A new way to control a powerful but finicky process called the polymerase chain reaction raises the possibility of a “DNA photocopier” small enough to hold in your hand. Such a device could identify the bacteria or virus causing an infection even before the symptoms appear.
Kary Mullis developed PCR in 1983 and received the Nobel Prize for his invention. A key advance in the field of molecular biology, it can make billions of identical copies of small segments of DNA for use in molecular and genetic analyses.
