CARBON HYDRATES
Introduction. Carbohydrates are the most abundant and those that provide the most energy through catabolic metabolism (Krebs cycle or glycolysis). They serve as energy storage, that is, they are reserve polymers, such as starch (plants) and glycogen (plant).
In addition, they have a structural function, since they serve as a support for the cell, like cellulose in the case of plants or chitin in insects and crustaceans or peptidoglycans in bacterial walls. They are also precursors to the synthesis of other molecules, such as lipids (fatty acids) and proteins.
From the energy point of view, we must ingest about 2,000 kcal of carbohydrates that will produce 55% of daily calories.
We can distinguish between fast-digesting carbohydrates, such as monosaccharides or disaccharides, which are simple sugars and pose a danger to diabetics, as they are quickly absorbed.
They can also be called simple carbohydrates, since they are composed of one or two molecules, so they can be oligosaccharides, monosaccharides (sugar, honey) or disaccharides (sucrose, lactose and maltose).
On the other hand, we find slow-digesting carbohydrates, such as starch or polysaccharides, since many bonds have to be broken to absorb them. Therefore, they are absorbed within 2 hours of being ingested.
They can also be called compound carbohydrates, which are long chains of molecules, where cellulose (forms the plant wall), starch and glycogen, that is, the carbohydrates of cereals, stand out. Therefore, diabetics should take 60% slow- digesting carbohydrates.
Classification. Carbohydrates are compounds formed by C, H and O in proportion (C1H2O1) n, although, on rare occasions, they can also present other compounds,
1
such as N or S. In the human body carbohydrates that are made up of 5 or 6 carbons.
They present a hydrocarbon chain with multiple hydroxyl groups (-OH), in addition
(aldose) or inside the chain, giving rise to a ketine group ( ketosis).
Carbohydrates can be divided into:
> You dares. They are simple carbohydrates (monosaccharides) that cannot be
intermediates), tetroses (metabolic intermediates), pentoses (DNA and RNA Pentoses pathway), hexoses (main metabolites) (main metabolites) and heptoses (important in photosynthesis).
> Bold.They are made up of monosaccharide groups and can be hydrolyzed. They can be divided into:
Holosids.They are formed only by repetitions of bears
Oligosaccharides They are made up of less than 10 bears, such as disaccharides or trisaccharides.
Polysaccharides. They. are formed by a high number of monosaccharides. They can be homopolysaccharides (identical bears) or heteropolysaccharides (different bears).
Heterosides.They are formed by the union of carbohydrates with aglucones (non-carbohydrate part). In this case we find:
Carbohydrates and proteins. Like proteoglycans (polysaccharide + protein) or glycoproteins (protein + carbohydrate).
Carbohydrates and lipids. Like glycolipids (carbohydrate + lipid.
MONOSACARIDOS
Proteoglucanos
HIDRATOS DE CARBONO
HETEROSIDOS
Glucoproteinas
OSIDO
Glucolipidos
HOLOSIDOS
Oligosacarido
Homopolisacaridos
Polisacaridos
Heteropolisacaridos
The sugars present in nature are the D-sugars, which are those in which the penuntimo OH is on the right.
2
Mirror
Osas or monosaccharides. From a structural point of view, the base molecule is glyceraldehyde, which has an asymmetric carbon. Carbohydrates are