The name Kary Mullis is associated with:

Question

Accepted Answer

The correct option is 3: Polymerase chain reaction

Kary Mullis is unequivocally credited with the invention of the Polymerase Chain Reaction (PCR) technique in 1983, a breakthrough that fundamentally changed molecular biology and genetic science. PCR is an elegant, yet powerful, *in vitro* method used to rapidly create millions to billions of copies of a specific DNA segment, allowing scientists to analyze minuscule samples of genetic material. Mullis conceived of the core idea: using short synthetic DNA primers and a heat-stable DNA polymerase (such as *Taq* polymerase) to cycle through three temperature-dependent steps—denaturation, annealing, and extension. This cycling achieves exponential amplification of the target DNA, essentially acting as a molecular photocopier. This invention was so monumental that it revolutionized fields ranging from disease diagnostics and gene cloning to forensics, ultimately earning him the Nobel Prize in Chemistry in 1993.

The incorrect option is 1: Gel electrophoresis

Gel electrophoresis is a foundational laboratory technique used to separate macromolecules, such as DNA fragments, RNA, and proteins, based on their size and electrical charge. This process involves applying an electrical field to push the molecules through a porous matrix, such as an agarose or polyacrylamide gel. The technique itself predates Kary Mullis’s work by several decades, with its origins tracing back to the 1930s work of Arne Tiselius on protein separation. While gel electrophoresis is an essential tool in molecular biology, often used to visualize the products of a PCR reaction, it is not the innovation associated with Mullis.

The incorrect option is 2: DNA sequencing

DNA sequencing is the biochemical process of determining the precise order of nucleotides (A, T, C, and G) in a DNA molecule. The most historically important and widely adopted method, known as the Sanger sequencing method (or chain-termination method), was primarily developed by Frederick Sanger and his colleagues in the mid-1970s. Mullis's invention, PCR, is often a necessary upstream step for sequencing, as it generates the required large quantity of template DNA from a small initial sample. However, Mullis's innovation was the amplification itself, not the core method or chemistry used for reading the nucleotide sequence.

The incorrect option is 4: DNA fingerprinting

DNA fingerprinting, also known as DNA profiling, is a forensic and diagnostic technique developed for individual identification and paternity testing by analyzing unique, highly variable patterns in a person's DNA. The invention of this specific application is credited to Sir Alec Jeffreys in the United Kingdom in 1984, shortly after Mullis invented PCR. Although PCR has since been incorporated into DNA fingerprinting methods to amplify the minuscule amounts of DNA found at crime scenes, Kary Mullis’s name is directly linked to the universal amplification *technique*, not the development of the specialized forensic method.