The most abundant biomolecules on earth are carbohydrates. From a
chemical viewpoint, carbohydrates are primarily a combination of carbon
and water, and many of them have the empirical formula (CH2O)n,
where n is the number of repeated units.
They are abundant in terrestrial ecosystems, many forms of which we use
as food sources.
These molecules are also vital parts of macromolecular structures that
store and transmit genetic information (i.e., DNA and RNA).
Their functions are:
Serve as energy stores, fuels, and metabolic intermediates.
Formation of the structural framework of RNA and DNA (ribonucleic acid
and deoxyribonucleic acid).
Are structural elements in the cell walls of bacteria (peptidoglycan or
murein), plants (cellulose) and animals (chitin).
They are linked to many proteins and lipids. Such linked carbohydrates
are important in cell-cell communication and in interactions between cells
and other elements in the cellular environment.
As “food” for energy supply (starch, glycogen, dextran’s) and production of
fats.
TYPES:
- MONOSACCHARIDES
Monosaccharides (C-H2O)n, n > 3, are the simplest form of
carbohydrates.
They may be subcategorized as aldoses or ketoses, if the molecule
contains an aldehyde or ketone functional group respectively.
Aldoses have a carbonyl group in the form of an aldehyde on the end of
the carbon chain and ketoses have a ketone group somewhere along the
sugar backbone.
Examples of monosaccharides: Glucose,Fructose,Galactose,Ribose
2.DISACCHARIDES
Disaccharides, or chemical formula of Cn(H2O)n-1, n > 5, are
namely two monosaccharides linked by condensation or
dehydration synthesis.
As a result, a glyosidic bond is formed when the -OH of one sugar
molecule joins with that of another sugar molecule.
The glyosidic bond can be broken by hydrolysis, which is the
addition of the water molecule, to form two monosaccharides.
Examples of disaccharides:lactose,maltose,sucrose
3.POLYSACCHARIDES
Polysaccharides (also called Glycans), the chemical
formula is written as Cn(H2O)n-1, for which 200 < n < 2500,
or (C6H10O5)n, 40<n<3000, are polymers or multiple units
of monosaccharides.
They are constructed by glyosidic bonds and make ideal
storage products due to their structure and solubility.
Examples of polysaccharides: cellulose,starch,glycogen
4.OLIGOSACCHARIDES
Oligosaccharide is a carbohydrate polymers comprise
three to ten monosaccharides, or, simple sugars.
They were linked together mostly by O-glycosidic bond
through condensation reaction between an anomeric
carbon of a monosaccharide and the other.
Example of oligosaccharides are: glucose,fructose which
are bonded together.
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