A large team of enzymes and other proteins carries out DNA replication. It takes E. coli less than an hour to copy each of the 4.6 million base pairs in its single chromosome and divide to form two identical daughter cells. A human cell can copy its 6 billion base pairs and divide into daughter cells in only a few hours. This process is remarkably accurate, with only one error per 10 billion nucleotides. More than a dozen enzymes and other proteins participate in DNA replication. Much more is known about replication in bacteria than in eukaryotes. o The process appears to be fundamentally similar for prokaryotes and eukaryotes. The replication of a DNA molecule begins at special sites called origins of replication. In bacteria, this site is a specific sequence of nucleotides that is recognized by the replication enzymes. o These enzymes separate the strands, forming a replication “bubble.” o Replication proceeds in both directions until the entire molecule is copied. In eukaryotes, there may be hundreds or thousands of origin sites per chromosome.
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