Summary of DNA synthesis in bacteria.

• At the advancing fork, helicase proteins unwind the double helix.

• Primase lays down a short RNA primer.

• Each core enzyme of the DNA polymerase III dimer is bound to a template strand by a beta-subunit sliding clamp.

• Synthesis is continuous on the leading strand, but occurs in Okazaki fragments on the lagging strand.

• The lagging strand loops around to allow concurrent synthesis on both strands.

• DNA polymerase I replaces the RNA primer (synthesized by primase) with DNA.

• DNA ligase joins the Okazaki fragments.