James Watson: DNA Discovery and Scientific Legacy

Introduction

The discovery of DNA was one of the most important discoveries in the history of humanity, and it was accomplished by James Watson and Francis Crick. Their discovery of the structure of DNA allowed scientists to begin to understand the mechanism behind inheritance. While many scientists over the years had studied heredity, beginning with Gregor Mendel, no one had been able to discover the exact mechanism by which heredity actually works. It was not until technology advanced to the point where scientists could determine the structure of molecules that the structure of genetic material could finally be identified. After much research and some failures, two scientists working together ultimately determined the molecular structure of the genetic molecule, allowing the study of its exact mechanism to begin.

James Watson was one of the scientists responsible for this discovery, and since that time he has become one of the greatest scientists in American history. However, Watson was also a human being capable of human error, which at the end of his long and illustrious career all but ruined him.

Early Life and Education

James Dewey Watson was born in Chicago, Illinois, on April 6, 1928, the only son of James and Jean Watson. His father was a businessman while his mother worked for the university. His entire early life was spent in Chicago, where he attended Horace Mann Grammar School and South Shore High School ("Biography James Watson"). After just two years of high school, in 1943, Watson was admitted to an experimental program that allowed gifted high school students to enter the university early. Through this program, he graduated college in just three years with a B.S. degree in Zoology.

An avid birdwatcher since boyhood, Watson then entered Indiana University and received a Doctorate in Zoology in 1950. It was at Indiana University, however, that Watson became interested in genetics. After graduating, he took a position at the Merck National Research Council in Copenhagen. During this time, Watson attended a symposium where he was introduced to the new X-ray diffraction technology, which could be used to reveal the structures of molecules. This exposure influenced him greatly, and he shifted the focus of his research toward discovering the structure of the genetic molecule using this new technology (Wright 1999).

Watson then went to work for the Cavendish Laboratory at Cambridge University in England, where he teamed up with another young scientist named Francis Crick. It was during this partnership that the two engaged in one of the greatest scientific discoveries the world has ever known. Together they applied the latest X-ray diffraction technology to determine the molecular structure of the genetic molecule. After two years of research, on February 28, 1953, Watson and Crick discovered that the structure of the genetic molecule — deoxyribonucleic acid (DNA) — was a double helix ("James D. Watson, Ph.D."). In other words, it resembled a ladder twisting around a cylinder. As Watson later described it: "These pairs of bases could thus serve as the rungs on the twisting ladder of DNA" (Wright 1999). Watson and Crick's paper on the subject was published the following April in the journal Nature. Both men became instant celebrities and went on to hold prestigious positions in academia.

The Discovery of the DNA Double Helix

Watson and Crick's discovery was the culmination of decades of research into the mechanism behind inheritance. It was the monk Gregor Mendel who first began to scientifically study the phenomenon of inheritance. By observing successive generations of plants, Mendel worked out the basic mathematical formula of inheritance. While his research established that there was a mathematical basis for heredity, the underlying mechanism remained unknown.

A scientist named Walter Sutton later determined that the mechanism of inheritance was connected to chromosomes found in the nucleus of the cell. Around the same time, Johann Miescher was researching the basic structure of chromosomes and determined that they were composed of acids. By 1900, he had worked out a simple basic structure for the genetic molecule, concluding that it must consist of three parts: a phosphate, a sugar, and a base, and that there were four possible bases (Wolf 2003).

Scientific Predecessors and the Road to Discovery

It was a different scientist, Edwin Chargaff, who later discovered that the four bases — adenine, thymine, cytosine, and guanine — were divided into two pairs, A-T and G-C, which appeared in equal amounts. In other words, the amount of adenine found in a sample equaled the amount of thymine, and similarly for cytosine and guanine ("James Watson, et al."). Chargaff had thus established that the molecule must consist of four bases, with each base paired to a specific partner.

The real breakthrough came when technology allowed scientists to visualize molecular structures through X-ray diffraction. Watson's introduction to this technique prompted his shift from studying birds to studying the structure of the genetic molecule. He met Francis Crick at Cambridge University, and the two spent the next two years theorizing and experimenting until Watson assembled all the available evidence into a coherent structural model of DNA.