THE MOLECULAR SYNCHRONY AND SEQUENTIAL REPLICATION OF DNA IN ESCHERICHIA COLI

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Abstract
The question of the mechanism of chromosome replication in bacteria has been studied with lysogenic strains of Escherichia coli K-12 Hfr and F- Bacterial growth was synchronized by the frac-tional filtration technique the smaller cells being recovered. One replication cycle of DNA corresponded to a synchronized cell generation. Kinetic studies of prophage duplication over one replication cycle of DNA revealed: first, that the pattern of kinetics is distinctively strain specific; second, that this is brought about only by synchronization; and finally, that the specific time of prophage duplication, expressed in terms of per cent increase of DNA, can be directly correlated with the known genetic linkage map. These findings led to the conclusion that the replication of the chromosome in E. coli K-12 is synchronized and sequential, especially in Hfr, starting from the posterior end where the F factor is attached and proceeding to the forward end.