Building Blocks of Carbohydrates: The basic biochemistry of living organisms can, therefore, be understood regarding the morphology and physiology of the four biological macromolecules: carbohydrates, proteins, lipids, and nucleic acids.

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Among these four macromolecules, carbohydrates are considered to be the most abundant as they serve as the immediate sources of energy of living organisms.

The word “carbohydrate” comes from the two Greek words “carbo” and “hydro” which mean “carbon” or “coal” and “water” respectively. This probably came to the fact that when sugars are heated, carbon and water are released. In biochemical terms, they are referred to as either polyhydroxy aldehydes or polyhydroxy ketones.

But what exactly make up these complex macromolecules tha e them to carry out such functions? In this article, let’s explore about these carbohydrates and their biological building blocks: the monosaccharides.

Table of Contents

Three Most Common MonosaccharidesPolysaccharides

Building Blocks of Carbohydrates

Physical and Chemical Properties of Monosaccharides

Monosaccharides (Source: Wikimedia)

Monosaccharides are known to be the simplest form of carbohydrates, and as such, they are considered to be their building blocks.

The term “monosaccharide” comes from the Greek word “mono” which means “one” and “saccharide” which means “sugar” or “sweetness.”

This is because monosaccharides contain only one unit of polyhydroxy aldehyde or ketone and are grouped according to the number of carbon they have.

In general, monosaccharides, share the same chemical formula of C6H12O6, and because having six carbon atoms, they are also called as hexose.Being sugars, monosaccharides naturally have a sweet taste (fructose is considered to be the sweetest among them) and remain in their solid forms at room temperature.In spite of their very high molecular weights, they are very soluble in water as compared with other substances with the same molecular weight. The fact that there are a lot of OH groups in their structure makes this possible.Regarding their chemical composition, monosaccharides do not usually exhibit their open-chain structures. In this type of formation, an alcohol group can be readily added to the carbonyl group to create a pyranose ring that contains a stable conformation of a cyclic hemiacetal or hemiketal.

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Monosaccharides, in general, can be readily oxidized by certain chemicals. The aldehydes and ketones in their structures contain OH groups located on the carbon next to the carbonyl group that can react with the cupric ions (Cu) of Benedict’s reagent. After this reaction, a formation of an orange precipitate of copper (I) oxide or Cu2O will occur.

All monosaccharides undergo this type of reaction and are called reducing sugars. (The chemical reaction is shown above)