Page 17 - Lesson Notes - Biomolecules 1

The backbone of DNA is formed by the sugar phosphate-sugar chain. The nitrogen
bases are projected more or less perpendicular to the backbone of DNA and faces
inside. A and G of one strand base pairs with T and C respectively on the other
strand.
Between A and T (A== T), there are two hydrogen bonds while, there are three
hydrogen bonds between G and C(G=C).
DNA has a uniform thickness of 20 A and pitch of is 34 nm. Thus, one turn of DNA
measures 3.4 nm (rise per base pair) and consists of 10 nucleotides (or ten base
pairs). This form of DNA is called B-DNA.
Functions of Nucleic Acids
Nucleic acidplays multiple role in living organism these are given as follows
(i) It enables cell to grow, maintain and divide by directing the synthesis of structural
proteins.
(ii) Acts as a genetic material, i.e., transfer hereditary characters from one generation
to the next.
Differences between DNA and RNA are given below