Nucleic acids allow the transfer of genetic information from generation to generation by means of DNA replication.
There are two types of nucleic acid; 1) DNA
2) RNA, (appears in several forms)
Nucleic acids have 3 main features; 1) Nitrogenous base.
2) 5 Carbon sugar.
3) Phosphate group.
The Nitrogenous group has 4 variants in DNA, these are; Adenine (A)
RNA substitutes Uracil for Thymine.
Adenine is complementary to Thymine and Guanine is complementary the Cytosine. Hydrogen bonds form between complementary bases of different nucleic acids. 2 hydrogen bonds form between A and T and 3 between G and C.
Covalent phosphodiester bonds form between the phosphate groups of neighbouring nucleic acids.
Referneced from: http://biology.about.com/od/molecularbiology/a/nucleicacids.htm