The sequence of purines and pyrimidines in nucleic acids and polynucleotides. Included here are nucleotide-rich regions, conserved sequence, and DNA transforming region.

• 核酸及多核苷酸中的嘌呤或嘧啶序列；包括富含核苷区；保存序列及脱氧核糖核酸转换区.