This study explored the nature of the integration of the five components of pedagogical content knowledge (PCK): (a) Orientations toward Teaching Science, (b) Knowledge of Student Understanding, (c) Knowledge of Instructional Strategies and Representations, (d) Knowledge of Science Curriculum, and (e) Knowledge of Assessment of Science Learning. Given the topic and context specificity of PCK, this investigation was conducted in the context of the photosynthesis and heredity instruction of four teachers who were working at the same high school with the same curricular materials. Data sources included classroom observations, semi-structured interviews, lesson plans, instructional materials, and students' work samples. Data were analyzed through three different approaches: (a) in-depth analysis of explicit PCK, (b) enumerative approach, and (c) the constant comparative method. Data analysis indicated five salient features of the integration of the PCK components: (a) the integration of the components was idiosyncratic and topic-specific; (b) Knowledge of Student Understanding and Knowledge of Instructional Strategies and Representations were central in the integration; (c) Knowledge of Science Curriculum and Knowledge of Assessment of Science Learning had most limited connection with other components; (d) Knowledge of Assessment of Science Learning was more often connected with Knowledge of Student Understanding and Knowledge of Instructional Strategies and Representations than with the other components; and (e) Didactic Orientations toward Teaching Science directed Knowledge of Instructional Strategies and Representations inhibiting its connection with other components. This study highlights that the quality of PCK depends on the coherence among the components as well as the strength of individual components. From a methodological perspective, this study demonstrates the possibility to make PCK more visible and accessible by using a PCK Map, a pictorial representation of the interactions of the PCK components. (Contains 3 tables and 3 figures.)