Download Building blocks of nucleic acids

Building blocks of nucleic acids (nucleotides)
A nucleotide is the basic building block of nucleic acids (RNA and DNA). A nucleotide consists of
:
(a) A pentode (5-carbon) sugar molecule (either ribose in RNA or deoxyribose in DNA)
attached to a
(b) phosphate group and a
(c) nitrogen-containing base.
The bases used in DNA are adenine (A), cytosine (C), guanine (G) and thymine (T). In RNA, the
base uracil (U) takes the place of thymine. DNA and RNA molecules are polymers made up of
long chains of nucleotides.
The pentose sugar in DNA (2′-deoxyribose) differs from the sugar in RNA
(ribose) by the absence of a hydroxyl group (―OH) on the 2′ carbon of the sugar
ring. A and G are categorized as purines, and C, T, and U are collectively
called pyrimidines. The phosphate group connects successive sugar residues by bridging
the 5′-hydroxyl group on one sugar to the 3′-hydroxyl group of the next sugar in the
chain. Without an attached phosphate group, the sugar attached to one of the
bases is known as a nucleoside. These nucleoside linkages are called phosphodiester
bonds and are the same in RNA and DNA.

Nucleotides 5’& 3’ phosphodiester linkages