The term carbohydrate is used to describe those molecules that fundamentally have a structure consisting of hydrogen, oxygen and carbon. They are biomolecules and their first function in living beings is to provide energy for them to carry out all the physical and metabolic tasks necessary to survive. Along with proteins and lipids, it is the most abundant substances in nature. The composition of hydrocarbon molecules have a lower proportion of oxygen, being mostly hydrogen and carbon atoms, they also have covalent bonds, the strongest between two ions.

what is carbohydrates

The origin of the word dates back to the 19th century due to a confusion in the interpretation of a chemical formula, the term is maintained but it is not very appropriate because the molecule is not carbon atoms linked to water molecules but a combination between these and other functional molecules, considering the most appropriate name to be carbohydrate, which comes from the Greek σάκχαρ meaning sugar or sweet and is used to describe derivatives of glucose by polymerization and loss of water.

Carbohydrates can be divided into four groups, the monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Monosaccharides are made up of a single molecule, it is the simplest form of carbohydrates and cannot be hydrolyzed.

Disaccharides are made up of two monosaccharides and this group includes hydrocarbons commonly found in the natural environment such as sucrose (sugar), lactose (milk sugar), maltose (from barley fermentation) and fructose.

Oligosaccharides are made up of three or nine monosaccharide molecules and polysaccharides are structures made up of more than ten monosaccharides, these can be branched or not and correspond to substances such as starch and glycogen, among others.

If the energy of a hydrocarbon is not used by the body, it will store it in the form of fat until it is required, thus being a very important factor in terms of nutrition, causing this necessary group of foods to be avoided in treatments against obesity. .

Within the synonyms of this term, are carbohydrates, saccharide, carbohydrate and sugar. There is a lot of information on this term on the web and it can be found as pdf carbohydrates.

Characteristics of carbohydrates


Carbohydrates or carbohydrates are known to be biomolecules, in fact, one of the most abundant in living beings and are made up of a series of chains, which are formed from oxygen, hydrogen and carbon. One of the most striking characteristics is that it has a sweet taste and gives energy to the body.

The formula of carbohydrates is Cn H2n On, in addition, they have chemical bonds, but the atoms are covalent, this makes the breaking process extremely difficult.

Each molecule with links of this type has a lot of energy, which is used with the intervention of a series of oxygen molecules. In addition to being a source of energy, they are part of the structure of plants because they have both soluble and insoluble fibers and are reducing sugars.

carbohydrate structure

Like the rest of the biomolecules, there is a classification of carbohydrates, these are based on 3 elements, that is, hydrogen, carbon and oxygen. All these elements are distributed in two chemical groups that give the characteristics to carbohydrates, the first group is the carbonyl group and the second is the hydroxyl group. The first is located in ketones and aldehydes, the second in alcohols.

The carbohydrate can be an aldehyde only if the carbonyl group is located at one end, but if it is on the intermediate carbons then it is a ketone.

carbohydrate metabolism

It is defined as the biochemical process of breakdown, formation and conversion of carbohydrates in every living organism. Carbohydrates are the main molecules of the organism whose purpose is to provide energy to the body and this is achieved thanks to their extremely easy metabolism.

There is a fairly common carbohydrate and this is glucose, this is a monosaccharide that all living organisms known today metabolize. If one gram of carbohydrates is oxidized, approximately 4 kcal of energy are generated, that is, less than half that generated in lipids.

types of carbohydrates


This term has its own classification of carbohydrates and is divided into 4 aspects distributed among monosaccharides, disaccharides, oligosaccharides and polysaccharides.


They are white substances with a sweet taste, crystallizable and soluble in water. They are easily oxidized, turning into acids, which is why they are said to have reducing power (when they are oxidized, they are reduced to another molecule). These are the monomers of the rest of the carbohydrates, which means that all the others are formed by polymerization (joining) of these. they are simple molecules that correspond to the general formula (CH2O).

They are made up of 3, 4, 5, 6 or 7 carbon atoms. Chemically they are polyalcohols, ie carbon chains with one -OH group on each carbon, in which one carbon forms an aldehyde group or a ketone group. Within the basic examples of this aspect, are fructose, sucrose and galactose. Foods with carbohydrates from this aspect are cereals, dates, figs, apples, pineapples, etc.


These are very abundant oligosaccharides in nature, their structure is free and they originate from two different or identical monosaccharides. Carbohydrate foods that can be mentioned in this aspect are common sugar, which is found in milk, beer, honey, malt or cereals, as these are rich in sucrose, maltose and lactose.


They are the carbohydrates that are formed from the union of two or ten monosaccharides or disaccharides, but the oligosaccharides of three or more molecules are not free in their structure as in the previous aspect, on the contrary, they join the molecules of proteins or lipids. Foods rich in carbohydrates from this aspect are bananas, artichokes, garlic, onions, tomatoes, etc.


They are a series of biomolecules composed of the union of a considerable amount of monosaccharides, which represent the simplest sugars, whose particularity is that they do not hydrolyze, that is, they do not break down into other compounds.

Its function in living organisms is to provide energy and structural reserves. They are classified into: reserve polysaccharides and structural polysaccharides. The first are those that store glucose in the form of starch in vegetables and glycogen in animals, to release it to the body when necessary.

In animals, the action of polysaccharides is completed by fats or lipids that store twice as much energy. On the other hand, structural polysaccharides are those that produce organic structures.

Among those that stand out the most are cellulose, which is the main component of the cell wall of plants, and chitin, which performs the same function in fungi. An example of this aspect is starch, that is, wheat and corn flour.

function of carbohydrates

Carbohydrates fulfill different functions, the first is storage, because in fact, plants are responsible for storing energy reserves in the form of carbohydrates, where do they do it? in its roots and in the fruits. Animals also have this capacity, but they do so in glucose, which is stored in the muscles and in the liver.

They also have a structural function, since deoxyribose and ribose are carbohydrates that make up the structural part of biological macromolecules and nucleic acids, which are essential in protein synthesis and genetic transmission.

On the other hand, there is the source of energy, because in cellular respiration, the energy of glucose is released and used to form adenosine triphosphate, that is, the energy currency for the cellular reactions of living beings.

It also has a nutritional function, since there are too many carbohydrate foods that serve to maintain a healthy diet, for example, fruits, grains and vegetables, which are rich and natural sources of carbohydrates.

Having a diet without carbohydrates is difficult, because living beings need fiber and glucose to move bad cholesterol, which is why doctors recommend, in special cases, having a low-carbohydrate diet.

Finally, there is the lubricating function, which focuses on the synovial fluid that is responsible for the natural movement of the joints. This liquid has hyaluronic acid, which is made up of disaccharides.

examples of carbohydrates

As stated before, it is extremely difficult to have a diet without carbohydrates because these are found in most of the foods that human beings consume, therefore, in this aspect, a list of carbohydrates present in foods that are generally are consumed daily.

  • Vegetables and fruits: apples, pineapples, bananas, tomatoes, dates, etc.
  • Legumes: soybeans, lentils, chickpeas and peas.
  • Tubers: onion, garlic, potato, radish, corn, eggplant, etc.
  • Sugars: cane sugar, honey.
  • Cereals: barley, oats, rice, wheat, rye and corn.

Frequently Asked Questions about Carbohydrates

What are carbohydrates?

They are molecules of hydrogen, carbon and oxygen.

What are carbohydrates for?

They serve as a source of energy.

How are carbohydrates classified?

In monosaccharides, disaccharides, oligosaccharides, polysaccharides.

What foods contain carbohydrates?

Fruits, vegetables, tubers, cereals and sugars.

What do carbohydrates provide?