DNA is a complex molecule made up of two long chains of nucleotides twisted into a double helix. Each nucleotide consists of:

* A sugar molecule (deoxyribose)

* A phosphate group

* One of four nitrogenous bases:

* Adenine (A)

* Thymine (T)

* Guanine (G)

* Cytosine (C)

The sequence of these bases along the DNA molecule forms the genetic code, which determines the characteristics of an organism.

While DNA is the primary component of genes, it's important to remember that genes also require other molecules and structures for their function, such as proteins and enzymes.