The element found primarily in proteins is nitrogen (N). Nitrogen is a crucial component of amino acids, which are the building blocks of proteins. It provides the backbone structure and functional groups that determine the properties and interactions of proteins.

In nucleic acids, the primary element is phosphorus (P). Phosphorus is a vital part of the nucleotide subunits that make up nucleic acids, such as DNA and RNA. It forms the backbone structure and interacts with other molecules to facilitate genetic information storage and transmission.