Biology majors have difficulty applying their chemistry knowledge to research topics in biology. Here we describe a problem-based laboratory activity that requires biology majors taking microbiology to apply their knowledge of organic chemistry and to collaborate with organic chemistry lab students to study p-aminobenzoic acid (PABA) derivatives. The organic chemistry students synthesize and characterize an array of novel PABA derivatives using the Fischer esterification reaction. They present their derivatives to the microbiology class and both classes predict which derivative would make the best UV light blocker. The microbiology students complete an experiment to test which derivative acts as the best UV light blocker.