Types of biomolecules
Carbohydrates (sugars) are the most abundant among the major classes of biomolecules.
Most of the carbohydrates follow the general formula: Cn (H2O) n, from where they derive
their name, which means hydrates of carbon. However, not all carbohydrates follow this
formula and are slightly different in structure from this rule. Chemically, they are simple
organic compounds that are aldehydes or ketones with many hydroxyl groups added
usually on each carbon atom not part of the aldehyde or ketone functional group.
Saccharide is the structural (monomeric) unit of carbohydrates. Based on the number of
monomeric units, carbohydrates may be monosaccharide, disaccharide, oligosaccharide,
or polysaccharide. Monosaccharides are carbohydrates of only one simple sugar.
Examples are glucose, fructose, and galactose. They are the most fundamental type of
carbohydrates. Disaccharides are carbohydrates made up of two monosaccharide units.
Examples are sucrose, maltose, and lactose. Oligosaccharides are those consisting of two
to ten simple monosaccharide units. Examples are raffinose, maltotriose, and
maltotetraose. Those with a larger number of monosaccharide units are called
polysaccharides. Examples are starch, cellulose, and glycogen. When a polysaccharide is
made up of monosaccharide units of the same type it is referred to as a
homopolysaccharide (or homoglycan) whereas a polysaccharide is comprised of more
than one type of monosaccharide it is called heteropolysaccharide (or heteroglycan).