ISSA Nutritionist Exam 2025 – 400 Free Practice Questions to Pass the Exam

Sulfur is a critical component of the amino acids cysteine and methionine. These two amino acids contain sulfur in their structures, which plays vital roles in various physiological processes. For example, cysteine is important for protein synthesis, enzyme function, and the formation of antioxidant molecules like glutathione. Methionine serves as a precursor for cysteine and is also essential for initiating protein synthesis due to its role as the first amino acid in the polypeptide chain.

The presence of sulfur in these amino acids is crucial not only for the structural properties of proteins but also for the regulation of metabolic pathways and detoxification processes in the body. Therefore, cysteine and methionine are recognized as the amino acids that directly associate with sulfur, making this combination the correct choice.

In contrast, other amino acids listed do not contain sulfur in their structures, and while they may have their own functions and roles within the body, they do not contribute to sulfur's presence in amino acid metabolism.