He developed the Polymerase Chain Reaction (PCR) in 1983 and won the Nobel Prize in 1993 ("Polymerase Chain Reaction"). The Polymerase Chain Reaction is a central technique in biochemistry and molecular biology that gives people the opportunity to amplify specific DNA sequences. In 1986, Mullis began using Thermophilus aquaticus (Taq) DNA polymerase to amplify specific sequences of DNA and because it was resistant to heat it only needed to be added once rather than multiple times as in the old technique. Taq made the technique of DNA polymerase more feasible and less tedious ("Polymerase Chain Reaction").
Mullis also invented what is known as a UV-sensitive plastic that changes color when reflected on by light ("Kerry Mullis' biography"). Currently, Mullis is working on what he calls Alternate LLC, an approach in which the immune system can neutralize invading pathogens and toxins ("Kerry Mullis' biography").
How does this affect me?
Amplifying specific DNA sequences through PCR saves scientists money and time because they donít have to repeatedly add DNA polymerase in order to magnify a specific DNA sequence. This helps the economy today and provides the scientific community with a the heat resistant DNA polymerase they may need for further studies. This is also beneficial for people who are affected by a certain DNA sequence and want quick results with specific details about the sequence. This will most likely benefit me in the future.
(image from http://oregonstate.edu/dept/ncs/photos/mullis.jpg)