What elements do amino acids contain in addition to carbon, hydrogen, and oxygen?

Amino acids are the building blocks of proteins, and they have a specific structure that distinguishes them from other organic molecules. In addition to carbon, hydrogen, and oxygen, amino acids contain nitrogen, which is a fundamental component of their structure. This is because every amino acid has an amine group (-NH2), which includes nitrogen as a key element.

Some amino acids also contain sulfur, specifically those with sulfur-containing side chains, such as cysteine and methionine. The presence of nitrogen is critical for forming peptides and proteins, which are essential for various biological functions, including enzyme activity, cellular structure, and signaling.

The other options refer to elements that do not play a fundamental role in the structure of amino acids. Iron, sodium, calcium, potassium, magnesium, and fluorine do not form part of the basic amino acid structure and are not universally present in all amino acids. Thus, the answer emphasizes the unique inclusion of nitrogen, and occasionally sulfur, as key components beyond carbon, hydrogen, and oxygen.