Topic overview

Start with the big picture

Amino acid properties begin with the R group: it influences polarity, charge, and functional role. Classifications include nonpolar, polar uncharged, acidic, basic, and aromatic groups, as well as essential and semi-essential nutritional categories. Functional subsets such as sulfur-containing, hydroxyl-containing, and imino amino acids highlight additional distinctions. The lesson also introduces amphoteric behavior, zwitterions, pKa, and isoelectric point, explaining how these concepts relate to ionization and solubility. Structural features have practical consequences: cysteine can form disulfide bridges, proline constrains the protein backbone, and aromatic residues absorb ultraviolet light. Finally, the topic connects side-chain chemistry to peptide bonds and post-translational modifications.