With these safeguards, their error rates are typically very low and range from one in a million bases to one in a billion bases. As noted in chapter 9, DNA polymerases are highly processive enzymes that contain proofreading and editing functions.
For example, DNA mutations can be caused by mistakes made by the DNA polymerase during replication. They can be large scale, altering the structure of the chromosomes, or small scale where they only alter a few or even a single base or nucleotide. Mutations are random changes that occur within the sequence of bases in DNA.
