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DNA Structure, Replication, and Technology

DNA Structure, Replication, and Technology

History and DNA Structure, Replication, and Technology

Standing on the Shoulders of Unknown Giants

It could be argued that the field of biology became the field of DNA research around the time of James Watson and Francis Crick's discovery of the structure of DNA. Since then, much of biology research has focused on learning more about manipulating DNA and the functions of DNA, from protein coding to evolutionary processes. While they, along with Maurice Wilkins, earned the Nobel Prize in 1962, another researcher, Rosalind Franklin, was not awarded the Nobel. Despite the essential nature of her work in the discovery of the crystal structure of DNA, she died 4 years before the award was given, and the Nobel Prize is not given posthumously.

Nevertheless, the crystal structure of DNA stands on the shoulders of many others who laid the foundation for the discovery that DNA is the fundamental molecule of life. While many know of Darwin and Mendel, few know of Hugo de Vries, Carl Correns, and Erick von Tschermak-Seysenegg. Their works together provided the link between Mendel's inheritance and Darwin's evolution, creating a gene model for natural selection. All these giants standing on giants must be obnoxious for the average person trying to watch the show behind them.

While we know that DNA is the molecule of life, how did we first find DNA? Friedrich Mieschler was the first to crudely isolate DNA from pus, calling it nuclein. Emil Fischer and Albrecht Kossel were the first to chemically isolate the nucleotide bases in the late 1800s, including isolating guanine from sea bird poop. Finally, Phoebus Levene was the first to show that a DNA monomer is composed of a base, sugar, and phosphate group. All that scientific work in poop and pus, and yet few ever remember their names.

Though Thomas Hunt Morgan showed that hereditary information is found on the chromosome in the early 20th century, he was not the first to report it. Theodor Boveri showed that each chromosome houses different genetic information, and he also showed that each part of the chromosome is responsible for inheriting a certain gene. Thomas Hunt Morgan's work was the culmination of Boveri and Walter Sutton's work supporting the chromosome theory of inheritance.

Even after Watson, Crick, Franklin, and Wilkins' publications about the structure of DNA, work was required to show the mechanism of DNA replication. An experiment from Matthew Meselson and Franklin Stahl showed that DNA replication is semi-conservative, meaning that each daughter strand of DNA contains one parental strand from the double helix. And, while Crick followed on his double helix work to show codons coded for amino acids, it was the work of Marshall Nirenberg, Robert Holley, and Hargobind Khorana that actually unlocked the genetic code.

Therefore, while biology textbooks make it sound like there were only 5 or 6 people who contributed to the discovery of DNA, inheritance, and chromosomes, you now know that there were many. Every major advance in DNA research has come on the shoulders of unknown or forgotten scientists. The work is not finished yet, and many questions remain over the role of epigenetics in evolution. Are DNA and histone modifications inherited from one generation to the next? How is this inheritance regulated? A recent study in rats showed that what can be learned in one generation can affect future generations, but how does this work, and is this applicable to humans? Biology is all about unanswered questions, and while we already know so much about DNA, we still understand little. Nevertheless, if you play your cards right, you too could be a footnote in history, if not a Nobel Prize winner.

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