Dear Dr. Gene E. Tics:

I have been testing your Unidirectional and Single Fork Hypotheses and based on my results, I have come to the following conclusions:

Replication of the E. coli chromosome begins at a specific site called the origin. But instead of one replication fork moving away from the origin, two replication forks move in opposite directions away from the origin. Because the chromosome is a closed loop, the two forks will eventually meet when replication is finished. Replication will be terminated and the two copies will separate. This is called Bidirectional Replication and I have animated this procedure so that you might understand it better.

Bidirectional Replication

E. coli is also capable of initiating multiple replication forks at the origin so that a new pair of forks can begin replication of the chromosome before the previous pair end. In this sense, the rate replication can match the rate of cell division. I have also animated this procedure.

Multiple Replication Forks

Dr. Gene E. Tics received your letter and thanks you for pointing out the errors in his work. For all your achievements you have been awarded with the Microbiology Medal Of The Year....Congratulations!