sentences: dna is a kind of nucleic acid
docs: dna_molecule is nucleic_acid_molecule. dna_polymerase is nucleic_acid_polymerase. nucleic_acid is macromolecule. nucleic_acid_molecule is nucleic_acid_molecule. nucleic_acid_molecule is polymer. nucleic_acid_molecule is polynucleotide. dna_denaturation is nucleic_acid_denaturation. nucleic_acid is chemical_substance. rna_molecule is nucleic_acid_molecule.