Replication Errors

Sequences of bases are not always matched exactly.An incorrect sequence may be incorporated into the DNA. A change in the base sequence is called a mutation.Mutations are random and spontaneous events. They may also occur due to environmental factors e.g. if a base on the template strand is chemically modified it could lead to the wrong base being incorporated on the new strand or the corresponding base missing on the new strand.Every organism has a fairly consistent mutation rate but there are DNA repair mechanisms and processes by which the cell identifies and corrects the damage to the DNA. If this is not possible the cell undergoes senescence (dormancy) or apoptosis (programmed cell death).There are many events that contribute to replication errors and the misincorporation of DNA nucleotides. There may be insufficient replication factors or nucleotides, breakages due to chemicals or radiation or inaccessibility of the complementary base due to the presence of chemicals called mutagens.