Mismatch Repair

This animation shows how mistakes made during DNA replication are repaired by the cell.

Replication mistakes may occur as DNA polymerase copies the DNA strands. One type of mistake, called a mismatch, happens when the polymerase incorporates the wrong nucleotide into a strand. The animation illustrates how mismatches can be fixed with a set of repair proteins. These proteins recruit an enzyme called EXO1 to remove the incorrect section. DNA polymerase then replaces the removed section with the correct nucleotides.

This animation is a clip from a 2003 Holiday Lecture Series, Learning From Patients: The Science of Medicine. Depending on students’ background, it may be helpful to pause the animation at various points to discuss different structures or proteins.