Carbohydrates
- It is the main source of energy in human
body that is glucose as the energy source.
- It is widely distributed to animal and
plant tissues.
- Most of the carbohydrates have carbon,
hydrogen, and oxygen, some carbohydrates have nitrogen, sulphur, and phosphate.
- Carbohydrates is defined as polyhydroxy
aldehydes or ketones or compounds which yield the derivative on hydrolysis.
- It is classified in to four types, they
are Monosaccharides, Disaccharides, Oligosaccharides, and polysaccharides.
Types of carbohydrates
Monosaccharides
- It is simple sugar, with one actual or
potential sugar group.
- It is easily soluble in water.
- It has low molecular weight.
- It tastes as sweet in nature.
- It cannot be further hydrolysed in to
smaller units.
- It is classified in to two types, they are
o
Aldoses (Examples: Glutaraldehyde, Ribose,
Glucose, etc.)
o
Ketoses (Examples: Dihydroxyacetone,
Ribulose, Fructose)
Disaccharides
- It is made up of two monosaccharide units.
- The two units were linked by glycosidic bonds.
- It is classified in to two types, they are,
o
Reducing disaccharides (Examples: Maltose,
Lactose)
o
Non-Reducing disaccharides (Example:
Sucrose)
Oligosaccharides
- It is made up of three to ten monosaccharide
units.
- Do not occur as free entities.
- It is occurred as glycoconjugates (Glycoprotein,
Glycolipids).
- Some examples of the oligosaccharides are
mentioned below,
o
Raffinose (present in beans, cabbage, and
broccoli)
o
Stachyose (present in vegetables and plant
o
Verbacose (present in legumes).
Polysaccharides
- It is made up of more than ten
monosaccharide units.
- It has high molecular weight.
- It is partially dissolved in water.
- It tastes not as sweet.
- It is classified in to two types, they are
mentioned below,
o
Homoglycans (Examples: Starch, Dextrin,
Glycogen, Cellulose, Inulin, Dextran, and Chitin).
o
Heteroglycans (Examples: Agar, Agarose,
Gum, Pectin, and Glycosaminoglycans)
Functions of Carbohydrates
- It is most abundant dietary source of
energy
- In the form of Glycogen, it is stored in
liver and muscle.
- Some non-digestible carbohydrates are
cellulose, agar, gum and pectin, which was served as dietary fibers.
- Some carbohydrates act as precursors of
organic compounds like Ribose, deoxyribose (DNA and RNA), Glycolipids, Glycoproteins,
and Proteoglycans.
- Participate in the structure of cell membrane.
- It plays a role in lubrication in joints,
cellular intercommunication, and immunity.
- Some carbohydrates act as structural
component, they are
o
Glycosaminoglycans in human
o
Cellulose in plants
o
Chitin in insects.
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