Final answer:
The common element of life that is not found in proteins is phosphorus.
Step-by-step explanation:
Proteins are macromolecules that play crucial roles in various biological processes. They are composed of amino acids, which are organic compounds containing carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and sometimes sulfur (S). Therefore, all the elements mentioned in the question, including carbon, hydrogen, oxygen, nitrogen, and sulfur, can be found in proteins.
The correct answer to the question is phosphorus (P). Phosphorus is not a common element found in proteins. It is an essential element for life but is primarily found in nucleic acids (such as DNA and RNA) and other molecules like ATP (adenosine triphosphate).
For example, nucleotide monomers, the building blocks of nucleic acids, contain a sugar, a phosphate group (containing phosphorus), and a nitrogenous base. In contrast, amino acid monomers, the building blocks of proteins, do not contain phosphorus.
Learn more about Element not found in proteins