What are lipids and what are they for?

Lipids are a set of biological molecules that are insoluble in water and contain a good amount of energy, due to their numbers of carbon-hydrogen bonds. These are an organic chemical composition that is generated in living things. They have the most varied composition, granting a gigantic diversity of biological functions.

Lipids are used to store and give us that energy that we need so much, we could say that it is their main biological function . They also serve to develop the cell membrane, help to form hormones such as estrogen and testosterone. Lipids are used in the food and cosmetic industries, among others.

What is the function of lipids?

Lipids are highly functional for science due to their great insolubility capacity, or because they are limited to fragment, obtaining the maximum benefit for the pharmaceutical industry.

Lipids in their constitution have a good amount of triglycerides, these being the main source of energy to carry out day-to-day tasks, that is, once the lipids are absorbed by the body, they are converted into energy to perform the necessary motor functions by the body.

As biomolecules, lipids also work by forming their own body’s cellular system, that is, they make up the membrane that covers the cell, in this way they manage to be the source to produce vitamins and hormones.

Another main function of lipids is based on the formation of hormones thanks to cholesterol, which is the origin of the hormonal loads of the thyroid.

Importance of lipids

Lipids are important in the diet not only because of their high energy value, but also because of the fat-soluble vitamins and essential fatty acids that are found in the fat of natural foods. Fat is located in adipose tissue, where it serves as a thermal insulator for subcutaneous tissues and around some organs.

Nonpolar lipids are important because they act as electrical insulators, which helps the rapid propagation of waves, to depolarize the entire length of myelinated nerves.

The fundamental importance of lipids for human development is in nutrition and health. Knowledge of the biochemistry of lipids is necessary to understand many pathologies, including obesity.

Lipid Classification

The classification of lipids allows us to recognize in their composition and their functionality, how they can benefit the human being.

1. According to its polarity

As chemistry points out, in a cellular element its polarity is directed to the unity of its atoms. But, this union can be stronger, at the same time that one electron has a positive charge and the other contains a negative charge, then we would be witnessing a polarity at the extremes.

• Non-polar lipids:

They are lipids that do not have ambivalent bonds or atoms in their structure, and that for this reason cannot be diluted in water. These lipids have the particularity that they can be used, to be carried in other components, since they are insoluble. Non-polar lipids are used in the content of vitamins.

• Polar lipids:

This time we are dealing with doubly compound lipids, since their biomolecular content allows us to see the non-polar and polar bonds, which through the provision of liquids and solvents allows the lipid to be regularly soluble. Consequently, when there is a solvent, these lipids not only manage to be transferred, but also dissolve, thus releasing some of their elements.

2. According to its saponifiable condition

Saponification is a step that can only be carried out at the industrial level, since this process means including hydrates in solution that allow the disintegration of fatty acids, leaving them in a liquid or solution state.

• Saponifiable lipids.

These lipids are strongly composed of fatty acids, which largely requires disintegration. They are also those that can withstand the effects of hydrolysis, which is nothing more than the process of disintegration of a substance produced by water. 

• Non-saponifiable lipids.

They are lipids that consist of a good amount of carbon molecules, in the same way they turn out to be derived from fatty acids, but even so they are not composed of these, hence it is impossible to apply the hydrolysis process to them.

Their particular content has made them privileged in the pharmaceutical industry, since they cannot be easily diluted, but they can be rebuilt and in this way contribute to the recovery of all muscle and tendon wear that may occur.

3. Simple or Complex

According to studies of lipids by their own composition, they can be divided into simple and complex.

• Simple lipids.

They are the least complex in their cellular structure, and cannot be decomposed by chemical or solvent processes, but they can be fragmented under very limited conditions. Simple lipids are those that do not have fatty acids but do have the component of steroids. 

• Complex lipids.

These lipids are made up of fatty acids, alcohol, among other chemical functions such as glycerides, phospholipids, glycolipids, and waxes.

Next, let’s see what each of these complex lipids refer to:

Fatty acids: are made up mostly of carbons, and are divided into saturated and unsaturated.

• Saturated fatty acids :

They are those that do not generate energy to the body, but are essential for the formation of membranes for the body. Saturation is based on the union or alloy of the hydrogen and carbon rings.

• Unsaturated fatty acids:

They are those, which do not have hydrogen, or if they do contain it, it is in little quantity, and this makes it easier for them to be diluted in moderate temperatures.

Glycerides: these behave like a derivative of fat, and are the result of binding with glycerin. These bind to fatty acids through ether.

Phospholipids: these are a type of lipids that have polarity at their terminations, which when in contact with a solvent establish ionic bonds.

Glycolipids: they are lipids that are derived from sphingosine, having a high content of sugar or glucose.

Waxes – These are the result of combining fatty acid with a higher alcohol. They are not soluble in liquids and have an impermeability condition.

Properties of lipids

Lipids can be divided into two types of physical and chemical properties.

Physical properties

• Solubility:

Soluble in organic solvents and insoluble in water.

• Density:

It is lower than water.

• Melting point:

Fats that are made up of saturated fatty acids have a higher melting point than those made of unsaturated or short-chain fatty acids.

• Smell, color and taste:

Glycerides that are pure do not have color, taste, or smell.

• Emulsion:

If triglycerides are incorporated with water and they move, an emulsion is formed that is momentary, because it reduces as soon as it stops moving.

Chemical properties

• Hydrolysis:

It is the separation of the molecules. Glycerides, by hydrolysis, break up into their components. It is the adverse reaction to esterification. Glycerides are hydrolyzed by superheated steam, by enzymes, and by acids.

• Saponification:

It is when you heat the fats with an alkaline compound, glycerol and soaps are produced.

• Rancidity:

It is produced by the oxidation of unsaturated fatty acids. Oxidation can produce the breaking of the chain at the level of the double bond, releasing volatile fatty acids, which is the reason for the typical odor of oxidized fats.

• Alcoholysis:

It is the union of glycerides with alcohol. This releases glycerol and fatty acids in the form of methyl or ethyl esters.

• Hydrogenation:

This process consists of purifying and cleaning the fats, using hydrogen at high pressures and high temperatures.

What kind of lipid is cholesterol?

Triglycerides, phospholipids and lipids have sterols, one of which is cholesterol, which is important for our body. It is a complement to cell membranes, it is the predecessor in the synthesis of elements such as vitamin D and sex hormones, among others, and it participates in metabolic processes.

Cholesterol is transported in the blood by various lipoproteins. Some take the job of removing the excess cholesterol and taking it to the liver and then being expelled through the feces. There are HDL (high-density lipoproteins), consisting primarily of proteins and a small amount of cholesterol. These are what we call good cholesterol.

There are other proteins called LDL (low-density lipoproteins), consisting primarily of cholesterol, these are responsible for transporting cholesterol to cells and tissues, and when there are too much they deposit it on the walls of the arteries. LDL is said to lead to bad cholesterol, and its abundance can compromise heart health. A balance between the two HDL and LDL fractions is important.

Conclusion on lipids

Lipids make up cellular structures that are important for the development of life, and although we think that they are harmful, we should not eliminate them from the daily diet, we only have to balance them. The most important biological molecules are lipids, carbohydrates, proteins and nucleic acids.

Lipids make up a group of heterogeneous elements that are responsible for fulfilling various functions in living beings. The most important lipids are: fats, oils, waxes, phospholipids, sphingolipids, glycolipids, terpenes and steroids. Among them, the most important are sterols, especially cholesterol, which fulfills several important functions for living beings.