Topic overview

Start with the big picture

Protein structure begins with amino acids linked into polypeptide chains that fold into specific conformations. Classification by composition distinguishes simple proteins, conjugated proteins with a nonprotein prosthetic group, and derived proteins formed through partial hydrolysis or denaturation. Proteins can also be grouped by shape, solubility, and nutritional value. Their functions span structural support, enzymatic catalysis, transport of substances, hormonal regulation and receptor signaling, immune defense, and contraction or intracellular movement. The lesson also introduces protein composition and physical properties, including denaturation, in which secondary and tertiary structure may be lost while the primary chain remains. These foundations help relate protein categories and properties to their biological roles.