The purine or pyrimidine base was removed from thelabeled nucleotide base.
A DNA polymerase enzyme recognizes this and replaces the is inserted nucleotide allowing replication to continue. Calibration corrects approximately 99% of these types of errors but is still not sufficient for normal cellular function. Topoisomerases act in the region before the replication fork and prevent supercoiling.
Primase synthesizes RNA primers complementary to the DNA strand. Cells have various mechanisms to prevent mutations and permanent changes in DNA sequences. During DNA synthesis, most DNA polymerases check their work by repairing most mismatched bases in a process called proofreading. Errors can occur during the process of DNA replication. Nucleotide bases can be is inserted, deleted, or mismatched in a DNA strand.
