Here are the essential concepts you must grasp in order to answer the question correctly.
Amino Acids
Amino acids are organic compounds that serve as the building blocks of proteins. Each amino acid consists of a central carbon atom, an amino group, a carboxyl group, a hydrogen atom, and a variable side chain (R group) that determines its properties. There are 20 standard amino acids, categorized into polar, nonpolar, acidic, and basic groups based on their side chains.
Recommended video:
Amino Acid Catabolism: Amino Group Example 2
Nonpolar Amino Acids
Nonpolar amino acids have side chains that are hydrophobic, meaning they do not interact well with water. These amino acids tend to cluster together in the interior of proteins, stabilizing their structure through hydrophobic interactions. Examples include alanine, valine, and leucine, but the specific amino acid in the question is cysteine, which contains a sulfur atom in its side chain.
Recommended video:
Nonpolar Amino Acids Concept 1
Cysteine
Cysteine is a nonpolar amino acid characterized by the presence of a thiol (-SH) group in its side chain, which contains sulfur. This unique feature allows cysteine to form disulfide bonds with other cysteine residues, contributing to the stabilization of protein structures. The three-letter abbreviation for cysteine is 'Cys'.
Recommended video:
Interactions within the Tertiary Structure Concept 2