12.2 Origins can be mapped by autoradiography and electrophoresis UNIDIRECTIONAL REPLICATION Figure 12.5 Different densities of radioactive BIDIRECTIONAL REPLICATION labeling can be used to distinguish unidirectional and bidirectional Heavy density label Light density label replication Not labeled (invisible on autoradiograph) 消当Figure 12.5 Different densities of radioactive labeling can be used to distinguish unidirectional and bidirectional replication. 12.2 Origins can be mapped by autoradiography and electrophoresis