DNA Structure and Replication

ID #1117

How does the DNA polymerase complex know how long to make the Okazaki fragment?

The length of an Okazaki fragment is ultimately determined by the spacing of the primers. Primase is on a mechanical lever, kind of like the tonearm of a record player. It "sits" down on the template just long enough to lay in roughly 10 bases, then is physically swung away from the template. This cycle repeats about once per second. And since E. coli DNA polymerase III can synthesize about 1000 bases per second, this ends up producing Okazaki fragments in E. coli that are about 1000 bases in length.

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