 In purely causal terms, what all these models show is that the sequence of nucleotides in a newly synthesized DNA molecule depends on the sequence of a pre-existing molecule. But the models also contain structural information such as information the DNA double helix topology and the movements undergone by a replicating DNA molecule (still hypothetical at that time). According to the model on the left, the so-called “conservative” model, the two strands of the DNA double helix do not separate prior to replication; they stick together and the daughter molecule grows along an intact double helix that acts as a template as a whole. According to the model in the middle, called the “semi-conservative” mechanism (believed to be correct today), the two strands do separate in the process. The newly synthesized strands grow along the separated pre-existing strands that each acts as templates. On the model on the right, the “dispersive” model, the two strands not only separate in the process, they are also cut into pieces that are then rejoined. While pure causal graphs (i.e., causal graphs that contain only information about what variables depend on what other variables causally) may be used to depict the causes of the separation and cutting events in semi-conservative and dispersive model, it also takes a description of the structure of the DNA molecule, including the topology and relative movements of the strands at different stages of the replication process. This is genuine mechanistic information that must supplement the information contained in the causal graphs in order to provide a normatively adequate mechanistic explanation.