Functions
of Carbohydrates
Carbohydrates
are the main sources of energy in the body. Brain cells and RBCs
are almost wholly dependent on carbohydrates as the energy source. 2) Storage
form of energy (starch and glycogen). 3) Excess
carbohydrate is converted to fat. 4) Glycoproteins
and glycolipids are components of cell membranes and receptors. 5) Structural
basis of many organisms: Cellulose of plants; exoskeleton of
insects, cell wall of microorganisms, mucopolysaccharides as ground
substance in higher organisms. The
general molecular formula of carbohydrate is Cn(H2O)n.
For example, glucose has the molecular formula C6H12O6.
Carbohydrates are polyhydroxy aldehydes or ketones or compounds
which yield these on hydrolysis.
NOMENCLATURE:
Molecules
having only one actual or potential sugar group are called
monosaccharides. They cannot be further hydrolysed into smaller
units. When two monosaccharides are combined together with
elimination of a water molecule, it is called a disaccharide.
Trisaccharides contain three sugar groups. Further addition of sugar
groups will correspondingly produce tetrasaccharides,
pentasaccharides and so on, commonly known as oligosaccharides. When
more than 10 sugar units are combined, they are generally named as
polysaccharides. Polysaccharides having only one type of
monosaccharide units are called homopolysaccharides and those having
different monosaccharide units are heteropolysaccharides. Sugars
having aldehyde group are called aldoses and sugars with keto group
are ketoses. Depending on the number of carbon atoms, the
monosaccharides are named as triose (C3), tetrose (C4), pentose (C5),
hexose (C6), heptose (C7) and so on.
STEREOISOMERS:
Compounds having same structural formula, but differing in spatial
configuration are known as stereoisomers. While writing the
molecular formula of monosaccharides, the spatial arrangements of -H
and -OH groups are important, since they contain asymmetric carbon
atoms. Asymmetric carbon means that four different groups are
attached to the same carbon. The reference molecule is
glyceraldehyde (glycerose) which has a single asymmetric carbon atom.
RELATED;
2. BIOCHEMISTRY
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