関連ワード:  what is basic nitrogen    what is nitrogenous base    what is nitrogenous base in dna    what is nitrogenous base in biology    what is nitrogen base simple definition    what is nitrogenous base pair    what is nitrogenous base definition    what is nitrogenous base pair of dna    what is nitrogenous base in rna    what is nitrogenous base found in dna