Carbohydrate Chemistry: Monosaccharides and Polysaccharides

Consist of covalently linked monosaccharide units, often associated with proteins (glycoproteins) and lipids (glycolipids) with structural and regulatory functions.

Composed of more than 10 molecules of monosaccharides on hydrolysis, with a general formula of (C6H10O5)n.
Have molecular masses ranging into millions of daltons and serve indispensable structural functions in all types of organisms.
Most conspicuous in plants, where cellulose comprises up to 80% of dry matter.

Divided into two groups: homopolysaccharides (homoglycans) and heteropolysaccharides (heteroglycans).
Homopolysaccharides: polymers of same monosaccharide units, e.g. starch, glycogen, inulin, cellulose, dextrins, and dextrans.
Heteropolysaccharides: polymers of different monosaccharide units or their derivatives, e.g. mucopolysaccharides (glycosaminoglycans).

Isomerism: due to asymmetric carbon atoms, compounds can exhibit stereoisomerism, resulting in isomers with identical composition but differing only in spatial configuration.
D-Series and L-Series: the orientation of H and OH groups around the carbon atom determines whether a sugar belongs to D-series (OH group on the right) or L-series (OH group on the left).
Most monosaccharides in mammals are D-sugars, and enzymes responsible for their metabolism are specific for this configuration.

Carbohydrates or saccharides (Greek: sakcharon, sugar) have a chemical composition of “carbon hydrate” (CH2O)n, where n ≥ 3.
Essential and most abundant class of biological molecules, with the basic units being monosaccharides.
Aldehyde or ketone derivatives of higher polyhydric alcohols or compounds that yield these derivatives on hydrolysis.

Divided into four major groups: monosaccharides, disaccharides, oligosaccharides, and polysaccharides.

Also known as simple sugars, cannot be hydrolyzed further into simpler forms.
Aldehyde or ketone derivatives of straight-chain polyhydroxy alcohols containing at least three carbon atoms, with a general formula of CnH2nOn.

Hydrolysis produces two molecules of the same or different monosaccharides, with a general formula of Cn(H2O)n-1.
Examples include maltose, lactose, sucrose, and lactulose.

Presence of asymmetric carbon atoms confers optical activity on compounds.
Dextrorotatory (D or + sign) and laevorotatory (L or – sign) compounds rotate plane-polarized light to the right or left, respectively.
Racemic mixtures: equal amounts of dextrorotatory and laevorotatory isomers, resulting in no optical activity.
Resolution: separation of optically active isomers from a racemic mixture.

Formation of cyclic structures from open-chain forms of monosaccharides, resulting in anomers.
Anomeric carbon atom: the carbon atom that becomes asymmetric after cyclization, leading to the formation of different anomers.

Presence of asymmetric carbon atoms confers optical activity on a compound.
When a beam of plane-polarized light is passed through a solution exhibiting optical activity, it will be rotated to the right (dextrorotatory, D or + sign) or left (laevorotatory, I or – sign).
A racemic mixture contains equal amounts of dextrorotatory and laevorotatory isomers, resulting in no optical activity.
Resolution is the separation of optically active isomers from a racemic mixture.

The reaction between an aldehyde group and an alcoholic-OH group on the same molecule forms a cyclic structure.
This reaction can form two different forms of glucose: α-D-Glucose (OH group extends to the right) and β-D-Glucose (OH group extends to the left).
Carbon-1 becomes asymmetric after cyclization and is called an anomeric carbon atom.
Compounds related in this way are called anomers.

Carbohydrates have both structural and regulatory functions in biological systems.
They are associated with proteins (glycoproteins) and lipids (glycolipids).
Polysaccharides consist of many covalently linked monosaccharide units and have molecular masses ranging from millions of daltons.

Polysaccharides are composed of more than 10 molecules of monosaccharides on hydrolysis.
General formula: (C6H10O5)n.
They have indispensable structural functions in all types of organisms.
Polysaccharides are further divided into two groups: homopolysaccharides (homoglycans) and heteropolysaccharides (heteroglycans).

Homopolysaccharides are polymers of the same monosaccharide units, e.g., starch, glycogen, inulin, cellulose, dextrins, and dextrans.
Heteropolysaccharides are polymers of different monosaccharide units or their derivatives, e.g., mucopolysaccharides (glycosaminoglycans).

Isomerism: the presence of asymmetric carbon atoms in a compound gives rise to the formation of isomers.
Stereoisomerism: compounds that are identical in composition and differ only in spatial configuration.
D-Series and L-Series: the orientation of the H and OH groups around the carbon atom determines the series.

Carbohydrates are also known as saccharides (Greek: sakcharon, sugar).
They have the general formula (CH2O)n, where n ≥ 3.
The basic units of carbohydrates are monosaccharides.
Carbohydrates are essential and the most abundant class of biological molecules.

Carbohydrates are divided into four major groups: monosaccharides, disaccharides, oligosaccharides, and polysaccharides.
Monosaccharides are also known as simple sugars and cannot be hydrolyzed further into simpler forms.
They have the general formula CnH2nOn.