Answer:
nucleotide
Step-by-step explanation:
Nucleotide is the building block of both DNA and RNA composed of a phosphate group, a 5-carbon sugar, and a nitrogenous base. The four nitrogenous bases in DNA are adenine, cytosine, guanine, and thymine while the RNA contains of uracil, instead of thymine, cytosine, guanine and adenine.