The E. coli oriC contains 11 copies of the GATC sequence

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#Unit 3. Fundamental Processes

This is equivalent to nick translation, except that the new DNA replaces a stretch of RNA rather than a segment of DNA.

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#Unit 3. Fundamental Processes

Trombone” model for coordinating replication by two DNA polymerases at the E. coli replication fork

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#Unit 3. Fundamental Processes

Each Okazaki fragment starts with a primer and stops before the next fragment

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#Unit 3. Fundamental Processes

The 5’–3’ exonuclease activity removes the RNA primer while simultaneously replacing it with a DNA sequence extended from the 3’–OH end of the next Okazaki fragment. 

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#Unit 3. Fundamental Processes

To replace the RNA primers with DNA, an enzyme called RNaseH recognizes and removes most of each RNA primer. This enzyme specifically degrades RNA that is base-paired with DNA. RNase H removes all of the RNA primer except the ribonucleotide directly linked to the DNA end.

This is because RNaseH can only cleave bonds between two ribonucleotides. The final ribonucleotide is removed by a 5’ exonuclease that degrades RNA or DNA from their 5’ ends.

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#Unit 3. Fundamental Processes