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Chemical composition of nucleotide

NUCLEIC ACIDS (DNA and RNA)

Introduction


Nucleic acids are important component of cells, which control all the activities of cell.

Chemical composition of nucleotide

Typically a nucleotide is composed of three components i.e.

  • Pentose sugar
  • Nitrogenous base
  • Phosphoric acid
(i) Pentose Sugar
  • Pentose sugar in RNA is ribose(C5H10O5)
  • Pentose sugar in DNA is deoxyribose (C5H10O4)
(ii) Nitrogenous Bases
Nitrogenous bases are of two types:
  1. Single-ringed pyrimidines, which include cytosine (C), thymine (T) and uracil (U).
  2. Double-ringed purines, which include adenine (A) and guanine (G).
(iii) Phosphoric Acid
Phosphoric acid (H3PO4) has the ability to develop ester linkage with OH group of pentose sugar.
In a typical nucleotide, the nitrogenous base is attached to position 1 of pentose sugar while phosphoric acid is attached to position 3 of pentose sugar in front and position 5 of pentose sugar behind it. Since phosphate forms a double ester linkage with pentose sugar, the linkage is known as phosphodiester linkage.

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