 What is distinctive about systems biology can in part be understood through the characteristics and implications of different styles of representation. Whereas textbooks and research papers in molecular and cell biology typically contain mechanistic diagrams tracking interactions between specific genes and proteins, representations in systems biology often display interactions between a vast number of molecular components as abstract networks of interconnected nodes and links. This difference in representational style is epistemically significant, because it highlights an increasing focus on the organizational structure of the system as a whole.