2.1 The Structure of Nucleic Acids
Nucleic acids are long polymers of repeating subunits called nucleotides. Each nucleotide consists of three components: a five-carbon sugar (ribose in RNA and deoxyribose in DNA); a phosphate (—PO4) group; and an organic nitrogen containing base.
When a nucleic acid polymer forms, the phosphate group of one nucleotide binds to the hydroxyl group of another, releasing water and forming a phosphodiester bond. A nucleic acid, then, is simply a chain of five-carbon sugars linked together by phosphodiester bonds with an organic base protruding from each sugar.