Genes are not made of a single chemical. They are made of deoxyribonucleic acid (DNA), which is a long, complex molecule composed of four different nucleotides:

* Adenine (A)

* Guanine (G)

* Cytosine (C)

* Thymine (T)

These nucleotides are arranged in a specific sequence, and this sequence determines the genetic information encoded by the gene.

So, while DNA is the primary chemical component of a gene, it's not a single chemical. It's a complex structure made of multiple molecules.