Nucleosides: Nucleoside contains only two basic components of nucleic acids (a pentose sugar and a nitrogenous base). During their formation, 1- position of pyrimidine or 9 – position of purine moiety is linked to C1 of sugar (ribose or deoxyribose) by b – linkage.
General structure of a nucleoside
Depending upon the type of sugar present, nucleosides are of two types:
(i) Ribonucleosides and
Nucleotides: Nucleotides contains all the three basic components of nucleic acids. Nucleotides are nucleoside monophosphates.
They are of two types depending upon the type of sugar – Ribonucleotides and Deoxyribonucleotides. Nucleotide may be represented as follows.
|1.||Sugar present in DNA is 2-deoxyribose.||1.||Sugar is D-ribose.|
|2.||It contains cytosine and thymine as pyrimidine.||2.||It contains cytosine and uracil as pyrimidine.|
|3.||It has double stranded a – helix structure.||3.||It has single stranded a – helix.|
|4.||DNA occurs in the nucleus of cell.||4.||RNA occurs in cytoplasm of the cell.|
|5.||Controls transmission of hereditary material.||5.||It control the synthesis of proteins.|
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