Kary Mullis: Complete Life and Legacy of the Inventor of PCR

Kary Banks Mullis (1944–2019) was an American biochemist who invented the polymerase chain reaction (PCR), a technique that allows a tiny amount of DNA to be copied billions of times in a test tube. He received the 1993 Nobel Prize in Chemistry, sharing it with Michael Smith. A talented but unconventional personality, he was known for his independent thinking, and he also held some views, particularly on HIV/AIDS, that most scientists rejected. His legacy is secure: PCR is one of the most widely used techniques in biology and medicine.

Early Life and Family

Kary Mullis was born on 28 December 1944 in Lenoir, North Carolina, in the Blue Ridge foothills of the southeastern United States. He grew up in a small town and in a rural environment, and spent part of his childhood in Columbia, South Carolina. As a boy he was curious about the natural world and built experiments, including a homemade rocket project that he later described with humour. He credited his early freedom to explore and tinker for his later creativity.

Education and Mentors

Mullis studied chemistry at the Georgia Institute of Technology (Georgia Tech), graduating with a bachelor's degree in 1966. He then went to the University of California, Berkeley, for graduate study in biochemistry and received his PhD in 1972. After the PhD, he did postdoctoral work in cardiology and pharmaceutical chemistry. He later moved to the biotechnology company Cetus Corporation in Emeryville, California, in 1979, where he synthesised oligonucleotides, short pieces of DNA.

Career Timeline

Major Scientific Contributions

Mullis's invention of PCR is his major contribution. The idea is to use two primers that flank a target DNA sequence and a DNA polymerase to copy the sequence over and over: heat to separate the strands (about 94 °C), cool to let primers bind, then extend at about 72 °C. Each cycle doubles the amount of target, so n cycles produce about 2ⁿ copies. The method became practical and automated when the heat-stable polymerase from Thermus aquaticus (Taq) was used, so enzyme did not need to be added after every heating step.

Other points about his work:

• Mullis worked on the early development of PCR with colleagues at Cetus, who helped bring the technique to publication and to wide use.
• He had other inventions and patents in his career, including work on a UV-sensitive material.
• After leaving Cetus in 1986, he worked as a consultant and in different companies, and became well known as a speaker.

Awards, Honours and Nobel Prize

The 1993 Nobel Prize in Chemistry was divided equally between Kary B. Mullis "for his invention of the polymerase chain reaction (PCR) method" and Michael Smith "for his fundamental contributions to the establishment of oligonucleotide-based, site-directed mutagenesis and its development for protein studies." Mullis also received the Japan Prize in 1993 and other awards. The prize was in Chemistry, not Medicine, although PCR is widely used in medicine.

Personality, Struggles and Lesser-Known Facts

• The highway idea: Mullis said that he thought of PCR while driving in the mountains of northern California in April 1983. Whether or not every detail is exact, he often told this story.
• Independent mind: He enjoyed challenging conventional views. In his writings and talks he questioned the scientific consensus on some topics, including the link between HIV and AIDS, which is firmly established. Students should know that these opinions were rejected by the scientific community, and that scientific ability in one area does not guarantee correct views in another.
• Surfing and travel: He loved surfing and the California lifestyle, and wrote a memoir, Dancing Naked in the Mind Field.
• Recognition vs. reward: Cetus sold the PCR patent rights to a pharmaceutical company for a large amount, while Mullis received a modest bonus; he spoke about this contrast.
• Technique larger than the inventor: PCR was developed by many people, including those who made Taq practical, and the Nobel Prize recognised the invention of the method.

Legacy and Influence on Modern Chemistry

PCR changed biology and medicine. Within a few years of its invention, it was used in genetic diagnosis, forensic identification and genome research. The Human Genome Project used PCR-based methods heavily. In the COVID-19 pandemic, RT-PCR became the standard test for SARS-CoV-2 in India and across the world. Real-time PCR allows quantitative measurement of gene expression and viral load. Indian diagnostic laboratories and research institutes use PCR for tuberculosis, dengue, hepatitis and many other diseases. PCR also enables DNA fingerprinting, which is accepted in Indian courts as scientific evidence.

Lessons for Students

1. A simple idea can be powerful. PCR is built from steps every chemistry student knows: heating, cooling, and enzyme-catalysed bond formation.
2. Be curious outside your assignment. Mullis was working on oligonucleotide synthesis when the idea arose.
3. Technique needs teamwork. The idea needed Taq polymerase, machines and optimisation by many people.
4. Stay evidence-based. Brilliance in one area does not make every opinion correct; test claims against data.

FAQ

When did Mullis think of PCR?

In April 1983, while working at Cetus Corporation in California.

Which enzyme made PCR practical?

Taq polymerase from the heat-loving bacterium Thermus aquaticus.

Did Mullis win alone?

No. He shared the 1993 Nobel Prize in Chemistry with Michael Smith, who was honoured for site-directed mutagenesis.

Why do students study PCR?

PCR connects nucleic acid chemistry, enzyme catalysis and thermodynamics, and appears in biochemistry and biotechnology sections of competitive exams.

Published by ABC Chemistry — IIT-JAM | CSIR-NET | GATE Chemistry Coaching. Visit abcchemistry.com