The Molecular Stapler

Every day, the DNA inside each of your cells sustains tens of thousands of breaks — from ultraviolet light, metabolic stress, even the ordinary work of copying genetic code. Left unrepaired, this damage would spiral into mutation and death. But the body doesn't discard broken cells. It sends repair. In 2015, biochemist Paul Modrich received the Nobel Prize in Chemistry for mapping one of the body's most elegant systems: DNA mismatch repair.…