only of fatty acids and alcohols. They are divided into neutraol acylglycerides (fats) and waxes.

Fats– reserve substances that accumulate in very large quantities in the seeds and fruits of many plants are part of the human body, animals, microbes and even viruses.

According to the chemical structure, fats are a mixture of esters (glycerinodes) of the triatomic alcohol glycerol and high molecular weight fatty acids - built according to the type:

CH 2 -O-C-R 1

CH 2 -O-C-R 3

where R1, R2, R3 are radicals of high molecular weight fatty acids.

Fatty acids are long-chain monocarboxylic acids (containing 12 to 20 carbon atoms).

Fatty acids that make up fats are divided into saturated (do not contain double carbon-carbon bonds) and unsaturated or unsaturated (contain one or more double carbon-carbon bonds). Unsaturated fatty acids are divided into:

1. monounsaturated – contain one bond:

2. polyunsaturated – contain more than one bond.

Of the saturated acids, the most important are:

palmitic (CH 3 – (CH 2) 14 – COOH)

stearic (CH 3 – (CH 2) 16 – COOH);

The most important of the unsaturated fatty acids are oleic, linoleic and linolenic.

CH 3 – (CH 2) 7 – CH = CH– (CH 2) 7 – COOH – oleic acid

CH 3 – (CH 2) 4 – CH = CH – CH 2 – CH = CH – (CH 2) 7 – COOH – linoleic acid

CH 3 –CH 2 –CH=CH–CH 2 –CH=CH–CH 2 –CH=CH–(CH 2) 7 – COOH – linolenic

The properties of fats are determined by the qualitative composition of fatty acids, their quantitative ratio, the percentage of free fatty acids not bound to glycerol, etc.

If the fat composition is dominated by saturated (marginal) fatty acids, then the fat has a solid consistency. On the contrary, unsaturated (unsaturated) acids predominate in liquid fats. Liquid fats are called oils.

An indicator of the saturation of fat is the iodine value - the number of milligrams of iodine that can join 100 g of fat at the site where the double bonds in the molecules of non-ideal acids are broken. The more double bonds in a fat molecule (the higher its unsaturation), the higher its iodine number.

Another important indicator is the saponification number of fat. When fat is hydrolyzed, glycerol and fatty acids are formed. The latter form layers with alkalis called soaps, and the process of their formation is called saponification of fats.

The saponification number is the amount of KOH (mg) used to neutralize the acids formed during the hydrolysis of 1 g of fat.

A feature of fats is their ability to form aqueous emulsions under certain conditions, which is important for nourishing the body. An example of such an emulsion is milk, the secretion of the mammary glands of mammals and humans. Milk is a thin emulsion of milk fat in its plasma. 1 mm 3 of milk contains up to 5-6 million milk fat globules with a diameter of about 3 microns. Milk lipids consist predominantly of triglycerides, in which oleic and palmetic acids predominate.

Polyunsaturated fatty acids (oleic, linoleic, linolenic and arachidonic acids) are called irreplaceable (essential), because they are necessary for man. Polyunsaturated fatty acids promote the release of cholesterol from the body, preventing and weakening atherosclerosis, and increase the elasticity of blood vessels.

Due to the fact that unsaturated fatty acids have double bonds, they are very easily oxidized. The process of fat oxidation can occur on its own due to the addition of atmospheric oxygen at the site of double bonds, but it can be significantly accelerated under the influence of the enzyme lipoxygenase.

Waxes– esters of high molecular weight fatty acids and monohydric alcohols with a long carbon chain. These are solid compounds with pronounced hydrophobic properties. Fatty acids contain from 24 to 30 carbon atoms, and high-molecular alcohols contain 16-30 carbon atoms.

R 1 – CH 2 – O – CO – R 2

The main function of natural waxes is the formation of protective coatings on the leaves, stems and fruits of plants, which protect the fruits from drying out and damage by microorganisms. Honey is stored under a beeswax cover and bee larvae develop. Lanolin is a wax of animal origin that protects hair and skin from water.

Steroids– esters of cyclic alcohols (sterols) and higher fatty acids. They form the saponified fraction of lipids.

The saponified fraction of lipids is formed by sterols.

II . Complex lipids

Phosphatides (phospholipids) - fats containing phosphoric acid associated with a nitrogenous base or other compound ( IN).

CH 2 -O-C-R 1

CH 2 -O- P = O

If IN is a choline residue, the phosphatide is called lecithin; if colamine - cofaline. Lecithin predominates in grains and seeds; cephalin accompanies it in small quantities.

Lipids- a collection of organic substances. Found in living organisms and divided into classes of lipids. Lipids are insoluble in water, but can dissolve in ether, chlorophore and benzene. The structure and function of lipids include many chemical compounds; they have the function of storing energy. Steroids and Phospholipids are included in , other lipids, of which there are slightly fewer, may be coenzymes, electron carriers, light absorbing pigments, hormones, hydrophobic “anchors” that contain membrane proteins.

The human body has the ability to break down lipids, although many of these substances must enter the body, these are (omega-3, omega-6)

Lipid groups

Lipids are divided into simple and complex. Elements include esters of fatty acids; complex lipids, in addition to fatty acids and alcohol, contain hydrocarbons, phosphates, lipoproteins and others. Each group is designated by two in English letters:

Glycerophospholipids (GP)

Glycerolipids (GL)

Polyketides (PK).

Sphingolipids (SP);

Steroid lipids (ST)

Prenolni lipids (PR);

Fatty acids (FA)

Sugar lipids (SL);

Chemical composition of lipids

Glycolipids

Glycolipids are a class of lipids containing mono- or oligosaccharide residues. They can be either glycerol or sphingosine derivatives.

(TG) Acylglycerides - glycerides are esters of trihydric alcohol and fatty acids. Hydroxyl classes in the molecule are further divided into groups:

1. triglycerides
2. diglycerides
3. monoglycerides

The most commonthese are triglycerides. They are also called fats. Fats can be simple, containing fatty acids, but mixed fats are more common; they also contain fatty acids. Properties triglycerides depend on its fatty acid composition, for example, the more unsaturated acids, the higher their melting point. Take butter as an example, it contains almost 95% unsaturated fatty acids and melts at room temperature. Animal fats, for example, lard, with room they retain weight at temperature, which is why everything is exactly the opposite for them (the content of saturated fatty acids)

Glycerophospholipids

The formula of glycerophospholipids is R1 and R2 fatty acids, X is the residue of the substance AZT. Glycerophospholipids are also called phosphoglycerides; they produce phosphatidic acids, which in turn consist of glycerin . In it, the first and second groups include R1, R2, and the third group includes phosphate acids; radical X (nitrogen-containing) is already added to it

Fatty acids form the hydrophobic part of glycerophospholipids in the molecule. The phosphate part in a neutral environment carries a negative charge, and nitrogen-containing compounds carry a positive charge; in a nitrogen-containing environment it can be negatively charged, which is why it is sometimes called polar. In an aqueous environment, phosphoglycerols produce micelles, their heads turned outward and their tails inward.

Common membrane phosphoglycerides are lethicin, in which the X radical is a residue of choline and phosphatidylethanolamine. There are also nitrogen-free glycerophospholipids, which include X, inositol and alcohol. Double phosphoglycerides were found in the inner membrane of the mitochondrion. In animals, essential lipids enrich heart, this group of compounds also includes active activation substances platelets.

Glyceroglycolipids

Glyceroglycolipids are a class of diacylglycerols with a carbon atom to which a glycosylmine is attached. The mostwidespreadThe class of lipids is galactolipids, they contain galactose residues. They make up 80% of membrane lipids. Together with galactolipids, a glucose residue can be found in plant membranes

Sphingoglycolipids

Cerebrosides are sphingoglycolipids, the hydrophilic part of which is represented by a monosaccharide residue, usually glucose or galactose. Galactocerebrosides are distributed in neuronal membranes.

Globosides are oligosaccharide derivatives of ceramides. Together with cerebrosides, they are called neutral glycolipids because at pH 7 they are uncharged.

Gangliosides are complex glycolipids, their hydrophilic part is represented by oligosaccharides, at the end of which there is always one or more N-acetylneuraminic (sialic) acid residues, due to which they have acidic properties. Gangliosides are the most common inganglion membranes neurons.

Sphingophospholipids

Structural formula of sphingomyelin in part of it component includes ceramide, which contains long-chain amino alcohols and 1 fatty acid residue, a hydrophilic radical, which in turn connected to sphingosine. found in membrane cells, but nervous tissue is considered the richest. Much of their content is also found in axons, which is where their name comes from.

Phospholipids

The structural classes of lipids are phospholipids; a common feature of phospholipids is their amphiphilicity, and it has a hydrophilic and hydrophobic part. Therefore, they can form micelles and bilayers in an aqueous environment.

Steroids

A steroid is a class of natural lipids, it containscyclopentane perhydrophenanthrenecore. These include alcohols with the hydroxyl class in the 3rd position, sterols with fatty acids - sterides. In animals, the most common sterol is cholesterol, which is also part of the membranes.

Steroids perform many functions in different organisms. For sex hormones, adrenal glands , vitamin functions and others.