Instructors often present Mendelian genetics and molecular biology separately. As a result, students often fail to connect the two topics in a tangible manner. We have adopted a simple experiment to help link these two important topics in a basic biology course, using red and white onions bought from a local grocery store. A lack of red coloration in white onions is a result of one or more mutations in the color production pathway. This mutation can be seen by the use of polymerase chain reaction (PCR) followed by gel electrophoresis. An absence of an amplified PCR product for one of the genes necessary for color production is associated with a lack of color production--an obvious trait in white onion. The students are able to "see" the difference at the DNA level between the red and white onion.