Sulfur-containing amino acids are essential building blocks of proteins that include sulfur in their structure. The two primary sulfur-containing amino acids are cysteine and methionine. These amino acids play crucial roles in various biological processes, including protein synthesis and the formation of important molecules like glutathione, which helps protect cells from damage. Cysteine is unique because it can form disulfide bonds, which stabilize protein structures. Methionine, on the other hand, is often the first amino acid in protein chains and is vital for initiating protein synthesis. Both amino acids contribute to overall health and are found in various foods, including meat, eggs, and legumes.