Genes exhibit independent assortment but do not act independently in their phenotypic expression.

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Only fully methylated origins can initiate replication;

hemimethylated daughter origins cannot be used again until they have been restored to the fully methylated state.

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The GATC sites AT THE ORIGIN remain hemimethylated for 13 minutes after replication called as refractory period of replication cycle or delay time.

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At typical GATC sites elsewhere in the genome, remethylation begins immediately (1.5 minutes) following replication.

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One other region behaves like oriC:

The promoter of the dnaA gene also shows a delay before remethylation begins.

While it is hemimethylated, the dnaA promoter is repressed, which causes a reduction in the level of DnaA protein.

So Initiation of Replication (E.coli) takes place when GATC at origin is full methylated as well as promoter of DnaA gene. 

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An unmethylated CG site remains unmethylated after replication.

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#Unit 3. Fundamental Processes

DnaA is the E. coli licensing factor that must be made anew for each round of replication. Drugs that block protein synthesis block a new round of replication, but not continuation of replication.