Biology that is a branch of science examining organisms in every aspect has a very wide content. Besides this wide content, there are abstract concepts in some subjects. Various alternative conceptions are determined in different education levels especially in abstract and microscopic biology subjects. The aim of this study is to determine the alternative conceptions of pre-service teachers related with the genetic material in gametes and somatic cells. 97 pre-service teachers that are freshmen at university participated in the research. In order to determine the alternative conceptions about the subject, open-ended questions are asked to the pre-service teachers. Also, 12 pre-service teachers amongst 97 pre-service teachers are selected for semi-structured interviews and interviews are performed. Analysing the data obtained from the open-ended questions and interviews, it is determined that pre-service teachers have many alternative conceptions about the genetic materials in gametes and somatic cells. These alternative conceptions are introduced in categories and discussed.