FIGURE 2.20 Replication of DNA at a replication fork in bacteria is denatured, DNA helicase unwinds the DNA strands in front of the replication fork, and single-strand binding protein bind to the single strands and keep them denatured. One strand serves as template for discontinuous synthesis of the lagging strands and continuous DNA synthesis of the leading strand. Replication of the DNA strands proceeds in the opposite direction with leading strand replication moving in the direction of the fork. Primase adds short RNA primers to the lagging strand to prime replication, and ligase produces a continuous DNA strand from discontinuous replication.