Science teachers are considered to be one of the most influential factors for effective science learning. According to Shulman (1986) content knowledge and pedagogical knowledge by themselves are not sufficient to teach science concepts effectively. Accordingly, Shulman proposed another knowledge type called “pedagogical content knowledge” (PCK) in which content knowledge is transformed by teacher in order to make science concepts meaningful for students’ understanding.

Because of cell diviison topics are most difficult science concepts to be taught and learnt, and cell division topics were selected to be studied based on topic specific nature of PCK. In other word, This study examined in-service science teachers' PCK in mitosis and meiosis topics. 

Magnusson et al. (1999) PCK model was used in this PCK. All components of the model and their sub-components were used in current study. First component is orientation towards science that is related with teacher beliefs about science, science teaching and science learning. Orientation towards science shapes other PCK components and it is hierarchically superior to other components. Second component is knowledge of curriculum. Knowledge of curriculum includes two sub-components which are knowledge of goals and objectives and knowledge of materials. Third component is knowledge of learner. This component includes two sub-components which are teacher understanding of students' requirements for learning science and student difficulties to understand science content including students' misconceptions. Another component of the PCK is knowledge of assessment. This component includes dimension of science learning to assess and methods of assessing science learning. Dimension of science learning refers to what teachers assess, and methods of assessing science learning refer to how and when teachers assess their students. The last component of the PCK is knowledge of instructional strategy. Knowledge of instructional strategy includes two sub-components which are subject-specific strategies and topic-specific strategies. Subject specific strategies are parallel with orientation towards science and it is not topic specific. On the other hand, topic specific strategies are unique to topics. Topic specific strategies include knowledge of representations and knowledge of activities. Although PCK is comprised of its components, it is more than total of its components. Therefore, not only PCK components should be studied, but also the relationship between its components should be studied to better understand teachers' PCK which is thought and suggested as a solution for teaching related problems. The more researchers understand teachers' PCK, the more they assist the development of quality of science teaching. 

Grossman, P. L. (1990). The making of a teacher: Teacher knowledge and teacher education. New York: Teachers College Press. Magnusson, S.J., Borko, H., & Krajcik, J.S. (1999). Nature, source, and development of pedagogical content knowledge for science teaching. In J. Gess- Newsome & N. Lederman (Eds.), Examining Pedagogical content Knowledge (pp.95-132). Boston, MA: Kluwer Press. Merriam, S.B. (2009). Qualitative research: A guide to design and implementation. San Francisco, CA: Jossey-Bass. Shulman, L.S. (1986).Those who understand: Knowledge growth in teaching. Educational Researcher, 15(4), 4-13. Shulman, L. (1987) Knowledge and Teaching: Foundations of the New Reform Harvard Educational Review, 57(1): 1- 22 Veal, W.R. & Makınster, J.G. (1998). Pedagogical content knowledge taxonomies Electronic Journal of Science Education available at http://unr.edu/homepage/crowther/ejse/vealmak.html (accessed 31.01.2014) Abell, S.K. (2008). Twenty years later: Does pedagogical content knowledge remain a useful idea? International Journal of Science Education, 30(10), 1405-1416. Abell, S.K., Rogers, M.A.P., Hanuscin, D.L., Lee, M.H., & Gagnon, M.J. (2009). Preparing the next generation of science teacher educators: A model for developing PCK for teaching science teachers. Journal of Science Teacher Education, 20, 77-93.