Final answer:
DNA is made up of monomers called nucleotides, which consist of three parts: a nitrogenous base, a pentose sugar, and a phosphate group. There are two types of nitrogenous bases, purines (adenine and guanine) and pyrimidines (cytosine and thymine), which pair to form DNA's structure.
Step-by-step explanation:
The building blocks (monomers) of DNA are known as nucleotides. Each nucleotide can be broken down into three parts: a nitrogenous base, a pentose (five-carbon) sugar, and a phosphate group. These three parts are essential for the nucleotide structure, with each nitrogenous base in a nucleotide being attached to the sugar molecule, which in turn is attached to one or more phosphate groups.
The nitrogenous bases in DNA are of two types: purines and pyrimidines. Purines include adenine (A) and guanine (G), which have a double-ringed structure, while pyrimidines include cytosine (C) and thymine (T), which have a single-ringed structure. These bases pair specifically (A with T and G with C) to form the steps of the DNA double helix.