In prokaryotes, up to 500 nucleotides are added per second. It takes only a few hours to copy the 6 billion bases of a single human cell. Only about one in 1 to 10 billion nucleotides is incorrectly paired. Generally similar in prokaryotes and eukaryotes. Specific proteins required to initiate replication bind to each origin.
Eukaryotic chromosomes have hundreds or thousands of replication origins.
The many replication bubbles formed by this process, eventually merge forming two continuous DNA molecules. The Y-shaped regions of replicating DNA molecules where new strands are growing. Elongating a new DNA strand Enzymes called DNA polymerases catalyze synthesis of a new DNA strand. According to base-pairing rules, new nucleotides align themselves along the templates of the old DNA strands. DNA polymerase links the nucleotides to the growing strand.