The purpose of this study is to analyze variations in how the gene concept is used and conceived in different sub-disciplines in biology. An examination of the development of subject matter and the use of the gene concept in a common college biology textbook shows that the gene concept is far from presented in a consistent way. The study describes and categorizes five different gene concepts used in the textbook; the gene as a trait, an information-structure, an actor, a regulator and a marker. These conceptual differences are not dealt with in an explicit manner. This constitutes one of the sources for confusion when learning about genes and genetics.