Structures of Nucleic Acids

Abstract

What is the chemical structure of a deoxyribonucleic acid (DNA) molecule? DNA is a polymer of deoxyribonucleotides. All nucleic acids consist of nucleotides as building units. A nucleotide has three components: sugar, base, and a phosphate group. (The combination of a sugar and a base is a nucleoside.) In the case of DNA, the nucleotide is known as deoxyribonucleotide, because the sugar in this case is deoxyribose. The base is either a purine (adenosine or guanine) or a pyrimidine (thymine or cytosine) (Fig. 2.1). Another type of nucleic acid is ribonucleic acid (RNA), a polymer of ribonucleotides also consisting of three components - a sugar, a base and a phosphate, except that the sugar in this case is a ribose, and that the base thymine is replaced by uracil.