What is the basic building block of DNA and RNA?

The basic building blocks of DNA and RNA are nucleotides. Each nucleotide consists of three components: a phosphate group, a five-carbon sugar (deoxyribose in DNA and ribose in RNA), and a nitrogenous base (adenine, thymine, cytosine, and guanine in DNA; adenine, uracil, cytosine, and guanine in RNA). These nucleotides link together to form the long chains that make up the DNA and RNA molecules, which are essential for genetic information storage and transfer.