The building blocks of DNA are nucleotides. Each nucleotide consists of three parts:

1. A sugar molecule: Deoxyribose

2. A phosphate group: This is a negatively charged molecule that links nucleotides together.

3. A nitrogenous base: There are four different nitrogenous bases in DNA:

* Adenine (A)

* Guanine (G)

* Cytosine (C)

* Thymine (T)

These nucleotides join together to form long chains, with the phosphate group of one nucleotide linking to the sugar of the next. The sequence of these nucleotides determines the genetic information encoded in the DNA molecule.