Both RNA and DNA are nucleic acids, and both are composed of nucleotides. The nucleotides are namely: Adenine, guanine, cytosine, thymine, and uracil. Adenine is always paired with thymine or uracil; guanine is always paired with cytosine. RNA contains the nitrogenous base uracil rather than thymine. DNA contains the nitrogenous base thymine rather than uracil.
