DNA discovery as hereditary material and molecular structure

¶ … Discovery of DNA

On the afternoon of February 28, 1953, British physicist Francis Crick announced in a pub in Cambridge, England, that he and James Watson, an American geneticists, had discovered "the secret of life" on planet Earth, meaning that Crick and Watson had "figured out the structure of DNA" (deoxyribonucleic acid) and that this strange material, known as a double helix, had the capacity to "unzip to make copies of itself," thus confirming many suspicions by other scientists that DNA was the foundation of life's hereditary information (2009, "James Watson & Francis Crick," Internet).

However, Crick and Watson did not discover DNA itself because in 1868, Swiss biologist Friedrich Miescher "carried out the first carefully thought-out chemical studies on the nuclei" of human cells and after obtaining a substance based on phosphorus which he dubbed "nuclein." Miescher also discovered that this substance was acidic and that it contained histones, "a class of proteins responsible for the packaging of DNA" which remained somewhat mysterious until the late 1940's (2009, "The Search for DNA," Internet).

In 1943, some ten years before Watson and Crick unraveled the mysteries of DNA, many biologist and geneticists were convinced that DNA played some type of major role in human inheritance while other argued that such a thing was not possible. Yet the first solid evidence that DNA was the carrier of human genetic information came about at the Rockefeller Institute via research conducted by Oswald Avery, Colin MacLeod and Maclyn McCarthy. These three men came to the conclusion that DNA "carried the genetic message" and that virulent strains of a particular bacterium known as streptococcus pneumonae did indeed contain DNA. Not

surprisingly, many scientists still were not convinced of the genetic properties of DNA (2009, "The Search for DNA," Internet).

In 1952, researchers Alfred Hershey and Martha Chase, via the utilization of radioactive isotope tracer experiments, came to the conclusion that a bacterial virus called bacteriophage T2 did contain DNA, for when "a bacterial virus infected its host cell (escherichia coli)," it was found that DNA of the T2 virus "and not the protein coat which enters the host cell" provides the genetic data for the replication of the virus (2009, "The Search for DNA," Internet), thus proving that earlier experiments were accurate and that DNA was the carrier of human genetic information.