DNA mismatches and their repair. (A) If uncorrected, the mismatch will lead to a permanent mutation in
one of the two DNA molecules produced by the next round of DNA replication. (B) If the mismatch is "repaired" using the newly synthesised DNA strand as the template, both DNA molecules produced by the next round of DNA replication will contain a mutation. (C) If the mismatch is corrected using the original template (old) strand as the template, the possibility of a mutation is eliminated. The scheme shown in (C) is used by cells to repair mismatches, as shown in the next figure.