PCR inventor Kary Mullis dies aged 74

Kary Mullis, the American biochemist who won the 1993 chemistry Nobel prize for inventing the polymerase chain reaction (PCR), has died. PCR uses an enzyme – a heat stable DNA polymerase – and cycling temperatures to amplify DNA, creating thousands or millions of copies of a chosen sequence, which can then be used for analysis or experimentation. It has become an indispensable technique in molecular biology.