Carbohydrates- Chemical Composition and Biological Significance


Carbohydrates are compounds of carbon, hydrogen, and oxygen. They are also called ‘hydrates of carbon’ because in them hydrogen and oxygen occur in a ratio of 2:1, similar to that found in water. They are also called saccharides because they are sugars or polymers of sugars or monosaccharides. Examples are glucose, fructose, sugar, starch, glycogen, cellulose, etc.

Carbohydrates are the basic components of food. They are the principal source of energy for all living beings. 1g mol of carbohydrates yield 4.9 kcal energy.

Chemical Composition of Carbohydrates:

Chemical Composition of Carbohydrates

Biological Significance of Carbohydrates:

(1) Major Source of Energy- Carbohydrates are the main source of energy for living cells. They are used as respiratory fuel. In the presence of oxygen, they decompose into CO2 and water and liberate energy to be utilized by body cells.

(2) Structural Components- In plant cells carbohydrates (cellulose) constitute the structural framework. In animal cells, these form a protective fuzzy coat on the surface of cells.

(3) Storage- Carbohydrates are stored in the body as an immediate source of energy. The stored carbohydrate is starch in plants and glycogen in animals.

(4) Role in Metabolism- Carbohydrates play a key role in the metabolism of amino acids and fatty acids.

(5) Special Functions:

  • Some glycoproteins act as hormones.
  • Glycoproteins on the cell surface help in cell recognition and help in the immune system of the body.
  • Heparin, a mucopolysaccharide acts as an anticoagulant.

Plant and Animal Cell
Difference between DNA and RNA
Mitosis: Process and Significance
DNA Fingerprinting
Meiosis: Process and Significance
Human Genome Project
Modes of Nutrition
Chromosomal Theory Of Inheritance
Alimentary Canal of Man or Digestive Tract
Human Genetic Disorders
Tissues and other Level of Organization-NIOS

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