This directed case study walks students through an examination of normal protein structure so that they can recognize the role of amino acids and different types of bonds to form the four levels of protein structure and to help them diagnose what happens when there is a mutation that results in a change in the protein structure. The case centers around a student learning about a voltage-gated ion channel that has been found to cause epilepsy when certain mutations exist. Before beginning the case study, students should receive a short lecture about proteins and read the corresponding book chapter talking about proteins when introducing macromolecules to introductory biology students. Then, students are asked to work through the case in small groups. The case covers the four levels of protein structure, the three classes of amino acid side chains, the types of bonds that form the levels of protein structure, and how changes of even a single amino acid can change protein structure and function.