Here's why:

* DNA is made of nucleotides: It's composed of building blocks called nucleotides, which consist of a sugar (deoxyribose), a phosphate group, and a nitrogenous base (adenine, guanine, cytosine, or thymine).

* Proteins are made of amino acids: Proteins are long chains of amino acids linked together.

* Different functions: DNA stores genetic information, while proteins perform a wide variety of functions, including structural support, enzymatic activity, and signaling.

While DNA does not replicate itself directly, it does contain the instructions for its own replication. This process is carried out by enzymes, which are proteins. So, while DNA is not a protein, proteins are essential for DNA replication.