The carbohydrates, generally referred to as carbohydrates or sugars, are macromolecules that are present in greater quantities on our planet , and stand out as the main source of energy of our body. The animals are unable to produce these molecules, requiring therefore its intake.
→ Chemical structure of carbohydrates
We can define carbohydrates as polyhydroxyaldehydes or polyhydroxy ketones or substances that release these compounds in the hydrolysis process . Carbohydrates are made up of carbon (C), hydrogen (H) and oxygen (O ) molecules and are therefore also called carbohydrates. It is worth noting, however, that some carbohydrates have other atoms constituting their molecules. The general formula for carbohydrates is (CH 2 O) n
→ Carbohydrate classes
Carbohydrates can be classified into three main classes: monosaccharides, oligosaccharides and polysaccharides.
- Monosaccharides: theyare the simplest carbohydrate units and consist of only one unit of polyhydroxyaldehydes or ketones. They can be classified, according to the number of carbon atoms they have, in: triosis (3 carbons), tetrose (4 carbons), pentose (5 carbons), hexose (6 carbons), heptose (7 carbons) and octosis ( 8 carbons). The two most abundant monosaccharides in nature are glucose and fructose;
- Oligosaccharides:They are monosaccharides linked by glycosidic bonds and stand out for being short chains. As an example of oligosaccharides, we can mention sucrose and lactose . These two carbohydrates can also be called disaccharides, as they are composed of two monosaccharides;
- Polysaccharides:They are monosaccharides also linked by glycosidic bonding, but, unlike oligosaccharides, they have thousands of joined monosaccharides. Polysaccharide is a carbohydrate with more than 20 units. As an example of polysaccharide, we can mention cellulose, starch and glycogen .
Carbohydrates have different functions in living organisms. The following stand out:
- Energy function:Carbohydrates are used by cells for the production of ATP, thus providing energy for carrying out cellular activities. Glucose is the main carbohydrate used by cells to produce energy;
- Structural function:Some carbohydrates stand out for their structural character. This is the case with cellulose, which is the main component of the cell wall of vegetables, and chitin, a carbohydrate found in the exoskeleton of arthropods ;
- Energy reserve function:In addition to providing energy immediately, carbohydrates can be stored in different ways. In vegetables, the reserve carbohydrate is starch; in animals, the reserve carbohydrate is glycogen.
→ Sources of carbohydrates
When we talk about carbohydrate sources, we immediately think of bread, pasta, rice and cereals. However, despite being rich in these macromolecules, they are not the only ones that contain them. All products of vegetable origin have carbohydrates , therefore, fruits and vegetables are sources of this nutrient. It is also worth noting that honey, despite being of animal origin, is an example of carbohydrate.
Curiosity: The daily needs for carbohydrates are around 6 g to 7 g per kilo. Approximately 50% to 60% of the total caloric value of our diet must come from carbohydrates.