Why are DNA and RNA called nucleic acids?
It’s true that nucleotides are composed of both acidic and basic subunits. When examined individually, one could argue that a nucleotide is both an acid and a base. However, when examining polynucleotides, particularly in the case of DNA, the acidic character of the phosphate group is significantly more pronounced than any basic contribution of the bases. When looking at the structure of DNA and RNA, the acidic phosphate groups along the backbone of the strands are more exposed to the environment than the bases (this is especially true in DNA, where any potential basic reactivity is diminished through hydrogen bonding with the complimentary strand). The bases in RNA are also very often H-bonded to other bases along the same strand, thus diminishing the basic reactivity. Additionally, the bases along the strand in DNA interact as they stack (a major stabilizing force in DNA). This base stacking interaction also decreases their ability to act as bases. In essence, the phosphate groups in