<P> Nucleotides are organic molecules that serve as the monomer units for forming the nucleic acid polymers deoxyribonucleic acid ( DNA ) and ribonucleic acid ( RNA ) , both of which are essential biomolecules in all life - forms on Earth . Nucleotides are the building blocks of nucleic acids ; they are composed of three subunit molecules : a nitrogenous base , a five - carbon sugar ( ribose or deoxyribose ) , and at least one phosphate group . They are also known as phosphate nucleotides . </P>
what are the monomer building blocks of dna and rna
Nucleotides