Here's why:

* Proteins: Proteins are made up of amino acids, and each amino acid contains a nitrogen-containing amino group (-NH2). This nitrogen is essential for the structure and function of proteins.

* Nucleic Acids: Nucleic acids (DNA and RNA) are made up of nucleotides. Each nucleotide contains a nitrogenous base (adenine, guanine, cytosine, thymine, or uracil), a sugar, and a phosphate group. The nitrogenous bases are the key components that store and transmit genetic information.

Therefore, nitrogen is a vital element for both proteins and nucleic acids, playing a crucial role in their structure, function, and the ability to store and transmit genetic information.