DNA160-page11 - DNA polymerase sliding rings. To do so, the...

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DNA: Structure and Replication - 11 DNA replication is continuous along the leading strand of the original template DNA molecule, because the newly synthesized daughter nucleotides can follow the path of DNA helicase. However, the lagging template strand of DNA is unzipped in the 5' to 3" direction so new DNA synthesis must be discontinuous. Its rate of synthesis lags behind that of the leading strand. Additional DNA polymerase enzymes must be attached at unzipped regions, but the synthesis direction of the lagging strand is opposite the direction of the unzipping DNA helicase enzyme. Since DNA polymerase must do both sides, the lagging strand has to be folded back on itself to "face" the correct 5' to 3' direction to fit into the
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Unformatted text preview: DNA polymerase sliding rings. To do so, the lagging strand must be unwound a greater distance before replication can start, and will be looped to provide the needed orientation for DNA polymerase. New DNA polymerase enzyme molecules have to attach and work on small portions of the lagging strand of the unzipped DNA molecule. Once segments of the lagging strand, called Okazaki fragments, are synthesized, the RNA primer nucleotides are removed and DNA polymerase replaces them with DNA nucleotides. The enzyme, DNA ligase, links the short pieces of the lagging side together. Note: Each Okazaki fragment must be initiated by a RNA primer....
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